Hacker News Reader

Comment by krschultz | Hacker News Reader

It's certainly cleaner as mentioned in the other comment.

Another factor is that natural gas turbines can be turned on and off more quickly than coal fired plants. This is because a gas turbine is literally burning the gas in the turbine, it's akin to a jet engine on an airplane you can throttle up and down. A coal fired power plant is really a boiler that creates steam, and then the steam is fed through a turbine. Heating up all the water to make steam actually takes a long time.

In an era of renewable energy sources (solar, wind) that fluctuate more unpredictably, having that "dispatchability" is really valuable.

http://www.nrel.gov/docs/fy12osti/55433.pdf

View on HN

This brings up a very important point. Electricity supply must be carefully balanced with demand and so that's why most regions have ISO (independent system operators) to facilitate the coordination needed to maintain system balance.

Typically coal and nuclear power plants are "base" load stations, providing always-on capacity. It's not always possible to vary their output to match demand, so typically (natural) gas power plants are used to match the remaining variable load. The start up/shut down cycle for these plants is far less costly.

There's live stats for the UK's national grid. There's a couple of sites that show it, e.g. http://gridwatch.co.uk/

Really interesting to see.

Britain also has the interesting culture of tea drinking in the evenings - almost all using electric kettles. I believe the grid uses hydro stations to cover the load of this. Typically peaks during breaks and/or after popular TV shows in the evening.

That used to be the case, yes. Since the arrival of many-channel TV and changed viewing habits (e.g. lots more internet use) the advert-break-effect has lessened considerably.

If you were to turn off the coal supply, wouldn't the boiler quickly lose heat, particularly since we're extracting energy from it?

Even if it takes an hour to cool down, since daily and weekly patterns are generally known, can't they reduce or stop the coal supply an hour in advance?

In a world with more renewable energy, perhaps coal plants can be designed with smaller boilers, to strike a different tradeoff?

You are burning a lot of coal for no energy if you spend an hour a day starting and an hour a day stopping a plant.

I assume "less energy", not "no energy", but in any case, what better alternative would you suggest in a grid with significant amounts of intermittent sources, like 70%?

Pumped hydro or battery storage are one possibility. Smart pricing to industry who can throttle back usage if demand outstrips supply is another.

Or some combo of both of them.

Coal plants are not designed to be constantly started and stopped. For one, constantly cooling and reheating the equipment would damage the metal.

That may be true historically, but is it not possible to design them in the future with that goal in mind?

Reply on news.ycombinator.com