Environmental Engineering Reference
In-Depth Information
capacity during the next 25 years are ethanol, a partial substitute for gasoline in
transportation, and wind and solar energy technologies for generating electricity.
For advanced fossil technologies, the primary challenge is controlling emissions
of mercury and carbon dioxide generated by conventional coal-fired plants by
using coal gasification technologies that cost about 20 percent more to construct
than conventional coal-fired plants and demonstrating the technological feasibility
of the long-term storage of carbon dioxide captured by a large-scale coal-fired
power plant. For advanced nuclear technologies, investors face substantial risk
because of nuclear reactors' high capital costs and long construction time frames
and uncertainty about the Nuclear Regulatory Commission's (NRC) review of
license applications for new reactors.
One of ethanol's biggest challenges is to cost-effectively produce ethanol
while diversifying the biomass energy sources so it can grow from its current 3-
percent market share. DOE is exploring technologies to use cellulosic biomass
from, for example, agricultural residues or fast-growing grasses and trees. In
addition, ethanol requires an independent transportation, storage, and distribution
infrastructure because its corrosive qualities and water solubility prevent it from
using, for example, existing oil pipelines to transport the product from the
Midwest to the east or west coasts. As a result, fewer than 1,000 fueling stations
nationwide provide E85 compared with 176,000 stations that dispense gasoline.
Ethanol also needs to become more cost competitive. Even with the recent spikes
in gasoline prices, ethanol producers rely on federal tax incentives to compete. In
October 2006,
Consumer Reports
estimated that drivers paying $2.91 per
gallon for E85 actually paid about $3.99 for the energy equivalent amount of a
gallon of gasoline because the distance vehicles traveled per gallon declined by 27
percent. Finally, congressional earmarks of DOE's biomass R and D funding rose
from 14 percent of the fiscal year 2000 funds to 57 percent ($52 million) of the
fiscal year 2006 funds, according to a DOE program official.
Both wind and solar technologies have experienced substantial growth in
recent years, but both wind and solar technologies face important challenges for
future growth. In particular, wind investors pay substantial upfront capital costs to
build a wind farm and connect the farm to the power transmission grid, which can
cost $100,000 or more per mile on average, according to DOE officials. Because
both wind energy and solar energy are intermittent, utilities have been skeptical
about using them, relying instead on large baseload power plants that operate full
time and are more accessible to the transmission grid. In contrast, wind turbines
operate the equivalent of less than 40 percent of the hours in a year because of the
intermittency of wind. In addition, the electricity that is generated must be
