Environmental Engineering Reference
In-Depth Information
Wind and Solar
Both wind and solar technologies have experienced substantial growth in
recent years; they have benefited from federal and state financial incentives,
DOE's R and D programs that decreased costs and improved efficiencies, and
environmental and energy security concerns. For example, U.S. wind electric
generation capacity has grown from 2,000 megawatts in 1999 to 10,000
megawatts by August 2006, enough energy to power about 2.5 million homes[22]
with electricity on a typical day. Similarly, the total photovoltaic market has
grown, on average, about 30 percent per year over the past 10 years, according to
a solar manufacturer. In 2005, the United States had an estimated 475 megawatts
of installed photovoltaic capacity, enough to power about 240,000 homes. EIA
data show that in 2005 domestic shipments of solar photovoltaic solar technology
increased by 72 percent over 2004.
The wind energy industry faces technological challenges to improve turbine
design, performance, and reliability that will enable wind power to expand into
low wind and offshore locations. These locations use bigger wind turbines with
longer blades mounted on taller towers, requiring complex design improvements
in such areas as blade development, advanced drive train and power electronics,
and advanced controls to reduce system loads. For example, while traditional
blade materials have used fiberglass technology, the next generation of turbines
will need stiffer and stronger materials, such as carbon fiber, to make longer,
thinner, but equally durable blades. Similarly, offshore wind development faces
new technical challenges, such as understanding the effects of wave and current
loads on the base of wind structures, connecting offshore wind farms to the
electric transmission grid, and designing support structures for turbines located in
deep water.
Solar technologies also face challenges of improving the scientific
understanding of the electronic process of capturing and converting sunlight at the
molecular level and technical challenges of improving performance and
reliability. For example, DOE is pursuing thin-film photovoltaic technologies,
which are designed to reduce material costs by using thin layers of semiconductor
material. According to DOE, this technology is not as efficient in converting
sunlight to electricity as conventional crystalline-silicon solar cells, but
manufacturing costs are anticipated to be lower. The challenge is to increase their
efficiency, while continuing to reduce the costs of manufacturing thin-film
technologies. DOE scientists are also seeking to reduce failure rates for
components in solar water-heating systems that are exposed to high temperatures
and improve the 12-year tank life of current solar heaters in cold climates.
