8209 - Laserfiche WebLink

Home Browse Search

well as the seasons of the year. The demand that must be supplied con- tinuously is called the baseload; usually nuclear or coal-fired thermal plants supply the baseload because they operate most efficiently at a steady, large output and require long lead times to start up and cool down. Large, main stream hydroelectric plants also help meet the baseload demand. Small hydro plants also can produce electricity continuously as long as flows are steady, but are technically well suited to satisfy peak demands because rapid changes in output can be made by regulating the discharge through the turbines. The market value of the electricity from a hydro plant normally is related to the costs of competing sources of electric power although, in some States, the value of hydroelectric output is now set by law. When costs for meeting peak daily or seasonal demands by fuel-consuming steam driven generators are high, as is often the case where fuel is expensive or the existing thermal plants are small and inefficient, SSH may plan an ef- fective role in replacing these plants. Thus, store and release (peaking, see Chapter 7.2) operation of a SSH plant may be its most valuable role economically, provided that there is sufficient reservoir capacity avail- able. On the other hand, site limitations may make operating in a peaking. mode impracti'cal. These constraints may include the requirement to main- tain reasonably steady flows for fish and wildlife, recreation, or down- stream water consumers. Even then, SSH may be economically feasible, although perhaps not as profitable. Small hydro plants can be used to provide additional economic benefits from facilities used primarily for other purposes, such as when electric power generated in irrigation canals is used to pump water out of the canal into the fields. In certain circumstances, a SSH facility may provide historical and educational benefits, such as when a former hydroelectric plant or water-driven industrial mill is restored for use; this activity is particularly common in New England. Recreational activities may be improved if an impoundment is created or when a damsite is provided with access roads, which also benefits boaters, hunters, and fishermen. 2.1.2 Fish, Wildlife, and Environmental Opportunities SSH is not totally environmentally harmless. There are, however, some positive aspects to this technology that should not be overlooked when comparing it to other energy sources. When a dam is constructed new warm water fish habitat or wetlands often are created. These may be beneficial in parts of the country where open water is scarce. Likewise, a dam can be used to regulate flows to the benefit of fish and wildlife, as in creating a tailwater fishery. In some places, the fish-blocking effect of a dam (a negative impact where anadromous fish are involved) can be used to keep fish populations separate for management purposes. When a proposal is made to rehabilitate an existing facility, improvements in fish and wildlife protect i on at the site may be i nc 1 uded as a cond it i on for permi t t i ng SSH development, resulting in an overall improvement in fish and wil~life 12