BRUSSELS - Adapting Europe's energy grid to a system largely run on renewable power will cost €584 billion between now and 2030, according to a leaked EU Commission document seen by news agency Reuters.

The commission is set to publish an action plan to build smart grids able to respond faster to intermittent local-supply fluctuations associated with wind and solar power.

While an EU ceiling on revenues from renewables is aimed at redirecting excess profits from low-cost electricity generation back to consumers, analysts and industry groups are now arguing that such measures are both risky — and come at a bad time.

As part of its emergency plan to tackle high energy prices, the European Commission proposed to temporarily cap at €180 per megawatt-hour (MWh) the price at which low-carbon electricity companies sell power.