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Old 03-25-2020, 05:25 PM
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Global warming -- Check my math/reasoning please.


I've been reading some articles about a research paper.
(links are to an article in NRC (Dutch, soft paywall), Arstechnica and the research paper is from Nature (paywall))

The conclusion of this research seems to be that electric cars and efficient electric heating are a net benefit when some part of the used electricity has low carbon emissions.

That can't be right. (tell me where I am making a mistake!)

For the purpose of this thread I've created a simple model of a country:
in this country 1/3 of all energy is consumed by transportation, 1/3 is consumed heating houses and 1/3 is used generating electricity. The goal is to do this with 0 emissions, and reduce emissions as efficiently as possible along the way (to 0 emissions).

If this country converts 50% of its electricity generation to something with zero emissions they will have reduced their carbon footprint by 1/6. Then they replace 50% of their cars with EVs. Again 1/6 reduction! Wait, where does that power come from?
How is it beneficial for their emissions to start to use more electricity? As long as not ALL generated power is "Green" this makes 0 sense to me. Electrical cars (EV) use about as much power as a normal household so the extra power needed is not insignificant. In these articles/research the electrical power is treated as if it is just there, ignoring that that power has to be generated somehow.
In the articles/research they calculate with whatever "mix" is available(in my example 50% renewable) Then they conclude electrical cars are 50% cleaner. Here I stop understanding basic math. We have to add capacity to allow for all that extra power: this comes 100% from conventional generation. If you don't plug in your car, the coal-fired plant has to burn less coal. Not 50%, 100% of the extra power comes from the least clean source, the one you could close if demand was just a little less. If you lose the electrical cars you can lose the coal plant. This remains true until all generated power has better thermal efficiency as a car. Introducing the electrical cars is carbon neutral in the bad sense: It is great for air quality in cities, for the planet: meh.
I hope I'm missing something. (All kinds of policy and subside is based on me being wrong) Can someone explain what I'm missing?

Some fun figures:
Thermal efficiency of
internal combustion engine(ICE): 20-35%
Coal fired power plant 35%
combined cycle gas plant 60%

electrical losses
in transportation 5%
in charging 7%
in discharging 15%
(numbers are rounded-- I think fairly)
That leaves an EV on roughly the same efficiency as an ICE)

This is not an argument against EVs: Some R&D in charging infrastructure and production has to be done now, ahead of sufficient renewable sources. I just want to emphasize that they should be treated as such (R&D) not as a meaningful measure to reduce carbon emissions now. Our main focus should lie with replacing all conventional production of electricity with zero carbon alternatives, insulating houses, improving efficiency of transportation (hybrids? smaller cars? public transport?)
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Old 03-25-2020, 05:32 PM
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Even if all of the electricity powering your car came from coal, coal plants are enough more efficient than car engines that it's still a net positive. But it won't all come from coal. Windmills are sometimes shut off when demand is low. Increase the demand at those times, and you can keep the windmills running. This works especially well with loads like charging a car's batteries, that don't have to be done at a specific time, and can be smart-metered to when there's excess capacity.
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Old 03-25-2020, 05:41 PM
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There is also the energy cost of transportation of the gas to the gas station, since it relies on ground road transportation rather than pipes or trains, as well as the energy spent driving to a gas station rather than charging at home or work.
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Old 03-25-2020, 06:20 PM
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There is also the energy cost of transportation of the gas to the gas station, since it relies on ground road transportation rather than pipes or trains, as well as the energy spent driving to a gas station rather than charging at home or work.
The most persuasive argument for electric transportation vehicles is that it is the most fungible of all alternatives to petrochemical-powered vehicles; wherever we can produce electricity, it can be used for transportation, and as those sources change over time (more solar, clean natural gas, propane, 4th gen nuclear fission, eventual nuclear fusion) the cars will work the same. This will require massive improvements to our electric power distribution infrastructure, but we are overdue for that anyway from both and efficiency and security perspective.

The problem, however, is that the material resources need to built electric motors and electrochemical batteries are the Achilles heel; copper, lithium, and the various rare earth minerals need to build powerful magnets and catalysts are limited in availably and very polluting to mine. We're going to have to figure out how to do more with less; both more efficient use of materials (or alternatives like superconducting quenched carbon...if it can actually be produced) and fewer vehicles overall.

Getting back to the o.p., while it is certainly desirable to develop and implement zero carbon emitting power production, we also need to consider methods we can deploy in the very near term that may not have zero carbon emissions but will at least produce energy with a substantially lower carbon footprint while allowing for a transition to future carbon-free energy sources. We also need to consider the cradle-to-grave emissions and cost; many nuclear fission power production advocates like to promote the fact that the fission process itself produces no carbon emissions, but there are substantial extra energy costs in separation, enrichment and fuel production for the once-thru cycle, high embedded carbon in pressurized and boiling water reactors with thousands of tons of steel and concrete, large transportation carbon footprints, and of course the other downsides that have plagued the nuclear power industry into not being competitive including the uranium mining and resulting environmental pollution, spent fuel handling and disposal, and plant retirement costs including the disassembly and removal of radioactive materials.

This doesn't mean that nuclear fission power production shouldn't be part of a future energy portfolio, and in fact it is unavoidable, but it does argue for the development of better fuel cycles requiring less processing and enrichment and with partial or 'complete' burnup of actinides, less protective infrastructure and elaborate "fail-safe" systems, and more modular design that doesn't require such expensive site-specific modification. And we also need to have an array of other sources in our portfolio, as well as mechanisms to encourage or subsidize investment (particularly in photovoltaic solar power for which production costs have dropped so low that there is actually too much competition for market stability) and better methods for bulk energy storage of surplus power to be available in peak hours. And, of course, investment in controlled nuclear fusion with realistic timelines and goals.

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Old 03-25-2020, 06:24 PM
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Even if all of the electricity powering your car came from coal, coal plants are enough more efficient than car engines that it's still a net positive. But it won't all come from coal. Windmills are sometimes shut off when demand is low. Increase the demand at those times, and you can keep the windmills running. This works especially well with loads like charging a car's batteries, that don't have to be done at a specific time, and can be smart-metered to when there's excess capacity.
A coal fired plant is roughly as efficient as a very efficient car(around 35% thermal efficiency) . Until you take into account that you lose 5% of that energy before it reaches your house, then before you start powering the the electrical motor you lose another 20%. Then your motor is not 100% efficient: call it 95%: Putting the coal plant + EV on par with a normal car. Still great for reducing smog/noise in urban areas, but polar bears don't care about that.

About the smart metering. Does that exist where you live?
As an engineer I love the idea:we could (should!) use the EVs to store excess power and feed it back when needed. We only need to develop some standards for communicating that stuff to the car and its charger while still guaranteeing you have enough range in the morning.
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Old 03-25-2020, 06:28 PM
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There is also the energy cost of transportation of the gas to the gas station, since it relies on ground road transportation rather than pipes or trains, as well as the energy spent driving to a gas station rather than charging at home or work.
As long as both the electricity plant and the car are reliant on fossil fuel I think that is a wash.
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Old 03-25-2020, 07:30 PM
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The numbers I've seen put a significantly higher efficiency on the coal plant (mostly because they can operate at higher temperatures), and while both have losses in transportation, they pale in comparison to the inefficiencies of the respective heat engines.

It'd take me a while to dig out my environmental physics textbook, though.
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Old 03-25-2020, 08:03 PM
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As long as both the electricity plant and the car are reliant on fossil fuel I think that is a wash.
It appears that there are around four thousand fossil fuel power plants in the US. I suspect each of these can store a rather large amount of source fuel on site. By contrast, there are around a hundred million vehicle fueling stations, each of which can typically store maybe a few score to a couple hundred thousand gallons of fuel for sale.

This means that the cracked fuel for vehicles has to first be moved in large quantities to distribution depots, then regularly shipped out to individual filling stations, as opposed to being shipped once, in large amounts, to the generating facilities.

Fuel trucks add traffic to the roads, causing a little more fuel to be used by concurrent road traffic, and are somewhat to a lot less efficient than rail cars going to the generating plant.

So, no, I do not believe that it is wash.
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Old 03-25-2020, 08:21 PM
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The numbers I've seen put a significantly higher efficiency on the coal plant (mostly because they can operate at higher temperatures), ...
Many operating coal plants are supercritical coal plants (higher temps) and have efficiency in the 40-45 % range.

Here is a ready reference for you : https://energyeducation.ca/encyclope...cal_coal_plant
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Old 03-25-2020, 08:27 PM
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The most persuasive argument for electric transportation vehicles is that it is the most fungible of all alternatives to petrochemical-powered vehicles; wherever we can produce electricity, it can be used for transportation, and as those sources change over time (more solar, clean natural gas, propane, 4th gen nuclear fission, eventual nuclear fusion) the cars will work the same. This will require massive improvements to our electric power distribution infrastructure, but we are overdue for that anyway from both and efficiency and security perspective.

The problem, however, is that the material resources need to built electric motors and electrochemical batteries are the Achilles heel; copper, lithium, and the various rare earth minerals need to build powerful magnets and catalysts are limited in availably and very polluting to mine. We're going to have to figure out how to do more with less; both more efficient use of materials (or alternatives like superconducting quenched carbon...if it can actually be produced) and fewer vehicles overall.

Getting back to the o.p., while it is certainly desirable to develop and implement zero carbon emitting power production, we also need to consider methods we can deploy in the very near term that may not have zero carbon emissions but will at least produce energy with a substantially lower carbon footprint while allowing for a transition to future carbon-free energy sources. We also need to consider the cradle-to-grave emissions and cost; many nuclear fission power production advocates like to promote the fact that the fission process itself produces no carbon emissions, but there are substantial extra energy costs in separation, enrichment and fuel production for the once-thru cycle, high embedded carbon in pressurized and boiling water reactors with thousands of tons of steel and concrete, large transportation carbon footprints, and of course the other downsides that have plagued the nuclear power industry into not being competitive including the uranium mining and resulting environmental pollution, spent fuel handling and disposal, and plant retirement costs including the disassembly and removal of radioactive materials.

This doesn't mean that nuclear fission power production shouldn't be part of a future energy portfolio, and in fact it is unavoidable, but it does argue for the development of better fuel cycles requiring less processing and enrichment and with partial or 'complete' burnup of actinides, less protective infrastructure and elaborate "fail-safe" systems, and more modular design that doesn't require such expensive site-specific modification. And we also need to have an array of other sources in our portfolio, as well as mechanisms to encourage or subsidize investment (particularly in photovoltaic solar power for which production costs have dropped so low that there is actually too much competition for market stability) and better methods for bulk energy storage of surplus power to be available in peak hours. And, of course, investment in controlled nuclear fusion with realistic timelines and goals.

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Old 03-25-2020, 08:27 PM
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This means that the cracked fuel for vehicles has to first be moved in large quantities to distribution depots, then regularly shipped out to individual filling stations, as opposed to being shipped once, in large amounts, to the generating facilities......
The energy density of gasoline is very high compared to car batteries.

I own a Tesla and in the short time I have owned it, I have had 3 flat tires one of them needing tire replacement. Electric cars are heavy and weight of the battery they have to lug around beats the energy needs of transporting gasoline from storage to fuel stations.
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Old 03-25-2020, 09:32 PM
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The energy density of gasoline is very high compared to car batteries.
Looking around, it seems as though the low-end model 3, with a supposed range of 260 miles, contains the energy equivalent in gasoline that would get my '05 Focus about 55 miles. So my pretty good little car, driven by a person who does a bit of hypermiling, is still wasting 5 times as much energy as an electric car.
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Old 03-25-2020, 09:34 PM
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The numbers I've seen put a significantly higher efficiency on the coal plant (mostly because they can operate at higher temperatures), and while both have losses in transportation, they pale in comparison to the inefficiencies of the respective heat engines.
There is also the fact that the electric generating plant is a point source, compared to hundreds of cars wandering about the roads. An effective pollution control system can be installed on the plant, and upgraded as better systems are developed. But pollution controls on cars aren't very effective, are seldom maintained, and can't easily be upgraded when scattered on hundreds of cars. (Assuming they aren't stolen -- in my neighborhood emails, there are reports a couple times a week of someone having their catalytic converter stolen out from under their vehicle.)
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Old 03-25-2020, 10:24 PM
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It appears that there are around four thousand fossil fuel power plants in the US. I suspect each of these can store a rather large amount of source fuel on site. By contrast, there are around a hundred million vehicle fueling stations, each of which can typically store maybe a few score to a couple hundred thousand gallons of fuel for sale.
No. 100,000 not 100,000,000
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Old 03-25-2020, 11:22 PM
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Electrical cars (EV) use about as much power as a normal household...
More like half. For example, the EPA rated efficiency of the Tesla Model-3 is 26 kWh per 100 miles. The aveage American drives 16,550 miles per year, so allowing 7% inefficiency for charging, that's 4600 kWh per year. The average household electricity usage is about 11,000 kWh.


Quote:
Some fun figures:
Thermal efficiency of
internal combustion engine(ICE): 20-35%
Coal fired power plant 35%
combined cycle gas plant 60%

electrical losses
in transportation 5%
in charging 7%
in discharging 15%
(numbers are rounded-- I think fairly)
That leaves an EV on roughly the same efficiency as an ICE)
I think you'll find that the 20-35% efficiency for ICE is the maximum, not average. Car engines are hardly ever operating at optimal efficiency, while power plants usually are. Also, electric cars have other tricks to improve efficiency - they don't waste any power when stopped in traffic, and they have regenerative braking.

Also, that "discharging" inefficiency is already part of the car's efficiency number. I'm not sure about the charging, but let's assume it's not.

So a Tesla Model-3 requires 26 kWh per 100 miles. Factor in those inefficiencies, and you need 26 kWh/ 0.95 / 0.93 = 29.4 kWh per 100 miles at the power plant. Assuming 35% thermal efficiency coal plant, we need 29.4 kWh / 0.35 = 84 kWh of thermal energy per 100 miles. With the 60% efficient combined-cycle natural gas plant, it's 49 kWh per 100 miles.

I'm not sure what you would consider to be an ICE equivalent of a Tesla Model-3, but I'd assume a Toyota Corolla at 34 mpg combined = 3.0 gallons per 100 miles. 1 gallon of gasoline contains 33.4 kWh of energy, so that's 100 kWh per 100 miles. I.e. a Tesla model-3 + coal power plant has a 19% better thermal efficiency than a Toyota Corolla. The natural gas plant is 104% more efficient. So the claim of 50% more efficiency is plausible assuming a mix of these power plants.

And here I'm just using your numbers, I haven't checked to see if those are correct.

This also ignores all the inefficiencies of producing gasoline. How much crude oil do you need to deliver 1 gallon of gasoline to the customer? Including transportation of crude oil, energy used by the refinery, and transportation cost of the refined gasoline? Of course fuel for power plants need transport as well, but not nearly as much processing, and all the transportation is in bulk, which improves efficiency.

Last edited by scr4; 03-25-2020 at 11:27 PM.
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Old 03-25-2020, 11:36 PM
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p.s. If we instead assume a 52 mpg Toyota Prius, that seems more efficient than coal power plants, though not as good as natural gas. So if you live in an area where most of your electricity comes from coal, and don't expect that to change for the next 10+ years (however long you plan to keep the car), then a Prius may be a more environmentally friendly choice than the Tesla.
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Old 03-26-2020, 12:29 AM
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No. 100,000 not 100,000,000
My mistake. I thought the number seemed high.

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p.s. If we instead assume a 52 mpg Toyota Prius, that seems more efficient than coal power plants, though not as good as natural gas. So if you live in an area where most of your electricity comes from coal, and don't expect that to change for the next 10+ years (however long you plan to keep the car), then a Prius may be a more environmentally friendly choice than the Tesla.
Except, you have to factor in the extra fuel transportation/distribution step to the filling station for the Prius (most of which are not the plug-in model), so they still come out a little behind.
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Old 03-26-2020, 08:17 AM
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Quoth Tim@T-Bonham.net:

There is also the fact that the electric generating plant is a point source, compared to hundreds of cars wandering about the roads. An effective pollution control system can be installed on the plant, and upgraded as better systems are developed.
Well, yes and no. That works fine if the pollutants we're talking about are sulfur oxides, or nitrogen oxides, or ozone. But nobody's ever come up with a practical way to deal with the number one pollutant, the carbon dioxide.
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Old 03-26-2020, 08:36 AM
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Well, yes and no. That works fine if the pollutants we're talking about are sulfur oxides, or nitrogen oxides, or ozone. But nobody's ever come up with a practical way to deal with the number one pollutant, the carbon dioxide.
That is not strictly true; there are a number of technologies in various states of development for the direct capture of CO2 suitable for point of emission carbon capture and sequestration like this one. However, in order to turn the carbon into a form that can be permanently sequestered requires significant energy input that detracts from the net energy output of the plant. And coal is already becoming as or more expensive than natural gas while the primary method for extracting coal (mountaintop removal which replaced the more dangerous longwall mining in the ‘Eighties) has become very unpopular with both conservationists and the people who are directly affected by pollution and landslides. The United States has large reserves of natural gas, and estimates of global natural gas reserves are enormous, so coal (“clean” or otherwise) is going away regardless.

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Old 03-26-2020, 09:13 AM
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That's why I said no practical way. There are plenty of impractical ways to do it.
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Old 03-26-2020, 09:33 AM
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That's why I said no practical way. There are plenty of impractical ways to do it.
Not sure why you say that. Urea (fertilizer made by reacting ammonia with CO2) has been made worldwide for many many decades now and is a very practical nitrogen fertilizer.

Also Methanol (dehydrates to make DME, a popular fuel in China) manufacture benefits from increased CO2 and they often buy CO2.

But all this pales for the scale of CO2 capture and you are right there.
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Old 03-26-2020, 10:12 AM
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The OP is correct to say that widespread use of EVs will require additional electricity generating capacity. But looking at this cost comparison, wind and natural gas are cheaper than coal. So if/when EVs become more widespread, it's likely that they would mostly be powered by natural gas and wind, not coal. In the sense that the additional electricity needed for EVs would mostly come from wind and natural gas.

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Old 03-26-2020, 10:17 AM
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That's why I said no practical way. There are plenty of impractical ways to do it.
The issue isn’t that it is “impractical” in any technical sense; it just isn’t fiscally viable for an industry that is already in decline and is essentially just retiring plants. It is still a potentially viable method of carbon capture for natural gas and industrial processes like basic oxygen steel production, and the extracted carbon can be used to produce dimethyl ether as am77494 notes (although not on a scale that would be able to replace all use in diesel applications) and urea per the Kansai Mitsubishi Carbon Dioxide Recovery Process.

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Old 03-26-2020, 10:37 AM
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There is also a rather effective carbon capture method that is not at all technologically difficult.
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Old 03-26-2020, 10:56 AM
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There is also a rather effective carbon capture method that is not at all technologically difficult.
Cows?
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Old 03-26-2020, 10:58 AM
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Urea production is practical for making urea. It isn't practical for sequestering carbon.

eschereal, if you're referring to growing plants, sure, that's easy. It's also slow and takes a lot of land.
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Old 03-26-2020, 11:56 AM
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Urea production is practical for making urea. It isn't practical for sequestering carbon.
The point is that their is a profitable use for sequestered carbon that can at least partially offset the financial and energy costs of sequestering the carbon from a point-of-emission source.

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eschereal, if you're referring to growing plants, sure, that's easy. It's also slow and takes a lot of land.
Actually, carbon absorption by plants is quite efficient. The Empress tree is highly efficient, capturing 103 tons or carbon per acre-year, and best of all, doesn’t require any supply of power except from the Sun, and produces a very useful form of sequestered carbon. Molecular biologists and research botanists are working on varietals with even higher capture rates. Yes, this does take land but that just means we need to put more effort on stopping the needless clearcutting of land for low yield agriculture and to start replanting forests across the Americas and Europe that were decimated prior to the Industrial Era. And cultivating carbon-consuming plants and trees is something we can do right now at very small cost while research on other methods of carbon capture and reducing carbon emissions continues apace.

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Old 03-26-2020, 11:59 AM
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Hey look we can sit and talk about CO2 capture methods, global dimming or nuclear energy till there’s another Ice age, but the real elephant in the room is not technical knowhow but Geopolitical economics and politics.

China is not gonna give up on coal because it’s produced domestically. Russia and Saudi Arabia are going to fight over oil prices and who knows where it will take oil prices. Right now the Natural Gas industry is taking a big hit because of low demand and future looks bleak.

Big Investments in large projects (usually big CO2 emitters) require long term predictability (technical , economic and geo political). The more the uncertainty, the more the investments will go towards “traditional conservative methods” which are usually not the best option. Look at a good logical country like Japan and see how they decided to go back to old nuclear even though new options were available. Look at Germany and see how they decided to go to coal.

And for the record, Dakota gasification used to make natural gas from coal and send most of the produced CO2 to Canada to be used in Oil wells for EOR. This was a large scale operation much in the scale of Desired CO2 capture scales. But now with cheap natural gas, their whole financial model has collapsed with no chance of recovery.

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Old 03-26-2020, 12:27 PM
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Hey look we can sit and talk about CO2 capture methods, global dimming or nuclear energy till there’s another Ice age, but the real elephant in the room is not technical knowhow but Geopolitical economics and politics.
All true, and is the fundamental reason that we won’t do anything about climate change, because nobody wants to be in the circle by themselves while everybody else is dancing their way to destruction.

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Old 03-26-2020, 12:34 PM
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eschereal, if you're referring to growing plants, sure, that's easy. It's also slow and takes a lot of land.
Well, there really is a lot of land, and greening it up does not irreversibly consume that land, or even make it non-useful. And it is not slow, inasmuch as young plants really are pretty good at sucking up the CO2 – we do not have to wait a long time if we plant a lot of plants, which can later be selectively culled.

There are other issues as well. Deforestation of the Amazon Basin is affecting weather patterns in that region, such that most of Brazil may be destined to become Sahara West if the process is not curtailed, if it is not already too late.

Of course, the downside to aggressive bio-carbon capture of this type is the waste product: oxygen. That stuff is dangerous, corrosive and tends to cause certain catastrophic chemical reactions. We have just about exactly the right amount in the atmosphere; too much more could be a bad thing. Also, it is a problem for some 5G signals.
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Old 03-26-2020, 12:39 PM
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Of course, the downside to aggressive bio-carbon capture of this type is the waste product: oxygen. That stuff is dangerous, corrosive and tends to cause certain catastrophic chemical reactions. We have just about exactly the right amount in the atmosphere; too much more could be a bad thing.
I bet the anaerobic microbes at the time wished they had taken quicker action on the global oxidation problem before it consumed all of their life-giving carbon dioxide and methane.

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Old 03-26-2020, 12:51 PM
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There are other issues as well. Deforestation of the Amazon Basin is affecting weather patterns in that region, such that most of Brazil may be destined to become Sahara West if the process is not curtailed, if it is not already too late.
Again, this is the narrow hat of environmental focus without taking in the whole picture.

Brazil, Papua New Guinea, Costa Rica, etc etc have all approached the international community promising to not cut down forests if a fair amount of economic value is given by the industrialized nations. But they got pretty much Nada.

The broader global socio economic issues in the world need to be addressed if we want to win in the climate change challenge. It has to be a global community with global awareness and dedication to solve a global problem.
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Old 03-26-2020, 01:09 PM
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OK, Empress trees can sequester 100 tons per acre per year. The US currently produces about 5 billion tons of carbon dioxide per year. That means we'd need 50 million acres of empress trees to sequester all of that. That's half the area of California. And then we'd need to harvest all of that wood when the trees reached peak growth, and do something with all of it (dump it in landfills, if nothing else), and replant all of it.
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Old 03-26-2020, 01:13 PM
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And harvest and plant it in a carbon-neutral way and make sure none of it decayed. And then hope the soil will sustain a planting every decade or else find another 50 million acres to use the next decade.
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Old 03-26-2020, 01:40 PM
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I bet the anaerobic microbes at the time wished they had taken quicker action on the global oxidation problem before it consumed all of their life-giving carbon dioxide and methane.

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Their leaders had no spine but ours d... NM
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Old 03-26-2020, 01:48 PM
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I didn’t say that planting trees would be a complete solution to offset current emissions; what I said is that it is something we can do right now to mitigate atmospheric carbon at minimal cost and energy expenditure, and frankly, it scales up to however much land cis available to be planted. As far as finding something to do with the product, wood is nature’s natural composite material with a strength-to-weight ratio exceeding that of alloy steels, natural flexibility and vibration damping properties, solid or ply-laminated wood is quite resilient if treated properly compared to many common building materials like gypsum sheetrock or medium density fiberboard, and of course wood has a negative carbon footprint compared to steel, aluminum, or cement used in concrete construction. It can also be used as a suitable substitute in many applications where plastics are used today, albeit not as cheaply as injection molding.

Apropos of nothing, Ron Swanson on wood.

“Salt water will warp the wood...so keep your tears in your eyes where they belong.”

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Last edited by Stranger On A Train; 03-26-2020 at 01:50 PM.
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Old 03-26-2020, 02:04 PM
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Back on topic, scr4 brought up the inefficiency of the refining and delivery process for oil. A quick look around suggests there's about a 15% energy expenditure in the refining process, whether through the use of electricity or burning of some of the input oil to run the process. This guy did a pretty extensive analysis that was too long for me to dig into https://www.linkedin.com/pulse/so-ex...n-paul-martin/

Either way, there's a definite cost to the refining process, and my understanding is that dirtier tar sands and some of the fracked crudes can require nearly as much energy to refine as you get out of them. The extraction and transport costs for oil and gasoline are apparently very low due to pipelines and efficient pumping and transport. For something like coal you'd have higher extraction energy, but still rather low transport energy since most of it goes by barge or rail, with no refining necessary.

So really you have to look farther down (up?) the supply chain to make meaningful comparisons. It's not just about the efficiency of the plant/engine, but the efficiency of the fuel itself. Otherwise we'd all be heating our homes with electric resistance baseboards because they're 100% efficient, hooray!
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Old 03-26-2020, 05:20 PM
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The other thing with making sequestration (by any method) practical is looking at the costs compared to the alternatives. I can imagine a fossil-fuel power plant that owns the appropriate amount of land, and plants trees to offset its carbon footprint. Obviously, power from that plant would cost more than from a non-offset plant of the same type. That in itself might not be a problem: You can find people willing to pay a premium for carbon-neutral power. But how much would it cost compared to the same capacity worth of, say, windmills and storage batteries? If the windmills plus batteries are cheaper than the fossil plant plus tree farm, and serve the same needs, then why build the fossil plant plus tree farm at all? And if the fossil plant plus tree farm is sufficiently expensive that there's no reason to build it, then it can't really be said to be practical.
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Old 03-27-2020, 04:09 AM
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So is it fair to say that if the thermal efficiency of the worst producer of electricity on the grid is above ~40% the EV is on par with an efficient ICE?
(That makes EVs a net benefit in most western nations with moderately efficient power plants.

But I still doubt the map in the article from Arstechnica.

And I want to point out that European nations would be better of subsidizing export of clean(er) power to countries with older plants than subsidizing EVs.
(banning more inefficient cars would be even better bang for our environmental buck)
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Old 03-27-2020, 08:38 AM
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It's not the efficiency of the least-efficient plant that matters. It's the efficiency of the marginal plant. These may or may not be the same thing. One can imagine a nation that still keeps an old, inefficient plant on their grid because it would cost even more to decommission it, but which would use plants of a more modern, efficient design if it became necessary to add more capacity.
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Old 03-27-2020, 03:28 PM
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It's not the efficiency of the least-efficient plant that matters. It's the efficiency of the marginal plant. These may or may not be the same thing. One can imagine a nation that still keeps an old, inefficient plant on their grid because it would cost even more to decommission it, but which would use plants of a more modern, efficient design if it became necessary to add more capacity.
I never looked at it from that angle. Thanks!
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