German power, gas grids co-operate on storage plans up to 2030

* Companies plan to build big power-to-gas plants

* Aim to help cope with expanding renewable power volumes

* Supervisory bodies must agree as customers pay bill

FRANKFURT, June 20 (Reuters) - Major German power and gas grid firms Amprion and Open Grid Europe (OGE) unveiled plans on Wednesday to jointly build large power-to-gas (ptg) plants next decade, seeking to harness a new technology to help store and transport renewable energy.

The two said they had presented the proposals to Germany’s energy regulator, the Federal Network Agency, with a view to securing permission for plans that stretch to 2030, a period when Germany is phasing in tougher climate protection goals.

“We are looking at 50 to 100 megawatt (MW) size ptg plants, potentially in Lower Saxony or northern North-Rhine Westphalia state,” Amprion board member Hans-Juergen Brick said by phone after a press conference in Berlin.

“A first plant could go up in 2022 or early 2023,” he added.

Ptg technology offers a way to solve the storage problem of volatile electricity output from wind and sunshine by running it through water to split it into oxygen and hydrogen, which can be used as a transport fuel or fed into gas grids.

Grids must deploy new strategies to cope with the government’s latest targets to nearly double the share of wind and solar power to 65 percent of electricity generation by 2030.

So far, ptg plants have only been up to 6 MW in size, at non-commercial test locations.

“While government plans say they want 2,000 - 3,000 MW of power storage by 2030, we won’t get far with a maximum 6 MW per plant,” Brick said.

The ptg plants would complement thousands of kilometres of new north to south cables also planned by Amprion and its peers to come online by 2025, to accompany the boom in green power production.

But the lines have been delayed by public opposition.

Amprion’s annual report showed that of Germany’s targeted 153 gigawatts (GW) of installed renewable capacity by 2030, 60 percent has already been put in.

But only 11 percent of a total 7,900 km of new power lines designated to accompany the new capacity has been built.

This has resulted in northern Germany often wasting excess wind power, while the industrial south risks shortfalls.

The resulting costs for redispatch - major intervention measures on the power grid by engineers - in 2017 rose by 75 percent to 1.4 billion euros ($1.6 billion).

This is contentious as consumers must share grid costs as part of their bills.

$1 = 0.8651 euros Reporting by Vera Eckert; editing by Mark Potter