Seasonal storage combined with current battery technology is the future.
The problem we have in the UK is that our solar generation is very much seasonal, and of course the majority of it happens when we need it the least. This will become even more pronounced a problem as we transition away from using gas to heat our homes. Heat pumps are way more efficient, but the cost of installing and running them outweighs the benefits for a large number of homeowners, myself included.
For six months of the year, the solar panels on my house are going to generate more electricity than I can use or store, and that excess is exported to the grid, generally at times of least demand. At the moment it makes financial sense to export that energy, but that is not going to continue. Export prices have recently dropped by 25%, and that downward trajectory is only going to continue.
I have 10kWh of battery storage, which allows me to run almost entirely from off peak electricity through the winter, but between that and the gas I use to heat my home, my bills are still not where I want them to be in winter. Were I to switch to electric heating, that 10kWh of storage would not be anywhere near adequate. I would probably need closer to 50kWh, and that starts to become expensive. There are ways to see return – I could for example switch to agile export and use the extra storage to export during peaks to maximise revenue, or register with a VPP aggregator such as Axle and have them utilise the extra capacity.
Ideally, what is needed for homes like mine is to move towards greater self sufficiency and away from importing energy. This is the ultimate protection against price shocks and any kind of energy instability. The way to achieve this is through seasonal storage: capturing and storing that excess generation in the summer and using it through winter. This is a very hard thing to achieve, particularly on such a small scale. Long term storage using current technologies tends to be very inefficient, and only works well at scale. I have looked at a couple of ideas being developed, and although interesting I don’t think they are quite there yet.
The first is sand batteries: basically a big insulated box of sand is buried in your garden, and is heated with excess energy. That heat is then used when required to heat either water or air in your home in winter. I don’t know what the round trip efficiency is, but I don’t expect it to be great. Its not really a practical solution for many, but it could work for some homes More info here: https://www.batsand.com/heating-battery
The second is Hydrogen fuel cells: excess energy is converted to hydrogen through electrolysis, which is then converted back to electricity via fuel cells. There are systems available, but they are very expensive, large and unwieldy. Hopefully this will change as the technology gradually improves, and becomes more affordable. There are companies offering systems at the moment such as: https://creouk.com/hydrogen-systems/
Season storage is not yet affordable or practical for those without large homes and deep pockets, but the technology is evolving, and I hope will soon mature to a point where it does start to make sense in both practical and financial terms. Seasonal storage combined with short term battery and solar technology that we already have will eventually lead to energy independence for many homes and businesses, reducing reliance on the grid, and also reducing the need for the massive infrastructure required to transmit energy over long distances. Localised generation and storage is surely the way forward.
Leave a Reply