The conversion of energy from heat to free energy (usually torque or electricity) is one of the most fundamental, far reaching topics both in basic science and in global energy economics. The challenge itself is very old, but new opportunities have emerged for R&D to make radical improvements in the attainable efficiencies for the two main approaches to thermal conversion – heat engines, which convert temperature differences to torque, and thermoelectrics, electrical devices which convert it directly to electricity. If we can take advantage of these unmet fundamental opportunities, we can enable a whole series of fundamental transformations in the world energy system, of immediate benefit to energy security and sustainability.
The most near term and urgent opportunity concerns small-scale heat
engines, which can be used to produce torque (or, with minor extension,
electricity). Down at the level of 200 kilowatts or below, the world
mainly depends today on internal combustion engines, which really convert
specific fuels (gasoline or diesel) to torque. From basic thermodynamics, it
has long been known that “external combustion” or
This past year, two new events have occurred to reopen this door.
First, in Business Week (September
12, 2005) it was announced that a new company, Stirling Energy Systems (SES)
signed a contract with Southern California Edison (SCE) to build a 500 megawatt
solar farm in Southern California, using reflectors to focus light/heat onto a
Stirling engine, to make electricity. SCE stated that the agreed price was
“well under the 11.3 cents per kwh that we pay today for daytime peak power.”
SES certainly had access to a working, affordable
Second, the original inventor himself submitted (with a group at Kettering and Oak Ridge) have put together a proposal, to try to prove that it is possible to design a credible third-generation Stirling engine, doubling the efficiency (electricity output) without measurably increasing the cost, say, of a solar farm. The benefit of doubling the efficiency is that it cuts the cost of solar electricity in half, allows solar to beat natural gas in the market for peaking power, and revolutionizes the world energy market. Whatever the risks and uniqueness of this effort, the potential benefits to humanity and national security are a matter of life or death.
In an ideal world, mechanisms would be found not only to fund their technical proposal, but also to allow universities such as Kettering to compete for a new university-based center in external combustion technology designed to fill the critical hole here – the development of a new talent base of people creative and knowledgeable enough to follow up on the potential of the 40% 40 kilowatt engine and to push ahead to 55% in the future.
If such a base can be developed, it would enable further research and transformations, and new partnerships, such as: (1) combining the new engine with new reflector designs, new technologies combining optimal (ADP) control and power electronics to hook these systems up more efficiently and cheaply to power grids, aimed at developing a credible option for a 100 megawatt minimum-cost solar farm demonstration – the basic R&D needed as a prerequisite before someone else actually pays for the demonstration; (2) developing variations for use in highway vehicles, where efficiency would be comparable to fuel cells but fuel flexibility would be automatic and production could be ramped up quickly in existing US engine factories; (3) developing new processes to convert CO2 or other gas streams in “Clean Coal” plants into methanol fuel, by using an input of solar energy; (4) developing cheaper systems for remote power and remote power use in poor remote areas of the earth, using local heat sources from biomass or other sources.
minimum cost solar
conversion is perhaps similar to what