Battery-grid technology

Britain’s most ambitious smart grid project is being built on a housing estate in Leighton Buzzard. UK Power Networks (UKPN) is installing a giant battery farm that will supply electricity to local users at peak times. Around 240 tonnes of lithium-ion batteries are being installed in a specially designed building raised 2 metres above the ground to protect it from flooding by the nearby river.

The demonstration project, which is scheduled to begin operating in September. Once it is fully operational, Leighton Buzzard will have the capacity to discharge up to 10 megawatt-hours (MWh) of power into the local distribution network at a rate of up to 6 megawatts (MW), enough for 6,000 homes.

The aim is to test the technical and financial feasibility of using storage to reinforce the power grid and help meet peak loads as an alternative to the conventional approach of installing more substations and overhead power lines.

STORAGE SOLUTION

The traditional model is being blown apart by the government’s ambitious targets to combat climate change by electrification and decarbonisation. Over the next 30 years, Britain will need vastly more generation and transmission capacity and the power supply will become much more variable and unpredictable.

The government plans to replace gasoline and diesel-powered cars with electric vehicles and gas-fired home boilers with electric heaters which implies a six-fold increase in peak demand from the current 60,000 MW to as much as 370,000 MW by 2050.

At the same time, government plans to decarbonise the system by increasing the amount generated from renewables like wind and solar imply much more variability in supply because they cannot be scheduled in the same way as coal and gas-fired power stations.

LOAD SHIFT OR STORE?

In future, as consumption grows and supply becomes more unpredictable, it will be even harder and more expensive to meet peak demand. Policymakers and the industry are therefore considering how to adapt the traditional generation and distribution model.

One option is to smooth out the peak in consumption and make demand more flexible by introducing smart meters and time of use tariffs. Every household in Britain will have a smart meter installed by 2020. Smart meters will measure the amount of electricity consumed in every half-hour period.

In theory, once smart meters have been installed, suppliers could introduce higher tariffs for peak periods (generally 4 pm to 8 pm on winter evenings) to encourage customers to shift consumption to other times of day when demand is lower, which would make more efficient use of generation and transmission assets.

The other main option is to introduce more storage on the network. Storage units would absorb excess power overnight and when wind and solar production is especially high, then discharge it at peak times, smoothing the demand profile.

Britain already has some limited electricity storage in the form of pump-hydro. The problem with pump-storage is that it is enormously expensive and suitable sites are rare. Batteries are cheaper and can be scaled to any required size. Storage batteries can be installed at any scale – from an individual home to a street, or even directly onto the distribution and transmission networks at the substation level. But batteries are still more expensive than conventional network reinforcement. In general, distribution companies find it cheaper to install extra lines and substations to meet peak demand.

UNLOCKING REVENUE

UKPN puts the capital cost of the battery scheme at Leighton Buzzard at 11.2 million pounds ($18.82 million), compared with 6.2 million pounds for conventional reinforcement, with an extra overhead power line and another transformer.

Battery enthusiasts also hope their storage units can earn extra revenues by providing a variety of additional services to the grid, for which they would get paid.

There are still some problems to overcome before battery farms can start unlocking all these extra revenue streams. Britain’s regulators consider electricity storage to be a form of generation. Under current rules, distribution network operators like UKPN are not meant to own “generation” assets directly, so it has to be organised through independent third parties.

Giant battery farms still seem outlandish. But storage will probably play a much bigger role in the smart electricity grid of the future. See link for full article

Battery FarmBattery-grid technology

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