Limiting carbon emissions is harder when you’re conserving water

Pacific Northwest National Lab

In the US, fully half of the water withdrawn from sources such as lakes and aquifers ends up being used for generating electricity. Most of that water is converted to steam, cooled, and returned to its original source. Even in those cases, however, losses during the cooling process reduce the total amount of water available.

The end result is that electricity generation ends up competing with other potential uses for the water. And in cases of severe drought, power generation may end up losing, reducing the amount of electricity we can generate. This situation is a problem given that climate change is expected to exacerbate droughts in a number of regions of the US.

To find out how much of a problem this can be, three MIT researchers have looked into the balance between water use and carbon emissions, using the Texas power grid as their test tube. Their model shows that taking carbon emissions into account is bad news for coal, but limiting water use essentially forces coal off the grid. While nuclear looks great for limiting carbon emissions, its heavy water requirements cut down on its role when both factors are considered.