Increasing power demand to cool homes in Spain is putting pressure on energy prices after the country’s grid boosted its reliance on gas generation in the wake of a massive blackout.

Spanish grid operator Redeia blamed power plants for the massive blackout that affected the Iberian peninsula in April, as it disputed a government report that said its failure to calculate the correct energy mix was a key factor.

The Spanish government has said that the national grid operator and private power generation companies were to blame for an energy blackout that caused widespread chaos in Spain and Portugal earlier this year.