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Renewable Energy

“Alternative renewable fuels are at present far from competitive with fossil fuels in cost and production capacity. Without viable options for supplying double or triple today’s energy use, the world’s economic, technological, and political horizons will be severely limited.” (DOE Solar Energy Report)

Since all forms of energy can be converted to electricity, within certain limits, green energy sources can be very important. Their potential in most cases is quite limited, however.

Wind is kinetic energy that can be converted to electricity by driving a traditional electromagnetic generator. It has both advantages and drawbacks, the latter including visual appearance, varying reliability, and cost. Moreover, while wind electric will increase substantially from its present base, the amount of energy that can be harvested from wind is much less than world demand.

Water power from hydroelectric plants has been largely exploited in OECD nations, where there are few plans to install new major hydroelectric projects in the future. More mid- to large-scale hydroelectric projects will likely be built in developing non-OECD nations in Asia and Central and South America, though environmental and other reasons have slowed hydro development in recent years. (DOE International Energy Outlook) As a fraction of the world’s overall power consumption, all forms of hydro generation will actually decrease in the future. “The United Nations estimates that the remaining global, practically exploitable hydroelectric resource is less than 0.5 TW. The cumulative energy in all the tides and ocean currents in the world amounts to less than 2 TW.”

Geothermal energy is a potential source of electricity in some parts of the world, but the technology and cost for exploiting this source of power is uncertain. Even with substantial R & D subsidies, an MIT-led study concluded that it may be decades before the U.S. realizes significant cost-competitive electric power from geothermal resources. The amount of geothermal electricity that could be generated worldwide, based on current technology, is a small percentage of total power needs. Because geothermal generation relies on comparatively low temperatures, its efficiency and cost per kWh would benefit substantially from Neothermal’s lower temperature electric generation technology.

Ocean thermal electric generation has yet to prove economic. OTEC generates electricity by exploiting the temperature differential between warm ocean water at the surface and cooler water at a depth of 1,000 meters. A significant amount of OTEC electricity could be generated with a higher efficiency heat-to-electric conversion system than traditional methods provide. Neothermal’s conversion technology would be effective in that regard.

Solar energy is the one renewable source that far exceeds world energy use. Solar energy reaches the earth’s surface at over 1,000 times our projected rate of electricity consumption. Even allowing for the coverage of much of the earth by the oceans, there is abundant solar insolence to provide all of the world’s electric needs, if the sun’s energy can be effectively and economically harnessed.

At present, solar electric generation occurs primarily in two modes – (1) photovoltaic, which directly converts the sun’s radiation to electricity, and (2) concentrated solar power, which first heats a fluid by concentrating the sun’s radiation with mirrors, and then generates electricity from the hot fluid using a mechanical heat engine. PV remains relatively expensive. CSP is available only where solar radiation undergoes minimal diffusion before striking the earth’s surface so that it can be focused on the target. In the U.S., for example, the Mojave dessert and areas of Arizona are among the few places where CSP can be used effectively.

All solar energy comes to the earth in one form – electromagnetic radiation. Because Neothermal’s technology allows for direct conversion of heat to electric energy, it provides another way of turning this vast natural resource into electricity – simply create heat first from the sun’s radiation. While the temperatures achieved with existing solar absorber technology are insufficient for traditional conversion to electricity without first “concentrating” the sun’s energy to increase the temperature, Neothermal’s technology is effective at the lower temperatures reached with non-concentrated absorbers.

Biomass is, in effect, another way of using the sun’s energy to produce electricity. But while biomass is within the cost range of fossil fuels, its capacity is limited. The low efficiency with which these biofuels convert sunlight to stored energy means that large land areas would be required to generate power. For example, to produce the amount of power used in the world today, nearly all the arable land on Earth would need to be planted with switchgrass, which is the fastest-growing of these energy crops.

 

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