Environmental Engineering Reference
In-Depth Information
29.4 Alternative Energy Resources
How can utilities and the public manage the environmental and economic risks of
continued reliance on conventional power plants? A portfolio of renewable energy and
energy efficiency can, to a large extent, provide a hedge (Figure 29.4).
The first resource alternative is energy efficiency. Using energy more efficiently means
using less energy to attain the same outcome such as lighting, space cooling, water
heating, motor power, and so forth. Greater efficiency can be achieved by substituting
more advanced technology for older technology, by changing physical designs, and by
changing behavior. In general, energy efficiency is less costly than generating electricity.
We will discuss energy efficiency in more detail later.
Second, many renewable energy technologies can help utilities manage environmental
and price risks. Renewable resources available in the desert Southwest include solar energy,
wind energy, geothermal energy (which produces electricity using heat from the earth's
crust), and some biomass resources such as landfill gas, gas from treatment of wastewater,
and wood or agricultural waste. Solar energy includes a variety of technologies—only the
major ones currently in use are discussed here. Photovoltaic (PV) technologies generate
electricity directly from sunlight. Concentrating solar power (CSP) plants concentrate
sunlight using mirrors to heat a transfer fluid which, in turn, makes steam for a turbine
and generator. CSP plants may use parabolic troughs or a central receiver (power tower).
Solar hot water for residential or business use is also a solar energy resource. In general,
these renewable resources have little or no air emissions and so their costs would not be
affected by future environmental regulations. Further, most use no fuel (biomass being the
exception), so they are not subject to potentially high prices for fuel. For most renewable
energy technologies, the major cost component is the fixed capital cost of the plant.
Consequently, renewable energy is a stably priced resource that serves as a hedge against
high fuel and environmental regulation compliance costs of conventional generation.
Renewable energy is not a perfect substitute for current power generation technologies,
however. Some renewable resources are intermittent (wind and to some extent solar)
and the power supply system has to accommodate rapid changes in output of these
renewable energy generation resources. The costs of integrating intermittent resources
Energy efficiency
Efficient devices
Efficient design
Changes in behavior
Distributed resources
Renewable energy
Other (e.g., CHP)
Central station renewable resources
CSP, PV, wind, geothermal
Other central station supply resources
Natural gas-fired resources
Other
FIGURE 29.4
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