By Kate Abnett BRUSSELS (Reuters) – Spain and Portugal next week will start subsidising fossil fuel power plants’ generation costs, under a 8.4 billion euro ($9 billion) scheme designed to pull down electricity prices for consumers and industry. European governments are struggling to manage surging gas and power prices, pushed higher by Russia’s invasion of Ukraine. Both countries plan to massively expand renewable energy generation this decade, to cut reliance on fossil fuels – but in the short term are seeking ways to curb the cost of electricity, which is often set by gas generators. Spain …