Environmental Engineering Reference
In-Depth Information
a common grid, with the idea that when one location is quiet another will be strongly
contributing. The second major problem is that the best locations for collecting solar
and wind energy are often remote from population centers, with a large need for
transmission of power. A signi
cant step to reduce the need for storage, as we have
suggested above, is to combine approximately equal amounts of wind and solar
energy, with the solar energy providing the extra power needed during the daytime.
An extensive plan was produced for continental Europe and North Africa [145],
concluding that with large use of DC power transmission lines and undersea cables,
which are more ef
cient at longer transmission distances, the whole area could be
serviced with renewable energy, without need for oil and coal, and at costs similar to
present costs. An optimization resulted in clustering renewable wind- and sun-based
sources where the conditions are optimum, notably in North Africa, and sending the
energy to population centers with extensive use of DC power transmission lines. In
the United States, this would suggest putting most of the solar cells in the far
southwest, see Figure 1.7b. The optimization favored wind over solar on a cost basis,
and in the category of solar favored solar thermal, known also as concentrated solar
power (see Section 5.3) over solar cells on a cost basis and because of its option of heat
energy storage, based on molten salts. The optimization also included Norway,
despite the expense of undersea transmission cables, because of its storage capacity.
In this chapter, we have examined, from a simpli
ed technical point of view,
approaches to replacing U.S. electric production entirely by renewable technology,
emphasizing photovoltaic cells, with crude estimates on costs and comments on
storage and gridmanagement. InChapter 11, we will venture some estimates of what
may actually happen, taking into account external factors that include the worlds
reaction to the growing recognition of climate change as associated with carbon-
based energy, and the variability among countries in the ef
ciency of their political
processes toward recognizing and acting on needs for change.
