(Nearly) Unlimited Energy?
This weekend, while in Minneapolis, I started reading Jerry Pournelle's 1979 book, A Step Farther Out. I was reading it on my Kindle, natch.
In the first chapter, Jerry advocates a form of energy production known as the Ocean Thermal System (OTS).
It is an Earth-based solar power system, and the concept is simple enough. All over the Earth the sun shines onto the seas, warming them. In many places--particularly in the Tropics--the warm water lies above very cold depths. The temperature difference is in the order of 50° F, which corresponds to the rather respectable water-pressure of 90 feet. Most hydro-electric systems do not have a 90 foot pressure head.
The system works simply enough. A working fluid-such as ammonia--which boils at a low temperature is heated and boiled by the warm water on the surface. The vapor goes through a turbine; on the low side the working fluid is cooled by water drawn up from the bottom. The system is a conventional one; there are engineering problems with corrosion and the like, but no breakthroughs are needed, only some developmental work
The pollutants associated with the Ocean Thermal System (OTS) are interesting: the most significant is fish. The deep oceans are deserts, because all the nutrients fall to the bottom where there is no sunlight; while at the top there's plenty of sun but no phosphorus and other vital elements. Thus most ocean life grows in shallow water or in areas of upwelling, where the cold nutrient-rich bottom water comes to the top.
More than half the fish caught in the world are caught in regions of natural upwelling, such as off the coasts of Ecuador and Peru.
The OTS system produces artificial upwelling; the result will be increased plankton blooms, more plant growth, and correspondingly large increases in fish available for man's dinner table. The other major pollutant is fresh water, which is unlikely to harm anything and may be useful.
Well, that sounded impressive enough. This book was written in 1979. Why haven't had I heard more about OTS? Then, this morning, I did hear more about OTS. The New York Times published an article about it. The Times' article offers a brief overview of the technology while also talking about how expensive it could be to use.
Skeptics say that the technology is highly inefficient because it requires large amounts of energy to pump the cold water through the system.
Patricia Tummons, who edits the newsletter Environment Hawaii, said a major question about the technology was "just how economical it can be."
Robert Varley, who is helping to lead Lockheed's efforts, estimated that just 3.5 percent of the potential energy from the warm water pumped might actually be used. "In reality that doesn't matter -- the fuel is free," he said.
This is something I'll be keeping an eye on.