Is there really such a thing as excess output in a country? I’m imagining a country’s generation and usage to be represented by V = IR, where V is your potential difference, I is the amount of electricity generated, and R is consumption. I saw a listing of average kilowatt-hour consumption per person-year for different European countries and it surprised me. Maybe it has more to do with capacity to generate than actual propensity to use.
High latitude countries are the ones who consume in 5 figures (Finland, Iceland, Norway, Sweden.) The odd country here is Luxembourg who consumes almost as much as Finland per person-year. The major industrial countries like Germany, France, and UK score Low.
There are various inefficiencies in the system (generation, delivery) that just vanish into heat.
Countries with excess generating capability also export to other countries.
Consumption also depends on level of industry in that country and the need for heating or cooling, so it should vary by area. Iceland, for example, has its aluminum industry using 71% of its consumption: Electricity sector in Iceland - Wikipedia
Excess output is quickly scaled back at the generating sources. Excess capacity is usually a good idea in case of extreme demands. Production is ramped up as demand increases. Most generation sources have multiple generators that can be brought on or taken off line. Some sources are quicker and easier to switch on and off, others not so much.
My province can handle most peak demand internally, as well as sell. At night, our generators often sell to a neighboring province, that sometimes pumps water back up behind their dams, to ensure a good supply of hydro electric the next day.
A significant part of the supply authority’s job, is to balance supply and demand. A lot of it is predictable and they keep a close eye on popular television events, as demand will surge at the end as people make tea/coffee or start cooking.
We now have a crazy situation in the UK, as mainstream generators are paid to keep plant on standby in case the wind drops and the so called green generators wind farms stop working.
People don’t build electric generation plants just to have them sit idle for 300 days a year. You basically have to guarantee them that they will make at least the same profits on those plants as if they were fully operational or else they will invest their money in something else.
So basically, you need to have as much non-wind capacity sitting idle most days of the year as you have wind capacity and you have to pay the owners of the non-wind capacity for not producing electricity.
You mean that normal for-profit companies would try not to do this.
But in places with government regulation, the regulatory agency may indeed demand that sufficient demand be built to cover the heaviest uses whether or not they are out of production 300 days a year.
Yes, of course. But then the government must either subsidize the costs through taxes, let the regulated rate rise enough to cover the costs of building and then maintaining all of the plants on ready standby, or see the operators of those plants go bankrupt.
Right. Most people don’t understand this. They imagine a fairyland in which all fossil fuel plants can be immediately shut down. They can’t conceive that as long as wind and sun are intermittent, a dual system must be maintained. (And mentioning that natural gas is itself a system blows their tiny minds.)
The answer would be nuclear but that has other issues.
Yes they do. Some plants may only start up 5 or six times per year. Those plants are peaking plants and they may only operate during extreme seasons and/or conditions.
Typically a peaking plant costs much less to build but uses expensive fuel. A coal plant might cost around $3000/kw to build while a combustion turbine plant would be less than $1000/kw.
So year round a coal plant with an output cost of $30/MWH would stay in service day and night but a combustion turbine with a $70/MWH would only be started up on heavy load days (in the midwest USA those heavy load days are typically hot summer days).
I haven’t priced power plants in a while so my numbers may not be accurate but they are scaled appropriately.
Many days they aren’t. But if there is even a chance that prices climb high enough for them to be committed then they would be entered into auction.
Keep in mind that during peak times prices climb very high and all producers get the market price so those plants are profitable because during the few times per year that they operate they are making very good money.
Also understand that most plants are owned by utilities or large investors who may operate a portfolio of different plants in the market.
The risk they are taking by owning a seldom used plant is somewhat hedged by their portfolio. A plant may not be profitable 2 out of 5 years but the other three years may more than offset the financial loss of the 2 lean years.