By Craig Miller
June 20, 2012
It’s a fair question and one that a reader posed during our recent series on “Water and Power” in California. Hydro has its virtues. It’s clean, once it’s built; producing hydropower creates no significant greenhouse gas or other emissions. And it’s certainly “renewable” as long as the water flows. But it’s not without its environmental impacts, especially where large “terminal” dams are involved (the kind that fish can’t get past).
In fact, state regulators divide the resource into “large” and “small” hydro, the latter being defined as anything producing 30 megawatts of power or less. Utilities can count small hydro toward their mandated Renewable Portfolio Standard (RPS) but not the bigger operations. But why?
Partly it’s because there is already so much hydro out there. In a wet year, Californians get about 17% of their electricity from hydro, not counting imports. The RPS is designed to encourage development of new sources, such as wind and solar.
In opposing a recent bill to count larger hydro facilities, The Utility Reform Network (TURN), a watchdog non-profit, wrote that such a reversal:
…would effectively reduce the RPS targets for utilities with existing large hydroelectric generation in their portfolios and significantly undermine the impact of the RPS program on the development of new renewable energy projects in California and the West.
TURN estimated that changing the rules would effectively reduce California’s target of 33% renewables by 2020, to 30% — even less if utilities increased imports of hydropower from neighboring states.
TURN’s analysts also argued that an over-reliance on hydro could end up raising the retail cost of electricity. That’s not entirely theoretical. At least one report calculated added costs of over a billion dollars when utilities had to shift to more expensive natural gas during a recent dry spell.
The plot twist here is that hydro is an important helper to new “intermittent” renewables like wind and solar. Hydro output can be quickly and easily throttled up or down, to keep the electrical grid in balance as the sun and wind come and go.