Coal-fired power plants could fall under the European Union's plan to cap energy producers' profits to raise cash to reduce rising energy bills, Reuters reported, citing a draft document.

The European Commission last week proposed a package of emergency measures to curb energy prices, including taxes on excess profits from energy companies that governments could use to protect businesses and citizens from sky-high energy bills this winter.

Diplomats from EU countries are discussing proposals and trying to find deals that everyone will be ready to approve at the Sept. 30 meeting of EU energy ministers.

A draft of the countries' latest negotiating document, seen by Reuters, would allow countries to subject coal-fired power plants to an EU-planned revenue cap on electricity producers.

Member states may allow the regulator to maintain or set a certain limit on market revenues derived from the sale of electricity produced from hard coal, the draft said, which could still be amended before the Sept. 30 meeting.

The commission proposed a revenue cap of 180 euros ($179.64) per megawatt hour for electricity producers with the cheapest operating costs, including wind, solar and nuclear power plants, because those plants could profit most from a surge in electricity prices.

Coal-fired power plants were excluded because the Commission said their operating costs exceed 180 euros/MWh, so a revenue cap could make them unprofitable.

But EU countries plan to get around this by capping the revenues of coal-fired power plants at a higher level if their operating costs exceed 180 euros/MWh, according to a document drafted by the Czech Republic, which holds the EU presidency.

Countries could also set a higher revenue ceiling for other plants with higher operating costs to ensure that they can continue to operate and earn a reasonable rate of return.

EU member states are also considering the EU's proposed windfall profits levy on fossil fuel companies.