Thursday, May 1, 2008

Introduction to Thermopower

First, we want to make it clear that this is not a "perpetual motion machine." For some reason, perhaps the result of an incredibly poor science education system in the US, some individuals think that conversion of heat to electricity is a violation of the Laws of Thermodynamics. It is not. The effect is called the Thermoelectric Effect and it has been known to science for almost two centuries. Thermoelectric Power, or thermopower for short, refers to a class of phenomena in which a temperature difference creates an electric potential. Thermoelectricity is used in your home in some appliances, for instance. "Seebeck effect" is the official name for the effect, but thermopower is a more accessible term and one we will use.

Why We Don't Generate Much Electricity from Thermopower Today

The problem with traditional thermopower devices which convert heat energy into electricity is that the conversion efficiency is very poor, typically in the 2% range. This means that if 100 units of heat energy go into the device, only 2 units of electricity are produced. This is okay for some uses, for example if you want to turn on a valve on a gas water heater with a pilot flame. But, if you want to generate substantial electricity from a reasonable temperature differential, it's not practical at all. Many research projects, including a huge project in the Soviet Union in the 'Eighties, have tried to increase the conversion efficiency for thermopower generators (and, they have succeeded to a limited degree). And, of course, we have thermopower generators on board mankind's most distant spacecraft (Pioneer and Voyager spacecraft) to thank for continuing to send us science data from well beyond our own solar system. Yet, even those generators can only produce a few watts of power. Still, that's far more than any batteries could have done over many decades of flight (they would have gone dead many years ago).

The real sticking point is that of inefficiency of the generator. A thermopower generator's inefficiency comes about because the temperature gradient within the generator must be maintained to continue to generate electricity. But, heat tends to flow to the cool side of the generator, reducing the temperature differential. Traditional thermopower devices generate a peak in electrical output when they are first turned on, but as the temperature differential falls, power output drops substantially. Some research projects report that by using expensive materials which conduct electricity well but act as heat insulators, efficiencies of the thermopower generator have been increased up to the 10% level. That's close to being competitive with traditional electric generators. Of course, the "fuel" used to generate electricity is plain old heat, something many people have an overabundance of, especially if they live in Death Valley, California, the Australian Outback, or Texas. At least, no one can compete with "free" in terms of fuel cost!

Maintaining That Temperature Differential Is The Key

The key breakthrough for the our project has been to create a generator which maximizes production of electricity while maintaining the temperature differential at an efficient level within the generator. Now, this is where the "know-it-alls" start to complain about "perpetual motion machines." But, they are wrong because the generator is not a closed system — it must continually draw in heat energy from outside the generator to continue generating electricity. In contrast, a "perpetual motion machine" would violate thermodynamic laws because it would be a closed system.

Is it perfectly efficient (100%)? No, it is not. But, it is a quantum leap in efficiency compared to all other known attempts at thermopower generators. That's what makes it a true breakthrough — it makes clean energy available at a cheap price. And, the implications of that are astounding when you think about it.

A Fundamental Change In The Way Electricity Is Generated Is Needed

Traditionally, electric generators have been powered by organic fuels, such as natural gas or oil. Those fuels must be obtained at a cost which is continually rising. And, the waste products of burning those organics has been pollution of our environment. Radioactive decay has been used to generate electricity (nuclear fission reactors), but has problems associated with mining of the fuel and disposal of waste products, not to mention the very real problem of nuclear weapons proliferation to groups inimical to peace. Fusion reactors may come online in the future, but to demonstrate how long that might be, we note that we attended a Fusion Power Symposium at the University of Texas at Austin in 1963 and the most brilliant fusion physicists at the conference believed we would have fusion reactors running in the 'Nineties. The most optimistic estimate today is the 'Thirties for a working prototype fusion power plant. Fusion also has waste problems due to the fact that the reactor vessel is bombarded by highly energetic particles over a period of time, becoming radioactive itself.

Clearly, the problems with both organic and nuclear power plants are severe. Yet, those kinds of generators continue to be built and will bring us more pollution problems from rising demand from a growing and power-hungry population. And, the price of electricity continues to rise as well.

An alternative which generates cheap electricity without producing pollution is sorely needed.

The benefits of harnessing wind, wave and solar power are obvious: these are naturally-occuring and somewhat renewable and non-polluting resources. Unfortunately, they are rather limited in their ability to scale up to the needs of modern civilization. Although much more could be done with renewable resources than is being done today, resistance even from environmental groups to the use of wind turbines suggests that expansion of these sources of electricity will be very difficult in the kind of quantities which will be needed in the future to replace conventional generators.

An Ideal Way To Generate Electricity From Abundant Heat Energy

The foremost quality of this breakthrough is that it represents a fundamental change in the way practical amounts of electricity can be generated.

A generator which works directly from heat input is an ideal solution to the problem. Heat is available everywhere. Most of the time, it's excess heat which people worry about, such as Global Warming. If there is a problem with Global Warming, we have an answer (convert the excess heat to radio waves and beam them into space). That's if Global Warming is a real problem.

Is the Outback too hot and dry to live in and grow crops? Use that excess heat to drive our generators to desalinate sea water, pump that fresh water into the Outback and irrigate crops with it. The climate will cool due to the added greenery and it will become an ideal place for people to live (especially since some of the heat can be converted into electricity for home and commercial use). We'll bet real estate prices in the Outback are a steal right now, just like California real estate was a couple of centuries ago.


How We Got Into This Mess

The price of oil reflects the mass delusion that the future will look exactly like the past. Just because we have foolishly burned oil to produce power for hundreds of years and thus gotten our civilization into a bad situation does not mean that the future will not bring a radical change in the way we produce power. The 'Seventies offer a good example of opportunities lost. Exploding oil prices are a signal to the market that new ideas are required. The last time we had a similar situation in the 'Seventies, the politicians in Washington destroyed innovation in alternative energy by imposing heavy taxes on companies engaged in finding and producing energy products — the so-called "Windfall Profits Tax." The subsequent collapse in the energy price structure (oil was selling for $10/barrel in 1998) eliminated alternative energy and made this current bubble possible. We missed our best opportunity to avoid the current pollution and ravenously high prices (and, weakness in the US Dollar, we might add). Such is the short-sightedness of both the Congress and the American people. Now that the price of oil is undoing all of the interest-rate stimulus provided by the Fed, it has created the perfect storm for the economy.

2 comments:

x96493 said...

I've been following this discussion on thermopower ever since it was brought up on TTC earlier this year. I'm a nuclear engineer grad student and work with thermoelectric heaters every day in my research. Granted I use them to heat and cool and not generate electricity, but I still have a fairly good understanding of how they work.

Here's what I don't understand. To generate electricity, there needs to be a temperature gradient across the thermoelectric. Basically one side of the thermoelectric needs to be hotter than the other. I understand where you are getting the heat from, but I don't understand where you are getting the "coolness" from. If I throw a bunch of thermoelectric generators onto the roof of my parents' house in Arizona, I would think that both sides of the thermoelectric would just gradually get hot with very little difference in temperature (if any) between the two sides of the thermoelectric - hence very little (if any) electricity generated.

So is this breakthrough your group has achieved based on new materials that can produce large amounts of electricity with very small temperature gradient? Or is it more of an engineering and/or installation breakthrough?

I was really interested in this when the subject was first brought up on TTC and even asked for an investor information packet (this was before your group starting issuing normal stock). Unfortunately, there wasn't any technical information and the questions I posed above weren't satisfied.

I know you can't give away any proprietary information, but to the best of your ability, could you address my questions above? I just don't see how this is possible without either a materials or engineering breakthrough. Thanks for your time.

Bob Carver said...

The exact details at this time are proprietary, but I can give a rough outline of the process.

The problem boils down to a tortoise and hare problem. Electricity moves at the speed of light, but heat moves much slower, so it's the key to creating a stable gradient in the generator. What we do is to periodically switch the source and sink internally within the device. This causes the gradient to remain stable. Since it's a reversible process we're using, the losses are insignificant (just resistance losses in the circuit, mainly).