What are the problems with biofuels

[sweeteviljesus]

If we could replace 100% of transportation fuels with renewable, carbon-neutral sources, what are some of the new problems that this would create? The obvious one would be if the source was also a food source, but suppose that it wasn't. If the fuel were significantly cheaper than oil, I can see it causing economic chaos in the Middle East.

Thanks for your help,
Rob

[Hypno-Toad]

The big argument against bio-fuels is that they use more energy to produce than they provide. I don't know if this is accurate since the results of experiments are so politicized. But even if that's true now, bio-fuels should still be pursued. All new technologies suck when they're still being introduced. It's idiocy to refuse to consider any kind of innovation because it isn't an immediate panacea.

And I know that Brazil is a huge consumer of ethanol from sugar-cane. So at least one nation has committed to the technology.

[Balthisar]

How do you make CO2 emissions carbon neutral?

[Hypno-Toad]

The neutral term comes from the fact that the source of the fuel is a plant which takes carbon out of the air to build itself. Petroleum and coal take carbon out of the ground where it was sequestered out of the system and then add it to the air.

[Mangetout]

The big argument against bio-fuels is that they use more energy to produce than they provide.They don't have to do that though - I think you went on to cover this, although not in explicit wording, in the rest of your post.

One of the other problems with biofuels is scalability - fossil fuels are good sources of energy because they are the results of millions of years worth of stored-up sunlight - obviously with biofuels, we can only harvest the energy from sunlight (via plants) as it falls.

[sweeteviljesus]

In a thread about a year ago about cellulosic ethanol, one of the posters said that if you were able to extract ethanol from, say, switchgrass and use corn stover, municipal waste streams and other agricultural waste, you would still come up short. He claimed that only algae could scale up enough.

Mine intent with the question was to assume that we could do it. If so, what would the problems be?

Thanks,
Rob

[Balthisar]

The neutral term comes from the fact that the source of the fuel is a plant which takes carbon out of the air to build itself. Petroleum and coal take carbon out of the ground where it was sequestered out of the system and then add it to the air.
I know that's what the term means, but in terms of renewable energy -- crops -- then it's not possible to be carbon neutral. You'll always put more CO2 into the air than you take out of it. Aside from crops, there's no such thing as renewable energy, e.g., hydrogen's not a renewable source, because you're using electricity to make it. Of course you have to draw a line somewhere lest we just call crops a converted form of solar energy.

[Balthisar]

[My] intent with the question was to assume that we could do it. If so, what would the problems be?
You'd still have Kyoto-minded people worrying that instead of feeding the world's poor, the United States is using all of the arable land to fuel its vehicles. Venezuela would overthrow Hugo Chavez since the demand for oil would no longer pay for his socialist agenda. I imagine the energy companies (BP, Shell) would mostly be okay since they'd've already integrated themselves into the new status quo. It might spur the the desalination industry since all of these crops would need fresh water. The jimadores would be out of work as all of the Mexican agave famers burn their crops in favor of corn production, and the price of tequila would skyrocket again like back in 2001.

Overall, I can't imagine any real insurmountable problems other than the original premise (no offense intended at all, because if I'm wrong I always take value in being corrected).

[sweeteviljesus]

I know that's what the term means, but in terms of renewable energy -- crops -- then it's not possible to be carbon neutral. You'll always put more CO2 into the air than you take out of it. Aside from crops, there's no such thing as renewable energy, e.g., hydrogen's not a renewable source, because you're using electricity to make it. Of course you have to draw a line somewhere lest we just call crops a converted form of solar energy.

This is tangential, but how do you figure that you will be creating more CO2 than you take in?

Rob

[Ludovic]

This is tangential, but how do you figure that you will be creating more CO2 than you take in?

RobIt's assuming the harvesting process is run on non-carbon neutral equipment. Since you'll eventually be releasing everything you produce AND the carbon from your equipment it's not really carbon neutral.

You could solve this by making the creation and collection process carbon-neutral. (Either through using more carbon-neutral equipment or less equipment in general.)

[Hypno-Toad]

You could solve this by making the creation and collection process carbon-neutral. (Either through using more carbon-neutral equipment or less equipment in general.)

If you're producing bio-fuels, it seems natural to use it in your equipment. Personally, I favor a multiple source approach. Biofuels augemented with wind and solar power. A harvester with hybrid engines and additional batteries charged from wind or solar stations would help reduce the carbon emmissions of production. This could really help make bio-fuels carbon neutral.

I hope I'm not fantasizing.

[Martin Hyde]

So what's the straight dope on biofuels?

I haven't followed the science nearly as much as I should have. On one hand, I've seen tons of reports saying that switchgrass, corn based fuels operate at a "deficit." That they require more energy to produce than they create.

I've seen contradictory reports to that.

For example the other day on the history channel I was sort of listening to a documentary they were running on biofuels as "background" noise while doing some paper work and I repeatedly heard the people on the documentary say that biofuels are efficient and that they do produce more energy than they use.

Is there a legitimate answer, and is the discrepancy between the differing explanations one of ill-defined terminology or methodology or are there genuinely people out there spreading misinformation to advance an agenda? I can imagine interested parties on both sides who would distort the data one way or another (farmers for example and their lobbying groups would probably distort the data in favor of it being efficient while producers of fossil fuels would probably be doing the opposite.)

[Hypno-Toad]

One approach to improve the system is genetically altering the plants so that every part of the plant is usable. This really helps but I have not heard if it has been successful or not.

Martin, you seem to have hit the nail on the head on the confusing nature of the issue. The straight dope on bio-fuels seems to depend on who you want to believe. And yes, it is highly debated topic that gets spun very heavily.

[lowbrass]

So what's the straight dope on biofuels?

I haven't followed the science nearly as much as I should have. On one hand, I've seen tons of reports saying that switchgrass, corn based fuels operate at a "deficit." That they require more energy to produce than they create.

I've seen contradictory reports to that.

For example the other day on the history channel I was sort of listening to a documentary they were running on biofuels as "background" noise while doing some paper work and I repeatedly heard the people on the documentary say that biofuels are efficient and that they do produce more energy than they use.

Is there a legitimate answer, and is the discrepancy between the differing explanations one of ill-defined terminology or methodology or are there genuinely people out there spreading misinformation to advance an agenda? I can imagine interested parties on both sides who would distort the data one way or another (farmers for example and their lobbying groups would probably distort the data in favor of it being efficient while producers of fossil fuels would probably be doing the opposite.)

I think it's pretty close, and you come out with negative/positive net energy depending what assumptions you make for your data. I recall a long thread about this last year, and I came away with the impression that those who claim it's negative efficient are relying on the work of one person and that the data he used is horribly out of date. Pimental was the name IIRC. Also, he made a lot of assumptions such as the energy cost of building ethanol plants, transporting the materials, etc., which I think would be mitigated over time once the infrastructure is in place.

[Enola Straight]

One of the biggest advantages of biofuels is the variety of feed stok the fuels cam be made from.

Ethanol dosen't need to be derived solely from corn...it can be fermented from any carbohydrate; cereal grain which has for some reason or other been deemed unfit for human consumption or animal feed, out-of-season candy, stale bread, waste from restaurants and other food prepatory businesses.

The same is said of Bio-diesel; can be brewed from a variety of lipidous (fatty) sources, such as vegetable oil from plants, and lard from animals. Can be sourced from dedicated crops, or from waste sources, such as used deep fryer grease.

[Chronos]

One key point here is that there are different kinds of biofuels, and they're not all equally efficient. Ethanol gets a lot of press, since vehicles designed to burn gasoline can also burn ethanol or gasoline-ethanol mixtures, but ethanol is currently in the red. Biodiesel, on the other hand, is used in diesel engines, and (depending on who you ask) is probably in the black. And then there's diesel produced from various waste sources (from used fry-oil to sewage), which is certainly efficient (since you'd have that waste anyway, and have to do something with it), but which doesn't scale up well (IIRC, if all fry oil in the US were converted to fuel, it'd only meet less than a percent of the country's needs).

[Enola Straight]

Biodiesel, on the other hand, is used in diesel engines, and (depending on who you ask) is probably in the black. ).

Indeed, last time I checked, biodiesel contains 3.24 times the energy invested in it's manufacture.

[LSLGuy]

I'd like to get back to the OP.

Pretend we (ie the First World, not just the USA) now have a way to grow & process bio-whatever at sufficient scale & efficiency such that we are burning zero petroleum for all transportation uses, and also for all production energy needs of bio-whatever. Ballpark the entire process is therefore carbon-neutral over a couple-year time frame.

Coal & natural gas are still used in electrical plants just as now.

What else changes in the world? My WAGs:

Russia (?), Iran, Kuwait, Saudi Arabia, Venezuela, etc., have only 5-10% of their current oil-fueled income. Economic & social chaos ensue.

Other oil-producing, but not oil-exclusive countries (Russia, Norway, Britain, Mexico, US (?)) have some upheavals on both the supply as well as demand side.

US, Japan, EU reduce their cost of imported energy to 5-10% of what it was. Major shifts in current account balances, trade deficits, etc. Major shifts in currencies.

China's coal use for electricity becomes the lion's share of all net carbon emmisions planetwide.

Large oil tanker fleets become uneccessary. Meanwhile, a new trade springs up between First World countries in either the feedstocks or the finished product. Come to think of it, we may still need those tankers; I doubt the Swedes can grow bio-whatever as cheaply as the southern US can.

etc.

[Baffle]

That's right. Ruin the earth so you don't worry about possibly hurting someone's economy.

[kunilou]

I have a bias here. I'm a corn guy. Not an ethanol guy, but ethanol certainly touches on a lot of what I do.

The big problem will be scalability. It doesn't matter whether you use corn, sugarcane, switchgrass, hemp or algae. You'll need to grow a lot of it to turn it into fuel. Same with biodiesel -- there aren't that many restaurant grease traps around to fuel all the trucks.

Since you need to grow a lot, you'll need a lot of land -- some of that land might better be used to grow food crops, some for non-food crops (like cotton) and some might be environmentally fragile and thus better left alone.

Consider Brazil. It's been on a crash course to produce ethanol for more than 30 years. Today ethanol accounts for 20 percent (http://yaleglobal.yale.edu/display.article?id=6817) of Brazil's fuel needs.

That's it. 20 percent.

No serious advocates of biofuels claim they'll completely replace petroleum fuels. That said, they can make a difference on the margins. When Katrina closed down the Gulf Coast refineries in 2005, it effectively cut off about 11 percent of the total U.S. oil supply. The price of gasoline went up 40 cents per gallon overnight.

If biofuels can replace (or more likely augment) 20 percent of the need for oil, it will be a good thing. But it won't be a radical transformation.

Lowbrass is right about studies where the assumptions shape the data. For instance, if I harvest 150 bushels of corn, and I sell 100 for livestock feed and 50 for ethanol, how does the study assign the costs? Does it assign 1/3 of the cost of the tractor and combine, the fuel to run them, the fertilizer applied to the field, the money I pay to my accountant to do my taxes, etc. to ethanol? Does the study assume there would be no ethanol without the tractor, fuel, fertilizer, accountant, etc. and assign 100% of their costs to the ethanol? Or does it assume that I plant and harvest a crop anyway, and only assign the cost of the seed used to grow the extra corn that I sold for ethanol?

[Chronos]

Indeed, last time I checked, biodiesel contains 3.24 times the energy invested in it's manufacture.OK, I'll take your word for it. I couldn't remember the numbers, and wanted to make sure I had enough weasel words in there in case I was wrong.

[Diceman]

If biofuels can replace (or more likely augment) 20 percent of the need for oil, it will be a good thing. But it won't be a radical transformation.
Don't discount the value of augmentation. A "flex-fuel vehicle" can use either gasoline or ethanol. If another Katrina hits, the ethanol plants should still be up and running, since they'll most likely be scattered throughout the Midwest, West, and South. Conversely, if a major crop failure crimps the ethanol supply, we still have gasoline.

[Intravenus De Milo]

Some of the most compelling arguments I've heard for favoring biodiesel over ethanol is that biodiesel, by design, can run in the same engines and be transported using the same infrastructure that is already in place to handle regular diesel fuel. Ethanol, IIRC, cannot be piped cross-country the way that diesel and petrol can, and thus one's access to ethanol would be partly determined by their proximity to an ethanol plant.

Additionally, biodiesel is apparently becoming a "cottage industry" phenomenon, at least near where I live. Some people are literally producing biodiesel in the backs of their houses, and local restaurants are more than happy to donate used grease. So you get the double-bonus of using an environmentally-friendly fuel AND supporting local business, which many people in my area are very keen on. And from what I've read, an increasing number of diesel-fuel vehicles are expected on the American market in the near future, so we'll see how many people embrace another form of alternative fuel.

[Freezair SilverEye]

One big question of mine on the issue of biofuels is: Which industry produces more natural "waste," agriculture or animal products? It seems to me like an early step toward more widespread biofuel use would be determining how much would be naturally available for biofuel production before allocating large portions of crops/animals for biofuel. And of the two, in which does the waste account for a larger portion of the products? Of course, industry-level biofuel production could not be based on waste products alone, but it'd be interesting to know simply from a springboard perspective.

[Askance]

Using otherwise wasted crop byproducts to produce biofuels can be a splendid and worthwhile thing, assuming gathering and processing it does not use more fuel than it produces. Planting more crops to produce it is worse than useless, it's actively harmful. Not to mention that most arable land is already in use for food; what food are we going to forego to produce ethanol instead? Brazil are only achieving it by chopping down the Amazon rainforests.

The problem is that Western governments are beholden to rural lobbies (or act as if they are) and so this looks like a win-win for the farmers and their political supporters. The idealisation of farming life by our almost entirely urbanised communities seems to insulate them from rational considerations. We have a similar situation with nuclear power, "clean coal", and many other hobby horses, like any other bandwagon people jump on board with the slightest excuse.

The only scalable carbon-neutral forms of energy production are solar and geo-thermal. Smaller but significant contributions can come from hydro, wind and tidal. None of those are going to provide enough energy just yet to power our economies as they are, yet we need to start cutting our carbon emissions now - this year. Reducing energy usage and funding research into large, cheap solar, and geo-thermal where available, is all we can do right now. That's it, folks, concentrating on anything else is a distraction from the main game.

[Balthisar]

Reducing energy usage and funding research into large, cheap solar, and geo-thermal where available, is all we can do right now. That's it, folks, concentrating on anything else is a distraction from the main game.
What's your beef with nuclear? In terms of energy efficiency, conversion, distribution infrastructure, costs, and environmental impact nothing beats electricity. We need to overcome some storage problems for mobile applications, but it's being worked on. When it comes to production density, nothing beats nuclear.

[Hypno-Toad]

Everybody talks about creating energy, but to me Bio-fuels from waste are worthwhile simply because it removes all that waste from the landfills. Even if it isn't totally energy efficient, it at least processes the material and gets back a little something to mitigate the cost.

[Stranger On A Train]

What's your beef with nuclear? In terms of energy efficiency, conversion, distribution infrastructure, costs, and environmental impact nothing beats electricity. We need to overcome some storage problems for mobile applications, but it's being worked on. When it comes to production density, nothing beats nuclear.Nuclear fission also has some serious problems with waste disposal, fuel processing/reprocessing, and operational safety issues. I don't think we'll be able to get away from it in the near term--conventional and forseeable renewable sources may be renewable, but they aren't sufficiently scalable to completely supplant nonrenewable (fossil fuel and nuclear) power sources--but even fission should be considered a stopgap to developing less polluting and more ultimately sustainable energy sources.

Stranger

[Public Animal No. 9]

If we could replace 100% of transportation fuels with renewable, carbon-neutral sources, what are some of the new problems that this would create? The obvious one would be if the source was also a food source, but suppose that it wasn't. If the fuel were significantly cheaper than oil, I can see it causing economic chaos in the Middle East.

Thanks for your help,
Rob
Abstract from a paper in the Proceedings of the National Academy of Science (Hill et al. 2006):
Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels.
My view is that biofuels are excellent in certain situations, but not a viable long-term solution to sustainable transportation fuels. Biodiesel is more promising than ethanol, and the only way ethanol will really work is to find a cost-effective way to generate it from cellulose rather than from corn. Brazil's ethanol strategy works as well as it does because they produce it from sugar cane, rather than from corn or other grains, with a significant improvement in ethanol yield.

There are numerous other problems with biofuels that need to be addressed - increased fertilizer and pesticide runoff, decreased land in conservation programs (leading to likely decreases in agricultural productivity and loss of topsoil), widely distributed feedstock sources (in terms of energy content per area as opposed to the relatively high energy content per area for fossil fuels), and significant variability in feedstock production potential (severe energy impacts during drought years, for instance).

These are the technical issues, and don't address problems like we're now seeing with significant increases in prices for corn and corn-based foods (including meat).

Biofuels have a lot of promise, and do have the potential for reducing petroleum consumption. IMO, though, the first thing we should be looking at is significantly increasing our efficiency. The technologies and approaches are much more well developed, but people still want to drive the big dogs, and will as long as gasoline prices don't increase significantly.

[kunilou]

The only scalable carbon-neutral forms of energy production are solar and geo-thermal. Smaller but significant contributions can come from hydro, wind and tidal. None of those are going to provide enough energy just yet to power our economies as they are, yet we need to start cutting our carbon emissions now - this year. Reducing energy usage and funding research into large, cheap solar, and geo-thermal where available, is all we can do right now. That's it, folks, concentrating on anything else is a distraction from the main game.

The flaw in this argument is that it requires throwing out the internal combustion engine and the entire kajillions of dollars of infrasturcture that has grown up around fossill fuels over the last 125+ years. What's the environmental cost of junking every car, truck, bus, airplane, ship, oil refinery, natural gas pipeline and filling station in the entire world and replacing them with solar and geothermal-powered electric vehicles?

Biofuels are a viable replacement/supplement for fossill fuels precisely because they fit into the current system with only minor modifications.

Which approach is better -- small but meaningful improvements to the current technology that have immediate impact, or letting the current technology plod along while we try to come up with giant, revolutionary breakthroughs?

That's it, folks, concentrating on anything else is a distraction from the main game.

[Askance]

What's your beef with nuclear? In terms of energy efficiency, conversion, distribution infrastructure, costs, and environmental impact nothing beats electricity. We need to overcome some storage problems for mobile applications, but it's being worked on. When it comes to production density, nothing beats nuclear.Face it, even if it was technically the best option it's just not going to happen, too many people are too scared of it (not matter what your opinion on how valid that fear is). No community is ever going to put up with a new nuke near them ever again, let alone welcome one.

But factually:

i) there isn't that much available uranium. If all electricity in the world today was produced by nukes we'd have maybe 10-15 years' worth of economically recoverable uranium (mostly in Australia, Canada and Russia) then we have to start looking for another power source; we may as well skip that step and do that now.

ii) the last good hope for permanent storage of high-level waste, Synroc (http://en.wikipedia.org/wiki/Synroc) or its equivalents, has recently been shown to degrade hugely faster than theory said and so we are left with no economic way of dealing with it.

iii) a whole-cycle evaluation of carbon emissions for nukes will surely show it emits less than a coal plant, but still sizeable and I believe comparable to a natural gas powered plant. The amount generated in the building, operation, transport, and waste disposal (however you plan that) is surprisingly large; with gas all you need is a well and a pipeline, with nukes you need a huge and secure transport infrastructure.

iv) a nuke plant takes a minimum of 10 years to build, average more like 15. The number we would need to build to make a difference starting right now would be prohibitive, and would not start to reduce carbon emissions until they came online in over a decade - when it will substantially too late to help (and don't forget all the emissions of construction - pretty much all fossil fuel powered - have just contributed to making the problem worse before they come on line).

v) it's not as cheap as you think. Not a single nuke plant has been built anywhere in the world without substantial government subsidy, mostly in the form of free disaster insurance but also significant tax breaks especially during the long construction phase. Factor that cost in and suddenly electricity from nukes shoots up to be enormously expensive.

vi) I hardly need detail the security risks of having all that concentrated uranium shipped around the world, the expense of guarding it, and the proliferation that can result (as it is right now in Iran).

[slaphead]

Face it, even if it was technically the best option it's just not going to happen, too many people are too scared of it (not matter what your opinion on how valid that fear is). No community is ever going to put up with a new nuke near them ever again, let alone welcome one.

Really? France have been getting something like 80% of their electricity from nuclear for years. Apparently their most serious ever nuclear mishap was three doofuses walking into a particle accelerator without putting their moon suits on and getting fried. I can't imagine they have the same level of fear as e.g. the US.

[ralph124c]

Turpenes 9distlled from pine tree wood0 resmebel gasoline. The japanese used turpene-based fuels as a substitute for aviation gasoline, during WWII. Could we produce adequate motor vehicle fuel, from fast-growing pine trees?
Also, (during WWII), there was serious interest in producing fuels from the (desrt0 guayule plant-is this feasible?

[sweeteviljesus]

Abstract from a paper in the Proceedings of the National Academy of Science (Hill et al. 2006):

My view is that biofuels are excellent in certain situations, but not a viable long-term solution to sustainable transportation fuels. Biodiesel is more promising than ethanol, and the only way ethanol will really work is to find a cost-effective way to generate it from cellulose rather than from corn. Brazil's ethanol strategy works as well as it does because they produce it from sugar cane, rather than from corn or other grains, with a significant improvement in ethanol yield.

There are numerous other problems with biofuels that need to be addressed - increased fertilizer and pesticide runoff, decreased land in conservation programs (leading to likely decreases in agricultural productivity and loss of topsoil), widely distributed feedstock sources (in terms of energy content per area as opposed to the relatively high energy content per area for fossil fuels), and significant variability in feedstock production potential (severe energy impacts during drought years, for instance).

These are the technical issues, and don't address problems like we're now seeing with significant increases in prices for corn and corn-based foods (including meat).

Biofuels have a lot of promise, and do have the potential for reducing petroleum consumption. IMO, though, the first thing we should be looking at is significantly increasing our efficiency. The technologies and approaches are much more well developed, but people still want to drive the big dogs, and will as long as gasoline prices don't increase significantly.

My own view is that we need to forget about food crops as a source of biofuel in the long term. Aparently, the most energy dense feedstock is algae (http://en.wikipedia.org/wiki/Algaculture) and also the only one with the necessary scalability potential. I don't know what it costs to make a barrel of this stuff, nor the energy investment, nor the freshwater investment, nor the NOx or CO2 footprints (if anyone does know, please post), but I do know that it addresses a lot of the problems cited above. One really signifigant one remains, however, and that is that the feedstock is widely distributed, although not as widely as with ethanol.

Thanks for your help,
Rob

[sweeteviljesus]

i) there isn't that much available uranium. If all electricity in the world today was produced by nukes we'd have maybe 10-15 years' worth of economically recoverable uranium (mostly in Australia, Canada and Russia) then we have to start looking for another power source; we may as well skip that step and do that now.


Yes, but the fuel cost is not a very large part of the equation. After the cheap uranium is exhausted, we have thorium, nuclear weapon pits, high-level waste and breeder reactors available as fuel sources.


ii) the last good hope for permanent storage of high-level waste, Synroc (http://en.wikipedia.org/wiki/Synroc) or its equivalents, has recently been shown to degrade hugely faster than theory said and so we are left with no economic way of dealing with it.


It will be useful when cheap uranium runs out.



iii) a whole-cycle evaluation of carbon emissions for nukes will surely show it emits less than a coal plant, but still sizeable and I believe comparable to a natural gas powered plant. The amount generated in the building, operation, transport, and waste disposal (however you plan that) is surprisingly large; with gas all you need is a well and a pipeline, with nukes you need a huge and secure transport infrastructure.


Integrated facilities would go a long way to mitigating this problem.


iv) a nuke plant takes a minimum of 10 years to build, average more like 15. The number we would need to build to make a difference starting right now would be prohibitive, and would not start to reduce carbon emissions until they came online in over a decade - when it will substantially too late to help (and don't forget all the emissions of construction - pretty much all fossil fuel powered - have just contributed to making the problem worse before they come on line).

v) it's not as cheap as you think. Not a single nuke plant has been built anywhere in the world without substantial government subsidy, mostly in the form of free disaster insurance but also significant tax breaks especially during the long construction phase. Factor that cost in and suddenly electricity from nukes shoots up to be enormously expensive.


My hope is that technologies such as commoditized pebble-bed reactors can help mitigate this.



vi) I hardly need detail the security risks of having all that concentrated uranium shipped around the world, the expense of guarding it, and the proliferation that can result (as it is right now in Iran).

The Iranians themselves are enriching it and that is the crux of the dispute. If you want to ship fuel that gets around the proliferation problem, there is always MOX. Radiological terrorism remains a problem, however.

That said, I think that it will be at the minimum 20 years before we could convert to grid-based transportation and that is if they unveil the perfect battery powered car tomorrow.

FWIW,
Rob

[Chronos]

The only scalable carbon-neutral forms of energy production are solar and geo-thermal. Smaller but significant contributions can come from hydro, wind and tidal.This seems a very peculiar ordering. Hydro is already the cheapest power, and accounts for a significant fraction of generation. The only sense in which it's "not scalable" is that it's already scaled up to near its maximum: There are only so many places where it's economical to put in a dam. But the same is true, to a much greater degree, of geothermal. To my knowledge, the only places in the US with enough geothermal activity to make energy generation practical are Yellowstone and Hawaii. Meanwhile, photovoltaics can only just barely break even after decades of operation, and non-photovoltaic solar electricity generation can never seem to get off the ground, yet you put solar as your #1 scalable non-carbon source.

[DrDeth]

Nuclear fission also has some serious problems with waste disposal, fuel processing/reprocessing, and operational safety issues. r

Coal mining and other fossil fuel extraction kills thousands or tens of thousands of dudes yearly. Smog kills maybe 10X as many.

So far, nuclear power has yet to directly kill even one person in America. True there was Chernobyl but Chernobyl will never happen again- that sort of plant was on itway out when it happened.

[Public Animal No. 9]

The only scalable carbon-neutral forms of energy production are solar and geo-thermal.
We should keep in mind that biofuels are essentially ways to store solar energy. When you look at the efficiencies of biological conversion of solar energy to plant material, then from plant material to fuel, then fuel to motion, the overall solar-to-motion efficiency is pretty bleak. I've done a quick back-of-the-envelope calculation comparing solar energy/acre to biodiesel/acre, and that comes out to something on the order of 1%. And that's prior to any fuel-to-motion conversion.

In the long run, there will have to be a more efficient approach to producing motive power for transportation. (I haven't been able to figure out the solar-to-dinosaur-to-motion efficiency, but it seems to take a long time :p )

[Chronos]

I've done a quick back-of-the-envelope calculation comparing solar energy/acre to biodiesel/acre, and that comes out to something on the order of 1%.Yes, but switchgrass is a lot cheaper to install and maintain than solar cells or mirrors and boiler towers. And that 1% is energy in a form that's easy to store and to fill up cars with. You have to compare that efficiency with the efficiency of turning solar energy into some other practical vehicle fuel. Biodiesel may not be the best use of that acreage, but it's not as dismal (compared to other options) as you make it out to be.

[Stranger On A Train]

Coal mining and other fossil fuel extraction kills thousands or tens of thousands of dudes yearly. Smog kills maybe 10X as many.Cite and cite.

So far, nuclear power has yet to directly kill even one person in America. True there was Chernobyl but Chernobyl will never happen again- that sort of plant was on itway out when it happened.While it's that no one has ever been killed in a commercial power generating reactor in the United States (though there have been several "excursions" aside from the dramatic one at Three Mile Island, and a number of cases of radioactive leakage from fuel processing facilities) it's not true that the type of graphite moderated reactor used at the Chernobyl facility (the graphite moderated RBMK) was "on it's way out"; indeed, aside from the four reactors at Chernobyl, only one additional one of the total of thirteen constructed has been shut down, and there are at least two others still under construction.

I'm not inherently opposed to energy production by nuclear fission--I think that with more modern, failsafe designs it can be less hazardous and less expensive to operate than current plants, and reprocessing of fuel (rather than vitrification and burial) fuel supplies can be expended almost indefinately--but there are some definite techincal drawbacks in additional to the (understandable) political NIMBY issues. Ultimately, fission is not sustainable or renewable; it's a step, and a somewhat messy one, between fossil fuels (which have been instrumental in getting civilization to the point of being technically capable of recognizing the harm that carbon emissions do) and some other, more sustainable source (fusion, some kind of direct solar, et cetera). It also behooves us, in the interim, to develop more efficient habitable structures, distribution methods, and transportation systems. Waving nuclear fission as a magic wand that'll solve all problems harkens back to the good old days of HUAC, Cadillacs with ginormous tail fins, and Jackie Gleason threatening to knock his wife to the Moon.

Stranger

[DrDeth]

Cite and cite.
r

http://www.minesandcommunities.org/Action/press861.htm
"The USA averages around 30 mining deaths per year - compared to some 8,000 in China - and its safety record has been steadily improving over the past few decades."

That is 8,030 in just two nations. Two of the biggest coal mining nations, true.

http://weather.mercurynews.com/auto/mercurynews/health/pollution.asp
"utdoor air pollution in the U.S. due to particulate pollution alone was estimated by the Environmental Protection Agency (EPA) in 1997 to cause at least 20,000 premature deaths each year. Other estimates place this number at 50,000 to 100,000 deaths per year.(1) Globally, about 800,000 people per year die prematurely due to outdoor air pollution, according to a 2005 study published in the Journal of Toxicology and Environmental Health." 800,000 deaths per year from air pollution, much of it from buring coal or oil. So I was wrong- it isn;t 10's of thousands, it's 100's of thousands.

http://thisweekinnuclear.blogspot.com/2007/01/coal-and-oil-vs-nuclear.html
"# Air pollution from burning coal in the USA causes 24,000 deaths per year, including 2,800 from lung cancer. The number is much higher in nations with lower emissions standards.
# Over the last 10 years, coal mining deaths have averaged 33 deaths per year in the USA, and more than 6,000 per year in China.....Last week "hundreds" of people were burned alive when an oil pipeline caught fire. More than 1000 people have died there in the past year from similar pipeline fires. Outside of Nigeria (where it occurred) no one seems to care."

24,000 deaths per year just from coal buring just in the USA. 1000 deaths per year from oil extraction just in Nigeria.

[lowbrass]

True there was Chernobyl but Chernobyl will never happen again- that sort of plant was on itway out when it happened.
The "it will never happen" argument always falls flat to my ears. Nobody ever thinks a disaster can happen. If they did, they would prevent it. The Titanic was supposedly "unsinkable". It was supposedly impossible for the World Trade Center to fall down. You can look back at anything with 20/20 hindsight and say, "Oh yeah - that's what they did wrong; we won't do that again". But when people start saying something will "never happen", I take it with a grain of salt.

[Public Animal No. 9]

Yes, but switchgrass is a lot cheaper to install and maintain than solar cells or mirrors and boiler towers. And that 1% is energy in a form that's easy to store and to fill up cars with. You have to compare that efficiency with the efficiency of turning solar energy into some other practical vehicle fuel. Biodiesel may not be the best use of that acreage, but it's not as dismal (compared to other options) as you make it out to be.
I agree that there are good practical reasons for using biofuels in the short term (10-20 years). My point (which I didn't quite get across) was that, in the long term, finding more effective conversions from solar to useful energy will be essential. "More effective" includes energy storage, transportability, etc. And the biofuel feedstocks can provide additional benefits beyond simply energy - soil conservation, wildlife habitat, and so on. There's no easy answer, and I didn't mean to imply that there was.

[DrDeth]

The "it will never happen" argument always falls flat to my ears. Nobody ever thinks a disaster can happen. If they did, they would prevent it. The Titanic was supposedly "unsinkable". It was supposedly impossible for the World Trade Center to fall down. You can look back at anything with 20/20 hindsight and say, "Oh yeah - that's what they did wrong; we won't do that again". But when people start saying something will "never happen", I take it with a grain of salt.

Chernobyl will never happen again just like the Hindenburg disaster will never happen again. They no longer use either technology.

[Stranger On A Train]

Chernobyl will never happen again just like the Hindenburg disaster will never happen again. They no longer use either technology.Again, this is not true. There are a number of different types of graphite-moderated reactors still in operation in a variety of nations. The use of graphite-moderated designs were particularly popular with the UK Atomic Energy Authority and British Nuclear Fuels, as well as extensive use in former East Bloc nations in which many are still operated. Reactors of similar design as those at Chernobyl is still in operation in Lithuania and the Ukraine and will remain operating for the forseeable future. (One of the advantages of RMBK-type reactors and graphite moderation in general is the ability to use natural uranium or a variety of other combinations of fissible materials with minimal processing or enrichment.) The PBMR (http://en.wikipedia.org/wiki/Pebble_bed_reactor) design that is under development also uses pyrolitic graphite as a moderator, though the fuel and moderator are contained within a silicon carbide shell which (in theory) should provide containment even if the fuel element overheats and liquidizes.

Saying that "it could never happen again" is paramount to sticking one's head in the sand. There are certainly ways to make commercial nuclear fission power generation more fault tolerant and less complex, but no amount of handwaving is going to eliminate the risks and costs associated with it.

It's also noteworthy that aside from the costs in constructing nuclear power generation facilities and all of the operational costs involving fuel processing and so forth, there's also a massive end-of-life cost with decommisioning and remediation of the facilities. You can't just shut them down and break it up for recycling; there is a long, expensive, and not slightly hazardous multi-year effort in making the now-deactivated facility safe. Facilities can't be used indefinitely because structural materials in the reactor will become damaged by neutron embrittlement and corrosion/erosion from the coolant loop, which can't be serviced or replaced due to radioactive activation. (A modular reactor like a PBMR would go a long way to minimizing this problem, but other existing designs will have limits based upon how long they can survive the harsh conditions in the reactor itself, plus obsolescence of control hardware and so forth.)

Nuclear fission is not a panacea. It is, at best, a lesser-of-two-evils choice, allowing us to transition from fossil fuels to some more minimally polluting form of energy production that is still over the horizon.

Stranger

[DrDeth]

Again, this is not true. There are a number of different types of graphite-moderated reactors still in operation in a variety of nations. The use of graphite-moderated designs were particularly popular with the UK Atomic Energy Authority and British Nuclear Fuels, as well as extensive use in former East Bloc nations in which many are still operated. Reactors of similar design as those at Chernobyl is still in operation in Lithuania and the Ukraine and will remain operating for the forseeable future. (One of the advantages of RMBK-type reactors and graphite moderation in general is the ability to use natural uranium or a variety of other combinations of fissible materials with minimal processing or enrichment.) r

Graphite moderated yes (altho rare)- Chernobyl type- no. It wasn't just the graphite:
http://en.wikipedia.org/wiki/Chernobyl_disaster
* The reactor had a dangerously large positive void coefficient. The void coefficient is a measurement of how the reactor responds to increased steam formation in the water coolant. Most other reactor designs produce less energy as they get hotter, because if the coolant contains steam bubbles, fewer neutrons are slowed down. Faster neutrons are less likely to split uranium atoms, so the reactor produces less power. Chernobyl's RBMK reactor, however, used solid graphite as a neutron moderator to slow down the neutrons, and neutron-absorbing light-water to cool the core. Thus neutrons are slowed down even if steam bubbles form in the water. Furthermore, because steam absorbs neutrons much less readily than water, increasing an RBMK reactor's temperature means that more neutrons are able to split uranium atoms, increasing the reactor's power output. This makes the RBMK design very unstable at low power levels, and prone to suddenly produce too much energy if the temperature rises. This was counter-intuitive and unknown to the crew.

* A more significant flaw was in the design of the control rods that are inserted into the reactor to slow down the reaction. In the RBMK reactor design, the control rod end tips were made of graphite and the extenders (the end areas of the control rods above the end tips, measuring 1 metre in length) were hollow and filled with water, while the rest of the rod – the truly functional part which absorbs the neutrons and thereby halts the reaction – was made of boron carbide. With this design, when the rods are initially inserted into the reactor, the graphite ends displace some coolant. This greatly increases the rate of the fission reaction, since graphite is a more potent neutron moderator (a material that enables a nuclear reaction) and also absorbs far fewer neutrons than the boiling light water. Thus for the first few seconds of control rod activation, reactor power output is increased, rather than reduced as desired. This behavior is counter-intuitive and was not known to the reactor operators.

* The water channels run through the core vertically, meaning that the water's temperature increases as it moves up and thus creates a temperature gradient in the core. This effect is exacerbated if the top portion turns completely to steam, since the topmost part of the core is no longer being properly cooled and reactivity greatly increases. (By contrast, the CANDU reactor's water channels run through the core horizontally, with water flowing in opposite directions among adjacent channels. Hence, the core has a much more even temperature distribution.)

* To reduce costs, and because of its large size, the reactor had been constructed with only partial containment. This allowed the radioactive contaminants to escape into the atmosphere after the steam explosion burst the primary pressure vessel.

* The reactor also had been running for over one year, and was storing fission byproducts; these byproducts pushed the reactor towards disaster.

* As the reactor heated up, design flaws caused the reactor vessel to warp and break up, making further insertion of control rods impossible.


and
Since the

Chernobyl accident, all remaining RBMKs have been retrofitted with a number of updates for safety. The largest of these updates fixes the RBMK control rod design. Previously the control rods were designed with graphite tips, which when initially inserted into the reactor sped up the reaction, instead of slowing or stopping it. This design flaw caused the first explosion of the Chernobyl accident, when the emergency button was pressed to stop the reactor. The updates are

* An increase in fuel enrichment from 2% to 2.4%. This difference improves neutron absorption, reducing the reliance on cooling water for reactor control.
* Manual control rod count increased from 30 to 45.
* 80 additional absorbers inhibit operation at low power, where the RBMK design is most dangerous.
* SCRAM (rapid shut down) sequence reduced from 18 to 12 seconds.
* Precautions against unauthorised access to emergency safety systems.

Closures

Of the 13 RBMKs built (and one is still under construction at Kursk), all three surviving reactors at the Chernobyl plant have now been closed and one of the two reactors at Ignalina in Lithuania has shut down with the second due to close by 2010. [1]

Chernobyl was a unique accident with the quite a few human errors (which could re-occur, but not likely as the USSR is gone) and some half-dozen technical design errors, all of which have been fixed on the very few RBMK reactors still extant. Chernobyl will never happen again, it is impossible although certainly an accident of some other sort could happen. Nor will the Hindenburg disaster happen again, although of course a dirigible could still crash.

[Beware of Doug]

No it can't, because it would have to get built first.

An ancillary problem with biofuels is that there are a lot of dirtbag hippie types out there doing car conversions. My cousin had a brand new VW ruined by one of these guys. It wouldn't run on grease or diesel, and it would have cost her more to fix than just to buy another car.

[Stranger On A Train]

Chernobyl will never happen again, it is impossible although certainly an accident of some other sort could happen.You keep using that word; I do not think it means what you think it means.

While the RBMK-type reactors have all been modified to alleviate the some of the design problems that led to the fire at Chernobyl #4 (though they all still lack containment domes, so another core meltdown and fire would exhaust straight to the atmosphere as Chernobyl #4 did), and no doubt there is a greater awareness of the possibility of the procedural failures that led to the excursion and subsequent fire, it is not "impossible" for a core meltdown to occur again in these or in most other types of commercial power generating reactors, and in fact there have been a number of partial meltdown events. The inherent problems with graphite moderated reactors is the potential for graphite to combust if heated to very high temperatures in the presence of oxygen, and the fact that graphite will undergo rapid structural phase transformations (see Wigner energy (http://en.wikipedia.org/wiki/Wigner_effect)) which can make it prone to suddenly and unpredictably increasing the degree of moderation and thus the reaction rate. It is very difficult to extinguish such fires without worsening the situation. (Dumping water into the pile may moderate emitted neutrons, increasing the reaction rate.)

The Chernobyl incident is not the first time that such an accident has occured with a graphite moderated reactor; the most notable case is the fire at Windscale Pile #1 (http://en.wikipedia.org/wiki/Windscale_fire). While the Windscale piles suffered from the then-ignorance about the issues with using solid graphite moderation and a lack of containment features in the design (and mitigated, if serendipitously, by other design selections) the fact remains that graphite-moderated reactors--which are not as rare as you believe, and in fact the graphite-moderated Advanced Gas Cooled Reactor (http://en.wikipedia.org/wiki/Advanced_gas_cooled_reactor) design is the mainstay of British Energy--have some inherent risks.

Reactors that use water as a moderator can be designed to be inherently failsafe--that is, an excursion that results in excessive heat or thermal neutron production causes the reactor to passively reduce the reaction rate, whether by boiling off the moderator, changing the fuel geometry, et cetera. Some, like the CANDU reactor, meet this critiera, but most Pressurized Water Reactors and Boiling Water Reactors can become supercritical if active control systems fail or are deactivated. In fact, the reactor that suffered a Loss of Coolant Failure at Three Mile Island was a PWR type widely considered (at that time) to be one of the safest designs available. It's fortunate that the vented coolant cloud travelled over the ocean rather than land. Og help you if you should have a LOCA in a liquid metal-cooled reactor, like the one that occured at the Santa Susana Field Laboratory SRE (http://en.wikipedia.org/wiki/Santa_Susana_Field_Laboratory#Sodium_Reactor_Experiment) on a full-sized commerical reactor; the amount, extent, and duration of contamination could dwarf Chernobyl. The United States does not currently operate any liquid-metal cooled reactors, commerically or otherwise (and we've had some very narrow misses with ones we have operated) but France, Japan, and Russia all operate metal-cooled fast breeder reactors and intend to construct and develop more.

Before you continue on with such a gung-ho attitude about how "impossible" it is for an accident on the scale of Chernobyl to reoccur, I recommend that you read up on the history of nuclear fission reactors and the the multitude of near-misses (INES Level 3 or higher) that have occured with commerical or civilian experimental nuclear fission piles. We have in many cases been fortunate, rather than successful, at limiting the scale and effects of nuclear accidents.

Back to the question posed by the o.p. (which has already been adequately addressed, but I need to do something to excuse this abominable hijack that I've extended) the major problem with biofuels is one of the scale of production and attendant impact as already detailed by Public Animal No. 9. It seems unlikely that we can replace petrofuels entirely with biofuels, or at least not without some major effects, but given a current surplus in agricultural production it can, along with conservation and more efficient utilization, serve to extend existing petroleum reserves and reduce carbon emissions imbalance while using mostly existing infrastructure for distribution, and only modest modifications to existing transportation technology. Contrast that with a hydrogen-based transportation system, which will require massive changes in how it is distributed and stored and significant alterations to internal combustion engine designs. As a supplemental energy source, biofuels can provide a backup to existing fuels in a "peak oil" scenerio, giving time to develop a more ultimately viable energy production and distribution system, and with advances in biotechnology might even become a viable permanent segment in mobile energy sources that can not be effectively served by proposed petroleum replacements.

Stranger

[Askance]

The only scalable carbon-neutral forms of energy production are solar and geo-thermal. Smaller but significant contributions can come from hydro, wind and tidal.This seems a very peculiar ordering. Hydro is already the cheapest power, and accounts for a significant fraction of generation. The only sense in which it's "not scalable" is that it's already scaled up to near its maximum: There are only so many places where it's economical to put in a dam. But the same is true, to a much greater degree, of geothermal. To my knowledge, the only places in the US with enough geothermal activity to make energy generation practical are Yellowstone and Hawaii. Meanwhile, photovoltaics can only just barely break even after decades of operation, and non-photovoltaic solar electricity generation can never seem to get off the ground, yet you put solar as your #1 scalable non-carbon source.They were not ordered within the two categories.

The scalable source of geo-thermal I was thinking of is what they are calling "hot rocks"; here in Australia for instance it has turned out that a large part of the state of South Australia (50% larger than Texas) is underlain by vast areas of hot rock, and pretty much all you need to do is pump water down to it and pipe the steam up. In assuming the same would be true of significant parts of the US as the US has more geothermal activity in general. The downside is (in SA's case) it's a way away from the areas that need power, but on the other hand it can produce it in such prodigious quantities at such a small unit cost that efficiency is almost irrelevant.

As you say, hydro is pretty much maxed, not to mention that dams are being recognised as a bad idea all round.

I'm as certain as can be that solar power - whether distributed photo-voltaic or concentrated solar-thermal - will be economic in the near future, especially if we can spend on research even a tenth of what is spent on nuclear and "clean coal" research.

[Hypno-Toad]

I'm as certain as can be that solar power - whether distributed photo-voltaic or concentrated solar-thermal - will be economic in the near future, especially if we can spend on research even a tenth of what is spent on nuclear and "clean coal" research.

This will become true even if no technological improvements occur simply because coal and petroleum are finite and their price inevitably must rise to point of making solar the cheaper option. The only question is how long before it happens. 10 years? 100? 1,000? But as fossil fuels get more expensive, the market will create more incentive for solar power R&D. This will (supposedly, hopefully) create innovations that increase solar efficiency and thus make it cheaper. This of course will bring the tipping point in favor of solar over fossil fuels that much closer. There are huge assumptions here of course. Innovations in fossil fuel efficiency could keep it cheap for longer. And other power sources may play a big hand.

[sweeteviljesus]

Back to the question posed by the o.p. (which has already been adequately addressed, but I need to do something to excuse this abominable hijack that I've extended) the major problem with biofuels is one of the scale of production and attendant impact as already detailed by Public Animal No. 9. It seems unlikely that we can replace petrofuels entirely with biofuels, or at least not without some major effects, but given a current surplus in agricultural production it can, along with conservation and more efficient utilization, serve to extend existing petroleum reserves and reduce carbon emissions imbalance while using mostly existing infrastructure for distribution, and only modest modifications to existing transportation technology. Contrast that with a hydrogen-based transportation system, which will require massive changes in how it is distributed and stored and significant alterations to internal combustion engine designs. As a supplemental energy source, biofuels can provide a backup to existing fuels in a "peak oil" scenerio, giving time to develop a more ultimately viable energy production and distribution system, and with advances in biotechnology might even become a viable permanent segment in mobile energy sources that can not be effectively served by proposed petroleum replacements.

Stranger

Well, the purpose of my post was to assume that we could completely supplant petrofuels with biofuels and then ask what the new problems would be. If you attempt to use food crops, then the problems have been discussed to death. If you use only waste products, you will not have enough feedstock. Algae might be able to scale up as necessary, but at what cost? That is what I wanted to know.

On the nuclear question, where are the PBMRs? I know that they are being developed in China and South Africa, but most of the stuff I can find on them is old. What are your thoughts on their safety vis-a-vis the Wigner energy problem? I know that they run at about four times the annealing temperature of graphite, but that is not to say that it is impossible ;) for them to catch fire.

Thanks,
Rob

[Chronos]

Quoth Askance:They were not ordered within the two categories.

The scalable source of geo-thermal I was thinking of is what they are calling "hot rocks"; here in Australia for instance it has turned out that a large part of the state of South Australia (50% larger than Texas) is underlain by vast areas of hot rock, and pretty much all you need to do is pump water down to it and pipe the steam up. In assuming the same would be true of significant parts of the US as the US has more geothermal activity in general. The downside is (in SA's case) it's a way away from the areas that need power, but on the other hand it can produce it in such prodigious quantities at such a small unit cost that efficiency is almost irrelevant.

As you say, hydro is pretty much maxed, not to mention that dams are being recognised as a bad idea all round.

I'm as certain as can be that solar power - whether distributed photo-voltaic or concentrated solar-thermal - will be economic in the near future, especially if we can spend on research even a tenth of what is spent on nuclear and "clean coal" research.OK, I'm not familiar with this "hot rock" technology, nor how prevalent suitable sites would be in the US, so I'll concede that point for now. But I still think it's going to be a long, long time before solar of any sort surpasses hydro. Certainly, solar technologies are going to improve, and the rate of improvement will probably increase as fossil fuels run out. But hydro has a huge head start, both in existing power capability and in price, and even with accelerated development, it'll take a while for solar to catch up. And by that time, who knows, we may have already developed practical fusion, or somesuch.

[Stranger On A Train]

Well, the purpose of my post was to assume that we could completely supplant petrofuels with biofuels and then ask what the new problems would be. If you attempt to use food crops, then the problems have been discussed to death. If you use only waste products, you will not have enough feedstock. Algae might be able to scale up as necessary, but at what cost? That is what I wanted to know.I don't know that anybody has a true handle on the costs, or the extent that production could be scaled to, other than that existing methods of production could only be supplimental rather than a replacement. But the benefits of being able to use the existing distribution architecture and current engine designs with minimal modifications goes a long way to providing viability and justification even if the production of biofuels isn't itself cost competitive with other energy production methods.

On the nuclear question, where are the PBMRs? I know that they are being developed in China and South Africa, but most of the stuff I can find on them is old. What are your thoughts on their safety vis-a-vis the Wigner energy problem? I know that they run at about four times the annealing temperature of graphite, but that is not to say that it is impossible ;) for them to catch fire.The United States and Great Britain have demurred from developing new reactor designs owing to the cost of funding research, public scrutiny, and political inclination away from nuclear power. Western Europe, with limited natural resources and increaing population density, has traditionally been more amenible to nuclear fission energy production, though the catastrophe at Chernobyl threw a heavy cloud over that, and a residual effect of the United States enticing or essentially forcing nations of Western Europe (Turkey, West Germany, the Neatherlands, Belgium, Itally) to allow the installation of tactical and intermediate range nuclear-armed ballstic missiles has created or at least exacerbated movements to rid European nations of nuclear technology of any sort. The peoples of the former Soviet Union and republics thereof had (or more properly, were not allowed to have) such scruples, and these nations are now heavily dependant upon existing nuclear power installations, but while one of the focuses of the PBR design is safety, the Soviets were more concerned about plutonium production and extraction for nuclear weapons, and as a result of that and the subsequent poverty and lack of ongoing research they haven't gone into more advanced deisgns. China, on the other hand, is very interested in advancing and expanding their power generating capability, and both their burgening, cash flush economy and lack of existing, mature infrastructure allows them to go in more progressive directions. South Africa, with its desperate need for desalination capability, is in a similar place.

From a techincal standpoint, PBMR designs are highly attractive; they offer a high degree of passive safety, protective encapsulation of fuel elements and resultant waste, the ability to use a working gas which is both nearly thermodynamically ideal and functions at low pressure with essentially no corrosion issues, and offers ready modularity and expandability that can't be done with standard "rod and pool" designs. The downsides are the size of the pile, which has to be very large because of the low energy density (though the lack of complexity in plumbing, cooling and heat exhanger systems, and handling mechanisms probably makes this a wash), and the cost and required quality control of fuel element production as opposed to existing unclad elements is much higher, possibly by an order of magnitude. This also produces substantially more depleted (but still radioactive) high level waste, which is a significant problem if you insist on transporting it to a central site like Yucca Mountain, but perhaps not so much if you use on-site expandable storage. Reprocessing would also be essentially out of the question, or at least dramatically more difficult and producing a large volume of high level waste products, so PBMR is really the best approach only for a once-through fuel cycle. The Wigner energy problem is essentially a non-issue with PBMR even if it occured; owing to the low energy density even an uncooled pile is unlikely to attain meltdown temperatures, particularly with the silicon carbide coating.

However, in general with nuclear fission power, even if you resolve all other safety issues with the reactor itself you still have issues with the processing and reprocessing or reduction/storage/disposal of waste products. Because processing and reprocessing require labor intensive procedures and use caustic substances that require vigilance and dutiful preventative maintenance, these processes are the most likely to result in accidents and release, such as occured at the Mayak processing facility (http://en.wikipedia.org/wiki/Mayak) that contaminated hundreds of square miles and forced the evacuation of the town of Kyshtym and surrounding areas in 1957, and is now classified as a INES Level 6 nuclear accident.

Nuclear fission offers an alternative to carbon-producing fossil fuel power production, but it has its significant drawbacks as well.

Stranger

[sweeteviljesus]

I don't know that anybody has a true handle on the costs, or the extent that production could be scaled to, other than that existing methods of production could only be supplimental rather than a replacement. But the benefits of being able to use the existing distribution architecture and current engine designs with minimal modifications goes a long way to providing viability and justification even if the production of biofuels isn't itself cost competitive with other energy production methods.


I didn't mean cost in terms of price per barrel, I meant in terms of things like increased water usage. In other words, would biofuels be sustainable?


and the cost and required quality control of fuel element production as opposed to existing unclad elements is much higher, possibly by an order of magnitude. This also produces substantially more depleted (but still radioactive) high level waste, which is a significant problem if you insist on transporting it to a central site like Yucca Mountain, but perhaps not so much if you use on-site expandable storage. Reprocessing would also be essentially out of the question, or at least dramatically more difficult and producing a large volume of high level waste products, so PBMR is really the best approach only for a once-through fuel cycle.

However, in general with nuclear fission power, even if you resolve all other safety issues with the reactor itself you still have issues with the processing and reprocessing or reduction/storage/disposal of waste products. Because processing and reprocessing require labor intensive procedures and use caustic substances that require vigilance and dutiful preventative maintenance, these processes are the most likely to result in accidents and release, such as occured at the Mayak processing facility (http://en.wikipedia.org/wiki/Mayak) that contaminated hundreds of square miles and forced the evacuation of the town of Kyshtym and surrounding areas in 1957, and is now classified as a INES Level 6 nuclear accident.

Nuclear fission offers an alternative to carbon-producing fossil fuel power production, but it has its significant drawbacks as well.

Stranger

How much does it cost to make a pebble? How many pebbles in a 1GW reactor? How long is their life?

Also, two criticisms of the PBMR are that the pebbles can crack (from the buildup of Radon?) and that the pebbles can get stuck removing them. Are these real issues? If so, can they be mitigated?

What can be done about the fuel cycle in terms of processing and dealing with spent fuel?

Thanks for your help,
Rob

[Freezair SilverEye]

Going back to algae, where would said algae be harvested from? Would producers of algae-based biofuels "farm" it or would it be skimmed "from the wild," as it were? I would have significant problems with the former, as algae is a significant link in the food chain of just about every pond or lake or ocean it's found in, though algae buildups and blooms can and do happen. I don't know what scraping said blooms down would give you in terms of biofuel, but I get worried when we start mucking with ecosystems. I'd like to hope that no intelligent scientist would propose skimming up wild algae, but I honestly don't know how horrible or harmless attacking an algae bloom would be. (And I'd like to think we wouldn't go after ordinary, non-blooming ponds!) I'm usually not very good at gauging large-scale impacts, thought the idea of it makes me rather worried. If anybody has any reliable numbers/facts about the relationship between algae and pond/river/ocean ecosystems, do link me and set me aright!

Still, I have to ask where and how one would "farm" algae. True, if you've got standing water, you'll have a harder time not getting algae to grow. (I've been around too many backyard pools not to know this.) But would there be enough algae in simple, average standing pools to make a significant harvest? Or would "algae farms" be needed? Then we could have a problem akin to having to make more space for biofuel crops, and there's only so much crop space out there. Of course, algae could be grown in large tanks in buildings, but you'd still have to put those buildings somewhere. And again, how much algae do you need to make a suitable amount of biofuel?

[kunilou]

Going back to algae, where would said algae be harvested from? Would producers of algae-based biofuels "farm" it or would it be skimmed "from the wild," as it were? I would have significant problems with the former, as algae is a significant link in the food chain of just about every pond or lake or ocean it's found in, though algae buildups and blooms can and do happen. I don't know what scraping said blooms down would give you in terms of biofuel, but I get worried when we start mucking with ecosystems. I'd like to hope that no intelligent scientist would propose skimming up wild algae, but I honestly don't know how horrible or harmless attacking an algae bloom would be. (And I'd like to think we wouldn't go after ordinary, non-blooming ponds!) I'm usually not very good at gauging large-scale impacts, thought the idea of it makes me rather worried. If anybody has any reliable numbers/facts about the relationship between algae and pond/river/ocean ecosystems, do link me and set me aright!

Still, I have to ask where and how one would "farm" algae. True, if you've got standing water, you'll have a harder time not getting algae to grow. (I've been around too many backyard pools not to know this.) But would there be enough algae in simple, average standing pools to make a significant harvest? Or would "algae farms" be needed? Then we could have a problem akin to having to make more space for biofuel crops, and there's only so much crop space out there. Of course, algae could be grown in large tanks in buildings, but you'd still have to put those buildings somewhere. And again, how much algae do you need to make a suitable amount of biofuel?

Most of the development work right now is taking place on "farms" -- controlled environments with specific species of algae. Here's one of the more exotic ideas. (http://www.stltoday.com/stltoday/news/stories.nsf/sciencemedicine/story/5F3E12F5EB7C5E34862572F70007B128?OpenDocument)

[Askance]

Quoth Askance:OK, I'm not familiar with this "hot rock" technology, nor how prevalent suitable sites would be in the US, so I'll concede that point for now. But I still think it's going to be a long, long time before solar of any sort surpasses hydro. Certainly, solar technologies are going to improve, and the rate of improvement will probably increase as fossil fuels run out. But hydro has a huge head start, both in existing power capability and in price, and even with accelerated development, it'll take a while for solar to catch up. And by that time, who knows, we may have already developed practical fusion, or somesuch.Solar doesn't have to surpass hydro; hydro is as it is and there's nothing much we can do to improve or extend it. Solar doesn't have to compete with it, it has to compete with the technologies it is looking to replace, primarily burning fossil fuel but also nuclear.

As for hot rocks:

Greener than wind or solar, geothermal energy gets little attention—even though, as Nick Schulz writes, it could provide 2,000 times our current power needs. (http://www.american.com/archive/2007/may-june-magazine-contents/hot-rocks-cool-technology)

Earth continuously heats the rock deep below the surface; a new report from M.I.T. suggests harvesting that renewable energy (http://www.sciam.com/article.cfm?articleID=517E9954-E7F2-99DF-36C206BCA2D4E3C5)

[Stranger On A Train]

I didn't mean cost in terms of price per barrel, I meant in terms of things like increased water usage. In other words, would biofuels be sustainable?That all depends on what (various) methods are used to produce biofuels. My SWAG on it is that, no, biofuels would not be sustainable, in the sense of replacing existing petrofuel, but that they could supplant and/or become a niche fuel for applications where other alternatives (grid mass transit, eletric battery, hydrogen fuel cell, et cetera) may not fit the bill. I suspect that biodiesel will be more expensive than the current costs of petroleum fuels, but not by an order of magnitude.

It's interesting that you bring up water usage, because both the usage of water and thermal pollution of natural bodies of water are significant concerns that don't receive the attention they deserve. Availability of fresh, potable water is going to become a significant environmental issue, particuarly in arid regions where the depletion of natural aquifers is increasingly significant. The availability of water for irrigation to crops for food or fuel is a serious consideration, and one that is difficult to quantify at this point.

How much does it cost to make a pebble? How many pebbles in a 1GW reactor? How long is their life?

Also, two criticisms of the PBMR are that the pebbles can crack (from the buildup of Radon?) and that the pebbles can get stuck removing them. Are these real issues? If so, can they be mitigated?

What can be done about the fuel cycle in terms of processing and dealing with spent fuel?I don't know how to answer the first set of questions. My reference text (Nuclear Reactor Engineering, Samual Glasstone, although I see there's a new edition I need to check into) doesn't go deeply into costs of different types of next generation systems. The lifespan of an element is probably something like 2-3 years, and because you are constantly cycling elements through the pile you can ideally get nearly optimal usage (as compared to fuel rod bundles where you have to pull the bundle before the inner elements "poison" the reactions by absorbing too many neutrons). The number of pebbles depends on several factors including size, degree of enrichment, et cetera.

Cracking is a real issue; any manufactured product will have defects, and the thermal stresses that the pellets will see will exacerbate these. I don't have a simple answer for that other than to maintain high quality control standards and implement containment structures and protocols that limit the amount of damage or contamination a fractured element could do. I think the problem of a jammed element could be mitigated by redundantly safe design.

Issues with processing and disposal or reprocessing of spent fuel remain. With PBMR, there's a larger volume of high level waste than other systems, and as previously mentioned, it's not readily capable of being reprocessed. The total amount of radioactivity is about the same, however. With the PBMR concept, reprocessing is basically out of the question; the radioactive elements comprise only a small fraction of the total mass and bulk, and it would be very difficult to sort them out. On the other hand, reprocessing and enrichment are laborous, time-consuming, and potentially hazardous processes (due to procedures and volitile chemicals used) where as PBMR pebble elements can be formed of low grade enriched and even thorium, so the economics and safety of a "once-through" cycle are not as unappealing as it might seem, and the fact that, if the fuel elements are intact at the end of the use cycle, they're already self-contained and require no processing.

I think that transporting high level wastes to a central underground repository like Yucca Mountain is more of a political "out of sight, out of mind" solution rather than a good technical one; on-site storage eliminates the (significant) hazards of interstate transportation and provides a way to measure leakage and contamination. But of course, people want a nuclear waste depot in their backyard even less than they want a nuclear power plant.

Nuclear fission power is viable, and probably unavoidable; but in the end, improving efficiency (especially in transportation, residential and commerical structures, and appliances) combined with more ultimately sustainable energy sources (solar, geothermal, wind, nuclear fusion when-and-if that is viable) should be the goal we move toward. I have to admit not having more than a passing familiarity with "hot rocks"-type geothermal, but I have some doubts about the viability, both from a cost and environmental standpoint, of drilled down to the mantle. One could readily tap into thermal differences in the ocean, too, but despite many schemes proposed, none seem to cope with the practical difficulties of profitably extracting energy while dealing with the technical problems of working in that environment. I have my doubts that geothermal energy is going to provide more than a tiny fraction of total energy requirements.

Stranger

[sweeteviljesus]

Has anyone heard of using old oil wells for geothermal energy extraction? Is this the same as "hot rocks"? I read an article about it, but I don't remember where.

Thanks,
Rob

[Inspector Clouseau]

Hello. new here. Maybe this fella has stumbled on to something whilst looking for a cure for cancer after his daughter was diagnosed with it. If he is for real, he just may have made a major discovery.
http://www.youtube.com/watch?v=Lud1qceKqyQ&eurl=http%3A%2F%2Fwww%2Egoogle%2Ecom%2Fsearch%3Fhl%3Den%26q%3DKanzius%252C%2B%26btnG%3DGoogle%2BSear ch

[Askance]

Has anyone heard of using old oil wells for geothermal energy extraction? Is this the same as "hot rocks"? I read an article about it, but I don't remember where.I suspect you may be conflating two things here; in general places where oil is are not geo-thermally active, for obvious reasons. If you see the two articles I links a few posts ago, you have to drill down a long way (~4km) to get to hot rocks (except the huge one found in South Australia recently, that's unusually shallow), deeper than most oil wells. Most of the cost is in the drilling.

[Cyberhwk]

the price of tequila would skyrocket again like back in 2001.DEAR GOD...NO!!! :eek: :eek: :(

:D

[Una Persson]

One approach to improve the system is genetically altering the plants so that every part of the plant is usable. This really helps but I have not heard if it has been successful or not.

Martin, you seem to have hit the nail on the head on the confusing nature of the issue. The straight dope on bio-fuels seems to depend on who you want to believe. And yes, it is highly debated topic that gets spun very heavily.
I can't post on it because I've signed an NDA, but my company is right now designing an ethanol production plant which appears to be substantially energy positive. However, the capital cost does not appear to me that it will have a payback any time soon unless gasoline stays near $4 a gallon or higher. Nonetheless, it's serious enough that folks are thinking to break ground in less than 3 months.

When I was in Europe last week, I met with a large company which is betting the farm on biodiesel production from rapeseed, and their calculations are showing a very large net energy production from the process. Thanks to the regulatory environment they're in, they feel like they themselves can eventually supply 15% of their entire country's motor fuel, although they will need to import rapeseed from other countries, such as the US...and if the US is busy making its own biodiesel, then it may be a case of too much demand for too little raw material. I wasn't there to talk about biofuels, so I didn't get any details of their process, although I did get to tour their laboratory and see and smell biodiesel in different levels of production. No souvenirs, though. Damn.

[lowbrass]

Chernobyl will never happen again just like the Hindenburg disaster will never happen again. They no longer use either technology.
But to say Chernobyl will never happen again is not to say a nuclear accident can never happen again.

[scm1001]

T
The scalable source of geo-thermal I was thinking of is what they are calling "hot rocks"; here in Australia for instance it has turned out that a large part of the state of South Australia (50% larger than Texas) is underlain by vast areas of hot rock, and pretty much all you need to do is pump water down to it and pipe the steam up.

sorry the greens would never let you use geothermal as the earths core is heated by nuclear energy. :)

[Hypno-Toad]

When I was in Europe last week, I met with a large company which is betting the farm on biodiesel production from rapeseed, and their calculations are showing a very large net energy production from the process. Thanks to the regulatory environment they're in, they feel like they themselves can eventually supply 15% of their entire country's motor fuel, although they will need to import rapeseed from other countries, such as the US...and if the US is busy making its own biodiesel, then it may be a case of too much demand for too little raw material. I wasn't there to talk about biofuels, so I didn't get any details of their process, although I did get to tour their laboratory and see and smell biodiesel in different levels of production. No souvenirs, though. Damn.
I've heard that soybeans give a much greater return than corn in terms of bio-diesal (or ethanol. Damn memory).