4 ms·

> In the first half of this year, California tossed out more than 300,000 megawatts That doesn't sound right. According to [0] that is 2/3 of total electricity

by kees99 9y ago

> In the first half of this year, California tossed out more than 300,000 megawatts That doesn't sound right. According to [0] that is 2/3 of total electricity generated, from all sources, in the whole of US. [0] http://www.wolframalpha.com/input/?i=average+electricity+generation+in+us+in+megawatt http://www.wolframalpha.com/input/?i=average+electricity+gen...

scblock 9y ago
I have to assume that they meant megawatt-hours, a unit of energy, rather than megawatts, a unit of power.
- schainks 9y ago
  I also think that's what they meant. Painful to read that sentence from such a large media outlet. You'd think they'd have some people on staff to help double check incorrect vocab usage...
wongarsu 9y ago
How do they even "toss out" electricity? It's not like you can just open an overflow valve to get rid of it. Are there actually facilities for burning up useless electricity (to protect the mains frequency and thus the power plants' generators), or is the article just using strange words for "cut back production"?
- pjc50 9y ago
  Very small wind systems do have "dump loads", big resistors to use up spare energy and act as a brake for the turbine. The key word is "curtailment" for renewables: https://electrek.co/2017/03/27/california-solar-wind-renewable-electricity-record-high-peak/ https://electrek.co/2017/03/27/california-solar-wind-renewab... For wind farms, this just involves turning the blades on their axes like "feathering" a propellor. This reduces efficiency and hence power output, potentially to zero. Turbines may also need to feather if the wind is too high to avoid exceeding max speed. All larger systems - coal, CCGT etc - have some kind of system for throttling back input of steam or gas to turbines. Nuclear power is slightly different in that it takes a long time to cool down the reactor even once you slow the reaction, and heat is still generated from intermediate decay products. So they have "bypass" systems instead for dumping steam. All power plants have to be able to survive the loss of their upstream output load without self-destructing. In case the wires go down. Spot prices may also go negative for short periods, but that's a different thing. https://www.cleanenergywire.org/factsheets/why-power-prices-turn-negative https://www.cleanenergywire.org/factsheets/why-power-prices-...

by kees99 9y ago

scblock 9y ago

I have to assume that they meant megawatt-hours, a unit of energy, rather than megawatts, a unit of power.

schainks 9y ago
I also think that's what they meant. Painful to read that sentence from such a large media outlet. You'd think they'd have some people on staff to help double check incorrect vocab usage...

wongarsu 9y ago

How do they even "toss out" electricity? It's not like you can just open an overflow valve to get rid of it. Are there actually facilities for burning up useless electricity (to protect the mains frequency and thus the power plants' generators), or is the article just using strange words for "cut back production"?

pjc50 9y ago
Very small wind systems do have "dump loads", big resistors to use up spare energy and act as a brake for the turbine. The key word is "curtailment" for renewables: https://electrek.co/2017/03/27/california-solar-wind-renewable-electricity-record-high-peak/ https://electrek.co/2017/03/27/california-solar-wind-renewab... For wind farms, this just involves turning the blades on their axes like "feathering" a propellor. This reduces efficiency and hence power output, potentially to zero. Turbines may also need to feather if the wind is too high to avoid exceeding max speed. All larger systems - coal, CCGT etc - have some kind of system for throttling back input of steam or gas to turbines. Nuclear power is slightly different in that it takes a long time to cool down the reactor even once you slow the reaction, and heat is still generated from intermediate decay products. So they have "bypass" systems instead for dumping steam. All power plants have to be able to survive the loss of their upstream output load without self-destructing. In case the wires go down. Spot prices may also go negative for short periods, but that's a different thing. https://www.cleanenergywire.org/factsheets/why-power-prices-turn-negative https://www.cleanenergywire.org/factsheets/why-power-prices-...