Dads Go Green.comEasy Ways to go Green

What mass-energy storage systems are available to store energy from wind-power??

By way of example, if a two-tier reservoir system was constructed and during times of excess wind energy the surplus was used to pump water from the lower to the higher reservoir, and the water was then used to run hydro-turbines during times of lower wind energy production.
Would some type of ‘green energy battery’ like this, be one answer to the drawbacks with wind-power?

Yes

It’s so tempting to write an essay on this in here… must resist…. resiiiiist….

(1) Wind Is Not The Only Fruit

Pumped storage already exists – the UK has four stations. But they were built to balance off conventional power generation. Sizewell B nuclear PS is UK’s biggest indigenous balancing problem – if one of the two units flicks off, that takes 1320MW off the system instantly. The cross channel interconnector can take 2000MW off. Wind doesn’t do that – each turbine is autonomous, and even the largest offshore machines are never bigger than 5MW each. They don’t all flick off at once.

(2) Time Matters

Electricity balances at all instants. http://www.dynamicdemand.co.uk for more. System Operators must cater for imbalances on all timescales. They do this by:

- “instantaneous”: large consumers able to switch off if frequency drops too low.
- sub-second: spinning intertia
- seconds: head of steam
- a few more seconds to a couple of minutes: pumped storage
- minutes: reserve (standing) generation
- hours: warming instructions to large generators
- days->years: “The Market Shall Provide”…

(2) Pumped Storage

Pumped storage is the cleanest, greenest of batteries, and you get 70-80% of the energy back that you put in. It costs a kings’ ransom to build one.

(3) Compressed Air Energy Storage

USA and Germany have one plant each; think there are more in the post. Basically they divert the hot compressed air halfway through its travels through a gas turbine into a disused salt mine. It is part of a fossil power station though so it’s tricky to say how much you get back for what you put in. I’m not sure of the numbers.

(4) Deferred consumption

Industrials can stop consuming during peaks or say in the first hour after a storm-driven wind turbine shutdown to allow other plant to get going. This type of energy storage is very efficient. http://www.flexitricity.com/

(5) District heating with hot water storage

Lots of examples, mostly in Denmark. District heating takes waste heat from generators to heat hot water. If there’s a nice big hot water reservoir, then the generator can generate mostly when the wind is low while still allowing people to consume heat when they want to. http://www.emd.dk/

(6) Hydrogen and associated uses.

http://www.pure.shetland.co.uk/ – this is a really nice project involving a wind turbine, an electrolyser, some hydrogen bottles, a fuel cell, and a vehicle. The energy just nips from one to the other depending on where it’s needed.

There are other uses for hydrogen, and if you make it opportunistically when the wind is up, you’re storing energy. http://www.anglesey-wind.co.uk/ is an enterprising outfit with lots of ideas on that score.

Transport is the very obvious alternative use scenario for renewables – you just fill up the stock of H2 bottles at filling stations when your wind farms are at full tilt, and then swap them for the empty ones of passing motorists bottle by bottle. Renewable cars, howzat?

(7) Batteries

Don’t knock ‘em! Off grid power at a Youth Hostel up in the highlands of Scotland relies on hot water, lead acid batteries, and a single wind turbine. Bliss (trust me I know, I arrived there very wet and cold one day). Plus there are other batteries – http://www.pacificorp.com/Press_Release/Press_Release36434.html is a Canadian system built in Utah

(8) Fossil fuel

And this is what we actually do rely on as an energy store, and would continue to rely on if wind had never been thought of. Unconverted fuel is energy storage. Don’t blame wind for needing storage to back it up – it all needs that!

Wind Turbine – Rooftop