The Iran-Ukraine war has disrupted the debate on the global energy system, with Brent crude prices dropping from $119 per barrel to around $90 per barrel. This is a reminder that fossil fuels like renewables can be unreliable and volatile, and that securing domestic energy supply is crucial. The rise of the U.S. as the world's top oil and gas producer, powered by the shale revolution, has also influenced the debate about climate change and access to cheap, reliable energy. The price tag on building new renewable power systems is daunting, but it makes sense for governments to consider alternatives.