The transition from coal to natural gas is expected to significantly decrease carbon emissions. However, gas production poses its own environmental concerns. One of those is the problem of so-called “produced water”—large volumes of underground water with a lot of salts and minerals, that flow to the surface along with gas. This water must be somehow cleaned or otherwise disposed of. There are several processes available to perform this task, but most of them are expensive and quite inefficient. A new method developed at MIT could help solve the problem and produce clean water at relatively low cost. In the future it could also be used specifically at water purification plants, especially in developing countries.