Since May when this year's above-normal water runoff began being felt fully, some 6,000 to 7,000 MW of thermal (natural gas and coal-fired) generation has been shut down, a Bonneville Power Administration (BPA) spokesperson in Portland, OR, told NGI Friday.
BPA reports that through last Wednesday it had curtailed 11,000 MWh of thermal generated electricity and an average of 6.2% of wind, but for the thermal supplies the number is misleading, the spokesperson explained. Most gas- and coal-fired generation has been virtually shut down since May began because of the abundance of cheap hydroelectric supplies in the federal power system.
"It was simply a matter of economics because of all this inexpensive hydropower out there, so most of those [thermal] plants shut down of their own accord," said BPA spokesperson Michael Milstein. "When we get to the point that most of that generation is offline, but we still need to reduce generation further, we go to anyone that is still online in our system and direct them to curtail."
Thus, the amount of BPA-directed curtailment of thermal generation is a relatively small part of the total gas- and coal-fired generation that isn't operating right now. "It is just a share of what would otherwise be online," Milstein said. "Virtually for the past weeks there has been little thermal generation, if any, operating in our system."
What is operating still is usually cogeneration installations at a sawmill or some other industrial setting, he said. In these cases, the end-users are generating power as part of their normal operations and they would have to shut their production line. What remains online is around 100 MW of gas-fired power, compared to the 6,000-7,000 MW of thermal-based power in the region.
While the thermal plants are almost totally off, the amounts of wind that are having to be curtailed appear to be much smaller than in the initial weeks of the big water runoff in early May. Milstein called the amounts of wind curtailment "fairly limited -- several nights in the last couple of weeks. In the past two weeks, cutbacks have dropped 2%," he said.
Nevertheless, wind operators have filed a complaint with federal regulators, alleging that BPA broke contracts and discriminated against them when imposing the cutbacks, according to an Associated Press report.
A nonprofit group advocating for renewable power operators in the region, Renewable Northwest Project, has told local media BPA is setting bad precedent and the group will file a complaint soon.
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