Reasons to be cheerful

My Grid GB 28 daysWhen everything feels rubbish, it is sometimes calming to remind oneself that progress in human affairs is possible.

Solar Energy in the UK!

Looking at the MyGrid GB site I notice that the longer brighter days are leading to significant solar power generation every day – the yellow in the figure above and below.

My Grid GB 48 hours

Over the last month, solar power has contributed more than 5% of the UK’s electricity supply. I find this truly astonishing.

The electricity comes from solar panels on people’s rooftops, and from large solar ‘farms’ – which can still be used to graze sheep!

It is clear that solar energy generation is well matched to the demand for electricity – peaking every day at around 1:00 p.m. BST.

Storing the energy

We could certainly generate two or three times as much solar energy as this with relatively low impact. But imagine how cool it would be if we could store some of that energy as it was generated, and then release it exactly when we most needed it.

Over the last year I have noticed that ‘energy storage’ has gone from being ‘a great thing if it existed‘ to ‘a reality on a small but ever-growing scale‘.

Here are five ideas I have seen recently. They don’t have much in common, but I am collecting them together simply to hearten myself.

One of the ideas pumps water as an energy storage medium, one compresses air, one uses ice, and another is just a big battery! And one is just a cool idea whose point I don’t quite understand!

Pumping Water

At the Dinorwig power station (earlier blog) water is pumped uphill at night and released at times of peak demand to generate electricity. Dinorwig stores approximately 10 GWh of energy with approximately 75% efficiency – enough to generate 1.8 GW of electricity for approximately 6 hours.

But sites such as Dinorwig are rare. What if the same trick could be done in a more mundane way?

Ars Technica describes a sweet idea in which 30 metre diameter concrete spheres – each containing a pump-generator set – would be placed deep underwater.

Positioned near a wind farm, wind-generated electricity could be used to pump water out of the sphere against the enormous head of a few hundred metres of water. When electricity was required, water could be let back in, generating electricity.

They report that each sphere could generate 5 MW for 4 hours. So a Dinorwig-scale installation would require 500 spheres – which would probably occupy about 1 square kilometre of sea bed.

German Undersea Spheres

Less practically, The Independent have a story describing an artificial island in the North Sea that could form a hub of a renewable energy facility.

NOrth Sea Island

I don’t quite know what the point of the island would be, but I love the sheer chutzpah of the proposal.

Compressing Air

Much more practically, the Hydrostor Terra company have a plan to store energy as compressed air in scale-able plants built by a lakeside.

Interestingly – and showing a reassuring contact with reality – they separately store and recover the heat generated  when the air is compressed. This is the key to getting a reasonable efficiency.

It would take perhaps a thousand of these systems to create a Dinorwig-scale storage facility. However, because the system is scale-able, small systems could be built and put into operation quickly, with the revenue being used to fund the creation of expanded storage over the coming decades.

This ‘scale-ability’ avoids the need for billions of pounds to be invested up front and is important for demonstrating new technologies.

Ice Batteries

In the here and now, I love this idea of power companies subsidising the purchase of equipment which will lower demand for electricity rather than simply building more capacity.

In this scheme, air conditioning plant is run off-peak to create a store of around 2 cubic metres of ice. The ice is then used to chill air at times of peak demand.

In a way this is really ‘demand management’ rather than ‘energy storage’, but it achieves the same effect.

Ice Storage

Tesla Batteries

And finally, the obvious idea of storing electricity in batteries! This story reports on an an actual real functioning 80 MWh storage facility in California that can deliver 20 MW of electricity for 4 hours.

It would take 120 of these installations to create a Dinorwig Scale facility, but because each unit can be built independently, it does not require investment at the same scale and risk as that required to build a Dinorwig.

Energy Storage has arrived

The problem of grid scale energy storage has many solutions, and they are available now using current engineering practices.

My hope is that the growth of energy storage will surprise me in the same way that the the growth of solar energy has suprised me.

I hope that one day soon I will look at the chart on MyGrid GB and see that the wind supply is smooth not spiky – and that solar power is supplying electricity after the sun has gone down!

One Response to “Reasons to be cheerful”

  1. Ed Davies Says:

    Here’s a longer-term use of ice for energy storage by a couple (both physicists) in Austria:

    https://elkement.blog/2016/01/07/how-does-it-work-the-heat-pump-system-that-is/

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