The UK plans to build huge batteries to store renewable energy – but there’s a much cheaper solution writes Andrew Cruden, Professor of Energy Technology at the University of Southampton
The UK electricity system is undergoing significant and rapid change. It has the world’s largest installed capacity of offshore wind, has effectively stopped generating electricity from coal, and has recorded a 20% drop in demand since the start of the COVID-19 pandemic.
However, this transition from traditional, reliable coal to weather-dependent wind and solar generation brings with it increasing challenges to match electrical supply and demand at every instant. This is where large grid-scale energy storage systems could help regulate and buffer supply and demand, and improve grid control.
The UK government recently announced the removal of planning barriers to building energy storage projects over 50MW in England and 350MW in Wales. This, the government feels, will enable the creation of significant new energy storage capacity. The UK currently has 1GW of operational battery storage units and an additional 13.5GW of battery projects under development at the planning stage.
This intervention by the government creates a planning environment that could enable the UK to reach its target of net zero carbon emissions by 2050. This could happen with either a high proportion of large-scale, centralised renewable generation, or with more of a priority on smaller community schemes such as locally owned wind turbines and solar panels. Batteries will, in particular, contribute significantly to the grid regulation of a further 30GW of offshore wind by 2030 (to achieve the UK target of 40GW of offshore wind by that year).
But pursuing ever larger, stationary battery systems may not be the optimal solution for the UK to have a renewable energy future. Instead, the answer could lie in the country’s garages and car parks.
As the UK has moved from fossil fuel to renewable energy electricity generation, CO₂ emissions from the energy supply sector have fallen from over 40% of the UK total in 1990 to 25% in 2019. This means the transport sector is now the largest emitter, producing a third of all UK CO₂ emissions.
This has led to a growing focus on the introduction of plug-in hybrid and all-electric vehicles. As just one in ten cars sold in the UK fall into the these categories, there is still some way to go to reducing the impact of petrol and diesel vehicles. Significantly more infrastructure is needed to support them, and their growing popularity increases the amount of electricity that the grid needs to provide, one-third of which is still produced from natural gas.
However, electric vehicles could also help with making electricity production greener. When an electric vehicle is plugged in for re-charging, it is effectively enabling the electricity grid to access its battery. When you have many vehicles all plugged in at once, they create a very large aggregated battery store. This is a concept known as vehicle-to-grid (V2G), and could create a much larger and cheaper alternative energy store than stationary large battery systems.
There are 38.2m licensed vehicles in the UK, including some 31.5m cars. If these were all battery electric vehicles (each storing an average of 50kWh of energy and connected via a 7kW charger), this could create a nationwide distributed mega battery with a capacity of 220.5GW. This would be over 15 times the size of the currently planned large battery storage.
Cheaper option
The costs of this aggregated battery would also be much easier to bear as individual vehicle owners would purchase the cars and batteries, instead of government and private investors having to spend millions on big projects. The cost of electric vehicle batteries has fallen some 87% over the last ten years to an average of US$156/kWh (£123/kWh), and is on a trajectory to reach around US$100/kWh by 2023.
Large grid-scale stationary battery system costs are at least double this amount. This is because civil engineering works, cabling, enclosures, power electronics and even air conditioning systems for regulating battery temperature are all required for large stationary battery systems.
Vehicle-to-grid storage is still a nascent concept. It requires dedicated two-way charging equipment that can also communicate with the vehicles, as well high-level aggregator control systems. However all of this technology exists.
Indeed there are a range of V2G demonstrator projects within the UK. Nissan, in particular, has embraced this technology and already offers a more limited_ vehicle-to-home (V2H) system that lets people use their cars to store energy from rooftop solar panels until it is needed in the home at night.
So while the UK government is correct that the national grid needs more energy storage to support the shift to further renewable energy generation, a focus on building large, expensive batteries isn’t necessarily the answer. Instead, electric vehicles could enable the British public to conveniently share their cars to help create a cleaner, more altruistic post-COVID world.
Andrew Cruden, Professor of Energy Technology, University of Southampton
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Is power and energy confused?
It would be good to know how this would work. At the moment your electric car spends a lot of time fully charged waiting to be used. If its battery was used in a V2G scheme would it mean that the battery would no be fully charged when it was needed? The idea of using old electric car batteries sounds a lot better, albeit with a lot slower start as you have to wait for the batteries to age.
As I understand it, you would charge your car off-peak at night for 5p Kwh drive to work or work from home as is now popular then sell any remaining charge you don’t need at peak time between 5:00 pm to 7:00 pm for 15p Kwh. You would be able to reserve how much you wanted to keep in your car, say 50% so for a 50 Kwh battery you would have 25 Kwh available for driving during the day and selling at peak times, so if your commute is 50 miles you would only use 12.5Kwh so could sell the remaining 12.5Kwh back to the grid and then replenish it over night, netting a small profit of 12.5 kwh x 10p = £1.25 per day which will cover the cost of your charging making electric cars effectively free to use.
The wind doesn’t blow and the sun doesn’t shine on a scale of weeks in January and February, the time of maximum demand. Battery storage that lasts hours will not cover the gap. Tidal power is predictable and requires hours of storage to cover the gaps. A tidal system that met maximum demand on a neap tide could be designed with or without storage. There would spring tides in the summer generating a giantic power surplus usable for hydrogen production as a diesel and fuel oil replacement. No place for windmills or solar panels at all.
It seems like it. There is a switch from meaningless GW of batteries (how many minutes does 1 Gw of installed capacity last?) to GWh in the piece.
For this to work the consumer would need:
1] To be paid significantly more for feeding power back to the grid than it costs to charge the batteries from the grid (to offset the aging of the batteries and inconvenience of not having a fully topped up car anymore)
2] To be able to limit the amount that the batteries would be discharged to so that they would still have a useful range on their vehicle
3] To be easily able to adjust this limit so that if a long journey was anticipated the following day they could decline from contributing power on the day in question.
It may come but I’m still waiting for the smart electricity meter I was promised a decade ago.
There is the small matter of loss of battery life due to the repeated use by V2G, who pays for thata?
A “Nice little earner” would be to buy say 100kWh of battery storage and charge / discharge this every day. If buying price (overnight) is 5 p/kWh – (can actually be negative if capacity grows too fast), then sell at 15p/kWh gives £ 10 / day = £ 3650 / year. At £ 123 / kWh, which seems about right for Tesla batteries, the capital outlay is £ 12,300. Simple payback is about 3 years: where’s the catch??? There is also a capacity payment for having power available, but that is just a bonus.
Unfortunately, the fire brigade are warning of the risk of serious and very difficult battery fires when these are charged or discharged at the wrong temperature – so maybe I’ll give this “nice little earner” a miss.
Just to correct Philip Owen’s contribution – every month there are 2 Spring Tide maxima [at New Moon and Full Moon] and similarly 2 Neap Tide minima [at half moons] – Spring and Neap refer to tidal range rather than the time of year they occur.
Like nearly all of these articles, there is no mention of who pays and how much for all of this “infrastructure”. As mentioned above, to be viable there would have to be an incentive to allow the grid to access your battery. Someone eventually gets the bill for this and as now it will be the people at the bottom of the pile who can least afford it.
Doesn’t seem to cover the fast approaching deficit of power production issue either.
An idea from the back of a fag packet! Using the parked vehicles to supplement the grid appears sensible. But what happens when someone needs or wishes to use their vehicle expecting it to be fully charged and it isn’t! This coupled with the woefully inadequate charging infrastructure merely adds to range anxiety. If implemented it must have the ability for users to opt-in and out as they require. Far better to use end of life vehicle batteries, ie which have reduced efficiency, for this static purpose, prior to them being recycled, as part of that final stage process.
Oh dear. Most comments seem to be missing the point I believe. Battery technology is moving at such a pace! Million mile battery isn’t to allow the car to run 1m miles it’s to allow it to be used as storage device for just the purpose described in the article. 100Kwh car battery isn’t to allow us to drive 500 mile journeys every day but if we do need this then just plan ahead and stop the grid taking it. Decentralising the power will be much more reliable, safer, lower cost, less reliable on big comapnies, lower co2 emitting! There are many more!
I think Philip Owen’s point was that if there was enough capacity for maximum winter demand on neap tides there would be significant surplus power on spring tides in the summer months to produce the hydrogen.
A free lunch no but efficient use of exisiting resources yes. Including 20 percent of your battery in scheme to to help pay for your car seems pretty straight forward. We happily park explosive flammable liquid filled vehicles in garages every day so worrying about battery fires while legitimate should not be overblown (pun intended). Range anxiety is falling as battery capacity rises annually. I don’t panic every night when my car is only 3/4 full of petrol, and if I need every volt for a journey one day I will unplug when full! Nice little earner every other day. It’s all academic though as it’s already happening in South Australia in a pilot program and elsewhere. So it’s coming, what will hold it up will be the slow roll out of electric cars by mainstream auto makers trying to protect their investments in diesel and petrol vehicle production – poor guys, trying to prevent the tides referred to earlier. As for who pays, the price of electricity now pays for the infrastructure (Coal and gas and uranium extraction transportation etc – costs for which will only rise) nothing would change except as is proven already the cost of renewable electricity seems to fall every year So the cost to all users should fall too if a little slower with Incorporation of firming technologies like pumped hydro batteries et al – chance to be on the right side of history count me in
Possibly the confusion between power and energy arises from a misunderstanding about the economics of battery storage. They are NOT generally in the business of ‘time-shifting’ energy from cheap to expensive times of day, rather they are standby devices that can be rapidly (<1 sec.) brought online to stabilise the National Grid via e.g. the Enhanced Frequency Response. The owners' receive a payment based on the raw power available (MW) to deliver this 'karate punch'; endurance is a secondary consideration. In the absence of other information you could assume ½ hour from fully charged to discharged so a 10 MW (power) battery might store 5 MW-h (energy)
The economics of repurposing such a system depends on the tariff basis for buying and selling at different times of day. Unless there is some subsidy scheme I'm unaware of I doubt the 5p/15p per kW-h (£50/£150 per MW-h) differential quoted above could be achieved (who would pay it?); for wholesale market prices see here: https://www.nordpoolgroup.com/Market-data1/#/n2ex/table
My fingers are still crossed for the development more sustainable sodium-ion batteries for bulk energy storage. Either that we use small modular reactors so we don’t have to rely on storage.
I don’t want to discover what I thought was my fully charged car ‘isn’t’ when I need it.
So the driver pays over the odds for an electric car, then pays for the electricity to charge it overnight, effectively gives that electricity back to the grid and then pays for it again to use it during the day. Seems like a win all round (except for the driver of course). The only thing renewable seems to be the ripping off of the public needlessly being pushed towards electric vehicles.
Wasn’t the Engineer telling us recently that private ownership of cars would sharply decline in favour of self-driving pool cars?
That essentially scraps this whole concept – people in or near a significant urban area will be using pool cars that ought to be busy the vast majority of the time (or the pool is oversized) and people not in or near a significant urban area will be wanting to keep their batteries full for the longer journeys that will be their norm.
If electric cars cannot reduce the direct cost of travel, then they are basically a fashion statement; a ‘Veblen good’ .
An analogy would be buying a Rolls and have the most expensive component (e.g. the leather seats) being rented out overnight to strangers, on the risible basis that it would ‘make it more affordable’?
If it is overnight electric storage that is needed I wonder what the author thinks about LAES technology?
This all seems to suggest the need for a massive increase in grid capacity. Who pays for this? What happens if there is an outage on the main 400 kv system and it is locked off the distribution networks?
In 2019 the demand for electricity was 345,000 Gigawatt hours – which, per week, is about 7,000 Gigawatt hours.
At 50 kWhrs/per car and 38.5 million vehicles the suggested mode of storage equates to 38.5×50 GWhrs i.e. 1925 (slightly less than 2 days of backup).
So, if the wind drops (and associated power is negligible) then people would need to stop using their vehicles for 2 days – and pray, too, that the calm was not too prolonged (as has happened before – when wind generation was < 1% of capacity).
Of course this scenario would not be relevant for solar power – and I am unsure how much it is subject to weather (10%?) and time of year and length of daylight (more important in more northerly locations).
Would this problem be lessened if the government allowed hybrid cars? If the grid demand was such that all power was needed (the windless sunless winter months usually) the cars would still be useful and provide storage.
The government clearly intend to tax and legislate petrol and diesel cars off the roads while they could offer flexible energy storage which the UK badly needs