Bangladesh, Sept. 24 -- Europe's latest energy shock is forcing an uncomfortable question onto the European Union's policy agenda: how much should governments be willing to relax environmental and fuel-quality rules when consumers are facing record prices and supplies are tightening?

French President Emmanuel Macron has put that question directly to European Commission President Ursula von der Leyen. In a letter sent on September 18, Macron called for temporary flexibility in EU fuel-quality requirements, arguing that European refineries could increase diesel and kerosene output by roughly 5% to 20%, depending on the refinery and the measures adopted. He has also proposed allowing wider use of B10 diesel, which contains up to 10% biodie...