Europe’s biggest economy, Germany, is bracing for another summer of swings in energy demand and prices as the national weather service issues its first heat warning for the season for this week. Germany’s weather forecaster Deutscher Wetterdienst on Sunday issued the first heat warning for the year – “heat stress” – as temperatures are expected to exceed 32 degrees Celsius (89.6 F) in the early afternoon this week and nighttime temperatures will only see limited cooling. Humidity has also risen in many parts…