Sustainable Energy Alternatives for the Southwest - Design with the Desert: Conservation and Sustainable Development - page 509

into the electric grid are generally low, at least until the proportion of power generated
by these resources reaches roughly 20% of total power generation. 13 However, changes to
the way the electric grid is operated could reduce the costs of integrating higher levels of
intermittent renewable energy. 14
Also, solar power is not available when the sun is not shining unless the generation
facility can store energy. Some solar technologies do store energy—for example, CSP using
parabolic troughs or central receivers can be designed to store heat to make steam to power
a generator in the evening or other hours when the sun is not shining. Solar hot water
systems store hot water in a tank for use when the consumer demands hot water.
Solar power plants based on a steam technology with conventional cooling consume
large amounts of water—perhaps over 700 gal/MWh. Dry cooling could be used, but at
additional cost and with lowered power production efficiency.15 15
Large scale renewable energy projects in the desert may interfere with wildlife and
disrupt local habitat. For instance, wind turbines, if not carefully sited, can kill birds or
bats. 16 Large solar energy projects can take up hundreds or even thousands of acres and
may disturb desert tortoise or other habitat. However, some solar projects could be located
on what is currently farmland or industrial or mining land, thereby avoiding undisturbed
wildlife habitat (and which might come with water rights).
Some renewable energy technologies are more costly than their conventional
counterparts. Various incentives, such as production tax credits, investment tax credits,
and utility incentives for distributed energy projects, often lower the effective cost to
the project owner. Broadly speaking, wind, geothermal, and some biomass plants are
currently cost competitive with conventional generation, but most solar technologies are
more expensive. Costs for PV facilities have decreased recently and may be on a path
toward a competitive price.
New large hydropower projects are unlikely because there are few sites left that could
accommodate these projects, because of their environmental impacts, and because long-
term drought will reduce their power output. Some small hydro projects are possible, such
as Salt River Project's 750 kW plant on the Arizona Canal in Phoenix.
Table 29.1 provides a summary comparison of coal- and gas-fired generation and some
major clean energy resources that are likely to be developed over the next 10-20 years.*
29.5 Diminishing Role of Coal-Fired Power Plants
California's emissions performance standard is an important policy affecting existing and
new coal plants serving California customers. The standard for new baseload power gen-
eration is 1100 lb of carbon dioxide per MWh. The standard applies to long-term contracts
or ownership of baseload power plants, whether the power plant is located in California
or elsewhere. The impact of the standard is to eliminate use of new conventional coal-fired
power plants or new long-term contracts for purchases from conventional coal-fired power
* This chapter does not address the role of nuclear power in the future. While nuclear power has its advocates
and some utilities are actively exploring additional nuclear power, its role is very unclear. There is no recent
experience with building nuclear power plants in the U.S. Construction costs are likely to be high, but the
absence of recent experience means that reliable projections of cost and of performance characteristics during
early years of operation are not available. And there remains the problem of safe long-term storage of radioac-
tive waste—a political controversy that apparently is unsolvable.