Page 34 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

20 Nanotechnology as a Tool for Sustainability

target of 12 percent of energy and 22 percent of electricity from renew-
able sources by 2010, including hydroelectric power.
In the United States, state governments are leading the way for the
promotion of solar energy. More than twenty states have now passed
Renewable Portfolio Standards, while fourteen states have set up
Renewable Energy Funds to subsidize or promote development of new
renewable technologies, such as solar and wind power. Clean Edge, a
research firm in Oakland, California, predicts that spending in renew-
able energy will jump to $89 billion by 2012, from $10 billion today.
With a production cost of around 20 to 30 cents per KWh for solar
energy, solar energy is not yet positioned to be a major competitor to
fossil fuels, whose electricity generation costs are as low as 2 to 3 cents
per KWh. However, distributed customer-sited photovoltaics (PVs), where
transmission and most distribution costs are avoided, is currently com-
petitive as a peaking technology with small subsidies in regions with
high levels of solar radiation. In dense urban areas with constrained
underground transmission and distribution networks, such as San
Diego, California, PVs can be competitive if the retail pricing fairly
reflects the full value of generation at peak. Solar energy has also made
inroads in Germany and Japan where overall retail electricity prices are
higher than in the United States.

Renewable Approximate Price Approximate Price R &D Goal
Resource per kilowatt hour per kilowatt hour Approximate Price
(1980) (2003) Target

Wind $0.80 $0.05 $0.03 (2012)
Solar (PV) $2.00 $0.20 – 0.30 $0.06 (2020)
Biomass $0.20 $0.10 $0.06 (2020)
Geothermal $0.15 $0.05 – 0.08 $0.04 (2010)
SOURCE: U.S. Department of Energy

Numerous challenges must be overcome to propel renewable energy
to replace fossil fuels. Solar energy can be generated through the use of
plants, through photovoltaic semiconductor junctions, and through catal-
ysis (in which water is split using sunlight, producing relatively cheap
hydrogen to produce electricity). Researchers will need to be able to
offer disruptive solar technology with inexpensive conversion systems
and effective storage systems. One option is to reduce the costs by
improving the efficiency of photovoltaic cells. Another is to lower costs
by enhancing systems to generate thermal solar energy on a larger,
more cost-effective scale. New catalysts and new integrated systems
need to be developed to help convert intermittent power into base-load
power, including new materials to convert sunlight to hydrogen and
oxygen.