 Is microwaved candle wax the fuel of the future? An international team of researchers has shown that sprinkling paraffin wax with carbon and metal particles and heating the mixture in a microwave oven can produce hydrogen gas. The new recipe could lead to a cleaner, cheaper and more efficient way of fueling cars and devices that run on hydrogen. Hydrogen is one of the most promising alternatives to fossil fuels. When compressed, hydrogen has more than triple the energy density, and converting hydrogen to electricity using fuel cells generates only one major byproduct, water. Hydrogen breakdown is a relatively clean and safe process, but hydrogen storage is not. Many materials that can store and release hydrogen, such as metallic hydrides and rechargeable organic liquids, are highly reactive, creating a significant risk of fire or even explosion. A common material rich in hydrogen is wax. When heated, the long hydrocarbon chains that make up waxes are broken down. Some hydrogen and carbon molecules are even vaporized. But because numerous competing reactions are set off by heating, pure hydrogen gas molecules make up a very small fraction of the reaction products. Metal catalyst particles can tilt the chemical balance in favor of hydrogen formation, but a lot of the thermal energy still goes into unwanted reactions. To address this selectivity problem, the researchers turn to a familiar kitchen science phenomenon, heating metal in a microwave. Using microwave radiation, the team was able to generate energy hotspots near tiny ruthenium particles embedded in a mixture of carbon and paraffin wax. Tests showed that the formation of hydrogen gas, catalyzed by the ruthenium, greatly outpaced the formation of any other molecule. More work is needed to scale this microwave-based approach up and provide enough hydrogen to power systems as large as a car. But already, this discovery offers researchers a promising new way of generating hydrogen gas. Ultimately, this common material might do for the hydrogen economy what it did for the candle-making industry, provide a much cheaper, cleaner, and more reliable fuel than current alternatives.