Britain could have a 12-gigawatt battery market by 2021, according to a parliamentary policy group.

The paper was written by the U.K. Renewable Energy Association (REA) and an All-Party Parliamentary Group (APPG) on Energy Storage, an interest group made up of members of the House of Lords and House of Commons.

Hitting that 12-gigawatt target will require major policy support, however.

The figure assumes a scenario in which all the policies contained in the U.K. government’s July 2017 smart systems and flexibility plan are rolled out on schedule and in parallel with other reforms, including tax incentives. 

In practice, a medium deployment scenario of 8 gigawatts by 2021, up from 60 megawatts of battery storage today, is more plausible, concludes the position paper.

Many of the medium-scenario drivers are “already happening outside legislation,” said the paper’s lead analyst and editor, Frank Gordon of the REA. 

The REA and the APPG believe the biggest boost for electrical storage in the U.K. will come from renewable energy producers adding batteries to solar and wind projects, so they can earn extra revenues from capacity markets and arbitrage.

The position paper’s high deployment scenario assumes 40 percent of U.K. solar generation and 25 percent of wind could have battery storage attached to it by 2021, equaling a total of some 8 gigawatts of capacity.

The medium deployment scenario would see around 3 gigawatts of solar-connected and 2 gigawatts of wind-connected battery storage. Under a low deployment scenario, around 1 gigawatt would be installed, split evenly between solar and wind.

One of the market shifts favoring the co-location of storage is already underway. The U.K. Energy Networks Association, which represents network operators, recently pledged to overhaul the market for flexibility services. 

“The move will help reduce the cost of running the network to customers and provide new opportunities for businesses and communities to offer flexibility services to local network operators,” said the Association in a press release

The position paper is meant to encourage lawmakers to push energy storage as a new form of industrial policy.

“Today no one country holds a distinct lead internationally in energy storage research, development and deployment, but many are positioning for leadership,” the paper states. “Whoever wins the race will not have done so without creating a thriving domestic market first.”

However, the authors may have sacrificed technical rigor in their haste to appeal to politicians.

For example, the battery capacity forecasts were given in power rather than energy terms, partly because gigawatt-hour capacities were harder to calculate and partly because it would be easier for laypeople to understand gigawatts alone.

Elsewhere, the paper paints a rosy picture of the potential for industrial leadership in energy storage, glossing over the fact that the U.K. lags far behind countries such as China, Germany and the U.S. on this front.

For instance, it cites a Nissan battery factory as evidence that “recent investments in the U.K.’s electric vehicle supply chain and battery manufacturing capabilities are strong steps in the right direction,” despite the carmaker selling the business to a Chinese firm in August.

This may explain why the paper has been treated with caution by some observers. “Some of their statements appear to be a little bit confused,” one energy storage insider told GTM.

It follows a similarly blue-sky future electricity markets report in November, and comes as Britain ponders how to keep the lights on after it retires most of its coal-fired generation capacity and exits from the European Union.

In 2017, the country put millions of pounds into research and development initiatives, including the creation of a battery institute. “Energy storage is a bit of a government starlet at the moment,” said Gordon.