What sustainable technologies exist or nearly exist?

What are some examples of sustainable energy producing technologies? I’ve found that there is a myth that environmentally sustainable solutions are not economically viable. However, I have found this to be false, because the definition of sustainability is dependent upon a technology’s efficiency, therefore a truely sustainable tech would actually be more economically feasible.

I’ll give the example of Peak Oil . The basic concept as I understand it is that we will eventually reach a point where the energy required to aquire a barrel of oil will exceed the energy output of a barrel of oil, making the aquisition of oil undesirable.

So for a tech to be sustainable it needs to require less energy output to aquire it than it produces.

So I’m going to start us off with Biodiesel and Solar Paint. Now I won’t say much about Solar Paint as I can’t really find any examples of it being available to the public just yet, but it’s a neat idea that I feel is about to come to fruition as I found a couple links referring to people working on making it possible. However, in the case of biodiesel, I have heard people talk about it’s economic value, and the fact that it generally is more expensive than petrodiesel. This is something of a misnomer, as most biodiesel that is currently in production is produced from soybean oil which isn’t all that great for cooking. The soybean industry has been one of the main pushers of biodiesel. However, the problem with soybean oil is that it’s a very expensive way to produce biodiesel. Reclaimed frier grease from restaurants is a much cheaper way to produce biodiesel, as it is a waste product that has already been produced for another purpose and they are not producing it purely for this purpose. So if biodiesel were to be made from reclaimed vegetable grease, it would actually be cheaper than petrodiesel. The first diesel engine ran on Hemp and Linseed oil.

So what are some other sustainable energy technologies that aren’t really in use? I’ve been wondering specifically about ways to reclaim kinetic energy from the motion of the Earth, ourselves etc… Taking the self-winding watch concept much further. I had an idea for a boat that had a whole bunch of mercury switches inside it to reclaim energy from the tides.

I’ve been really interested in this for the past few weeks because I just took a trip on my friend’s veggie bus to the Rainbow Gathering. The bus itself has filters inside of it that filter the vegetable oil to get rid of particulate matter, and then has a line running from the radiator into the fuel tank to heat the oil in order to thin it so that a diesel engine can compress it as it would diesel fuel. It has a smaller diesel tank that is used to get it started. The bus also has a solar panel and battery system that can run a sound system for a party for a few hours.

So I’m interested in other such sustainable techs that I might not know about. I read the article in Wired about the guy reclaiming it from the bottom of the ocean, that was interesting in case any of you haven’t read it. So it seems to me like people are really on this tip right about now.


We Loooooooove You!

lol, damn hippies can’t ever answer a straight forward question. I don’t want a hug, I want answers! :stuck_out_tongue:

Well, nothing is sustainable. The sun is going to expand past our orbit eventually so all our earth-related tech is going to have to end. For relatively LARGE values of sutainable, we have fission. For extremely LARGE values of sustainable we surely will eventually have fusion on earth/orbit. For utterly LARGE values of sustainable, we might be able to develop good solar tech.

Also, you have to account that not every environmental policy that increases sustainability makes sense, is good, or even useful. Take this for example: We exterminate 99.99% of population. That’ll certainly end the energy crisis, since now there’s enough oil again. However, does that make good energy policy? …actually let me think about that… :wink:

Okay for a somewhat serious answer. (and please - other Dopers know a LOT more about this than I do so feel free to add to and/or correct this posting).

Solar Power. The Earth receives 1.5 horsepower of sunlight per square yard. That’s roughly 1,120 watts per square yard. Solar cells operate at about 10% efficiency so you would get a yield of 112 watts for a 1 square yard solar cell. Solar cells are expensive, and have 2 other drawbacks. 1) cloudy days 2) nighttime.

Tidal Power - This is one of those “power of the Earth” technologies you mentioned. This is limited to areas that have huge tidal ranges. It also has other limitations - shipping traffic; fish have to be able to travel through the tidal generators somehow.

Ocean Wave Power - No doubt I got the name of this wrong but this is similar to what you mentioned about the boat with the mercury switches. I believe the most recent ideas are to use “floats” that can convert the mechanical energy of waves into electrical power. (I believe these floats are called “ducks”.)
Disadvantages are the fact that these have to be positioned in the ocean making repair and maintenance difficult especially during a storm.

Wind Power This does not deliver the whopping amount of energy that some people think it does. Winds are not constant and the generators look ugly.

I have typed this pretty quickly with very little actual data about what each technology can generate. Also, I have failed to mention other enegy technologies (fission, fusion, geothermal, etc). So, let’s see what other Dopers have to say.

Tidal Power and Ocean Wave Power both very expensive to impliment and yield not enought to meet demand.
Solar Power has lots of research and little real progress evidenced.
Wind Power has a number of wind farms in operation. Current output power cost is higher that conventional. Will have to be improved to gain public acceptance on a large scale.
Solar Paint ?? Whatcha hittin on? Opium? It’s a ‘pipe’ dream.

Dr. Thomas Bearden has the overall solutions already for implementation at:

Energy Crisis Solutions

The Final Secret of Free Energy

I thought this thread would have lots of postings by now.
Anyway, a quick search on the Internet about wind power yielded the following information.
A 1 megawatt wind powered generator costs roughly one million dollars, yielding 1 kilowatt per $1,000. Not surprisingly, the smaller the generator the more expensive it is in terms of dollars per kilowatt.

Well by the OPs own standard of sustainable (it needs to require less energy output to aquire it than it produces) then coal and oil are the obvious sustainable technologies. After all if we weren’t getting more energy out of oil than we are using we wouldn’t be getting oil.

I’m assuming that there is an implicit timeframe in there that he has left totally unstated. The problem is that it is all totally dependent on how you want to define a sustainable timeframe, and the OP hasn’t done that. Until that is done it’s impossible to answer.

As an example, all the suggestions made so far rely on the use of plastic coated wiring and the use of metals. Now plastics come from mineral oil and metals come from mines. Any technology that makes use of those things in anything but trivial quantities won’t be sustainable because those resources will eventually be depleted. It may take thousands or millions of years, but those technologies aren’t infinitely sustainable as they stand.

This is always the biggest problem with any sustainability question. There’s no agreed upon standard for a sustainable timeframe. To the best of my knowledge no human technology beyond the Neolithic has ever been truly sustainable. And of course plenty of Neolithic technology was unsustainable as well.

It very hard for me to see how any energy production system, which seems to be what the Op wants, could ever be infinitely sustainable at anything near current technology levels. Eventually the metals will all have been dispersed or washed into the oceans so forth and then we will have to use a hell of a lot of energy to extract them and refine them all over again or else use very low quality ores, which have the same problems.

Those Thomas Bearden sites seem to be pseudo-scientific.
For one thing, he was forced to admit that his PhD is based on “life experience”.
He is not the first to propose a new energy source. Search the Internet for people such as John W Keely (from the 19th century) and Joseph Newman, who I believe is still getting money sent to him.


wolf_meister, PhD in Astrophysics
DeVry Institute

The problem with the wind-powered generators is that in order to get the best wind, you need to place them along ridgelines, which is where all those golden eagles and hawks and things like that soar along while searching for prey. A few too many protected birds fly into a windmill, and the animal rights’ activists are getting a mite upset.

There was a thread a while back with a link to a power generating proposal which was basically a vertical wind tunnel: you make a tower about a mile tall and a quarter mile wide, have a big circle around the tower with clear roofing, paint the floor black and let the heated air into the tower. It rises, and as it rises it drives a turbine, which generates electricity.

The problem with the system is that they haven’t been able to nail down exactly how much it would cost to make in terms of money and energy (it’s a concrete chimney a mile tall…), and how much energy it would produce, and whether or not it would ever actually pay for itself…

In fact, the OP makes a very common mistake in implicitly claiming all forms of energy are equal. It is very likely that we will continue to bring oil out of the ground long after the energy it takes to raise the oil exceeds the amount of energy we can get from burning the oil.

Oil is compact, transportable, and reliable. I could envision a setting where drill rigs are solar and wind powered, with the intermittent nature of each of those power sources unimportant as the oil flow would not need to be continuous. Or where waste natural gas is used to power oil equipment. Either of those settings could spend far more energy than they retrieve and yet still be economically viable, based on the price of oil.

This is based on bad initial sitings. Power companies that work with bird experts on siting windmills have drastically reduced bird kill just by moving a few hundred feet left or right to move out of established flying patterns. This comes at no loss of wind power. (The preceding was from a Power Magazine article a couple years ago. I have no web cite.)

Wind power, on a $/kWhr basis of energy produced, is cheaper than coal power in many locations. The biggest impediment to getting more wind power is that to maintain a stable energy network, power companies have to have a certain amount of reliable power and wind is not reliable so it does not factor into the needed reserve. So the power company has to not only build the wind generator, it also has to build a coal plant to mainain it’s reserve requirement for when the wind is not blowing. And wind is not THAT much cheaper than coal to justify building both. So they only build the reliable one.

I’m a little curious, that 1 megawatt power generator… How often does it produce 1 megawatt? Is this every day, week,or year? Depending on where the generators are placed, this could change the kilowatt/dollar ratio. Also what is the life expectancy for a wind generator? I’m guessing that this would reduce the $1,000 a kilowatt price quite a bit.

That’s peak solar energy, with the sun directly overhead, on a clear day, at high altitude. Taking into account atmospheric scattering, clouds, oblique light most of the time, seasons and nighttime you get an average of about 100W per square metre. The best voltaic cells are more than 20% efficient, but as you say they are expensive. I have heard it alledged that solar cells don’t produce enough energy over their lifetime to cover the energy used in their manufacture - no idea if that’s true.

For large scale solar power generation, you wouldn’t use voltaic cells. Solar concentrators such as tracking mirrors (heliostats) work by focusing sunlight to up the temperature and using heat engines. The benefit is the cost per area is much smaller for tracking mirrors than for solar cells. Efficiencies are similar. Other designs include the solar chimney, which basically involves painting large areas of land black, suspending clear plasic sheet above them and putting a huge chimney in the centre. The solar convection draught is used to turn a turbine. Efficiency is pitiful but the low cost per square mile might make it worth doing if you have a lot of desert to play with.

Space-based solar power has a lot of potential in theory. Whenever the concept makes the news, some dimwitted artist produces a picture of something like a square mile of solar cells in space supported by a scaffold, something we probably couldn’t build in fifty years. Whereas the real beauty of space-based solar is that most of the collector is mirror, and the mirror doesn’t have to support its own weight or worry about the wind. A square mile of wispy aluminised mylar sheet could weigh less than a tonne. The generator unit would be a heat engine again. Building a radiator for the cold side of the heat engine would probably be more difficult than building the collector.

I’ve seen designs for tidal power that avoid these problems. One involved huge floating barges anchored to the sea bed. Power was extracted as the tide lifted the barges and the anchor cables unwound with great force, geared up to spin generators. Back-of-the-envelope: for a 100,000 tonne barge and 0.6m tidal range (open ocean) twice per day, you could generate the equivalent of a whopping 13.6 kW continuously! Another one I liked was east-west tidal tunnels running clean through the UK or Panama…

Somewhat more practical may be the concept of putting tidal current turbines in shallow water, which is at least as sensible as sticking wind turbines on every hill you can find.

Maybe these problems can be designed around. A modern float system is Pelamis - details here.


There’s also a fair bit of interest in air turbine systems, driven by oscillating columns of water from incoming waves. These units tend to be shore-based and theoretically can be very robust.

I don’t happen to think the generators look ugly, but the thousands required to generate a substantial fraction of our energy needs is pushing it. I’d like a few hills unadorned, thanks.

There was a New Scientist article a while back about extracting energy from high-altitude wind using tethered, angled turbines like kites. Nice bit of lateral thinking, if rather impractical!

One of my favourites that doesn’t get enough press in my opinion is OTEC, which was discussed in a lot of detail in another thread:

OTEC is basically very low efficiency solar power. Its advantage is that the sea acts as your collector, so a tropical region gives you several thousand square miles of effective collector area without having to build vast fields of collector mirrors or lay plastic sheet out everywhere. It also has been demonstrated to work on a small scale.

Wired Magazine seems to think its readership loves stories about sustainable energy:

… etc.

How does the energy get to the ground?

A little tangent off of the idea of large-area things in space. I’ve wondered how Venus would be if we could somehow erect a very large (very large!) sheet of opaque material such that the entire planet is in shadow. Would the planet eventually cool enough to be terraformed? But then I start thinking about solar winds. Wouldn’t they blow such a large structure away?

And what about the mile-square generator? Wouldn’t the solar winds blow that away?

Wind power. I used to live where there were a lot of wind turbines. I didn’t find them ugly at all. I liked the contrast between the rugged desert and the techy-looking turbines. Winds were very reliable there, but sometimes they were too strong. I’ve heard the complaints that too many birds will be killed if we step up the production of wind-produced energy. Seems to me that some birds will learn not to run into them, and only the stupid birds would be killed. Soon we could have super-intelligent raptors!

Solar power. I’d visit my dad in Daggett in the summers when a solar plant was being built nearby. A large array of mirrors heated a liquid-filled drum that sat atop a tower. One thing about the desert: it’s sunny more often than not.

Biodiesel. I’ve asked before on these boards, and the answer I got was that if we switched to 100% biodiesel we wouldn’t have enough crops to feed us. I hadn’t thought about waste oil, which is popular with many people. Since it’s already been processed, it makes sense to recycle it. But how many users can be supported by a single restaurant?

It seems to me that each group that supports a certain type of energy tends to belittle other sources. For example, an Oil Man will say that petrolium packs the most punch per unit, can be taken to where it’s needed, etc. He might say that solar power or wind power is not as efficient and can’t be easily transported, so there’s no sense it building such power plants. I think that it doesn’t really matter if one source is more or less efficient than another. I think that we need not only to look at energy efficiency, but also at the environment. Solar, for example, pollutes less than petroleum. Some places, such as deserts, are suited for solar power plants and wind-turbine farms. Other places are not. Some places can use geothermal energy, and some places can’t. Why not build energy plants that are suited to their locations? When the thechnologies become more efficient, the infrastructure will already be there.

Oh, was that the first clue? :wink:

Here’s the thing that gets me about these type of claims; in the midst of rambling on about how outmoded and incorrect “classical” EM theory is, he breaks off with

So, one minute we’re offering up a solution to the world’s energy needs via “overunity” power, and the next we’re curing cancer. What’s next? An effective treatment for halitosis based upon magnetic monopoles?

My favorite, though, is still Randy Mills BlackLight Power, and his Classical Quantum Dynamics theory that explains everything from cold fusion to dandruff.

Sustainable energy technologies; wind and geothermal are good off-grid, or limited grid technologies but are limited to locations where those sources are readily available. You can’t plant a turbine anywhere and expect to get steady wind. (Also, windplants have a large footprint and are fairly loud.) Wave action has some potential, but there are serious concerns about damaging fragile ocean habitats and the maintainence on such systems is nightmare-inducing. (San Francisco has considered mounting water turbines to the bottom of the Bay and using the inflow and outflow to generate a significant amount of energy. It’s not a bad concept, but when you consider the difficulty of permanently mounting anything to the sandy, silty bay floor, then trying to maintain any equipment, plus the possible environmental impact it becomes a lot less appealing.)

Solar is the best answer given the current state of the art, but photovoltaic system have signficant limitations and are best suited to minimal, off-grid situations. Heat engines, like a Stirling cycle piston engine, are better suited to large installations but will require a large footprint and significant maintainance; it’s not clear how competative this could be with a coal- or gas-fired plant.

Fission is the best “sustainable” technology available right now, and with proper management waste could be minimized and handled safely, but a political nightmare; even with the current generation of safe pebble bed reactors the public perception is one of extreme danger. (Never mind that a coal fired plant outputs an order of magnitude more radiation than a properly maintained nuclear reactor.)

Nuclear fusion is still decades out; there is no reliable estimate on when sustainable fusion reactions might be possible.

Orbiting solar satellites and O’Neill-type colonies are a nice idea, but as someone else pointed out, you have to transmit the energy to ground somehow. During the 'Eighties there was a big rage for microwave transmission (essentially, an extremely powerful microwave-range laser), but this has enormous technical questions, not to mention the side effects of pumping gigawatts of power through the atmosphere. A better solution is to process the raw energy into some kind of potential chemical energy, like clean natural gas or methonal, but that requires raw materials to be hauled up from Earth or somehow collected in space; not a feasable plan given current capabilities.

Ultimately, we should be looking for more efficient ways of using and transmitting energy along with supplementing fossil fuels with more renewable forms, but we aren’t going to eliminate the use of coal, natural gas, and petroleum any time in the foreseeable future.


I hope this is a joke . . .

I like nuclear power. I don’t think the plan to store the waste in Nevada is particularly good, from what I’ve read about the area being seismincally active and the risk of radiation getting into the aquifer. Europeans seem to use nuclear power more than we do. How do they handle the waste?