Water Is Key to Successful Operation
Defining the Problem for Emerging Tech—Hydrogen Production
The emerging potential of hydrogen as a low-carbon fuel as a possible fossil fuel alternative is a good example of the overlap between energy production and water use. Hydrogen is both energy-dense and carbon-free, making it an attractive baseload option for electricity generators and a fuel replacement for heavy industry and transportation. Electrolysis, a process used to make hydrogen fuel, uses electricity to split water into hydrogen and oxygen. This could be a climate-friendly approach to its production if the electricity is sourced from renewable or nuclear generators.
However, electrolyzers—the equipment used in this process—have high cooling needs, with larger installations incorporating utility-scale cooling towers requiring water resources exceeding those needed to directly produce the hydrogen. In fact, these cooling demands could reach two-thirds of a facility’s overall water consumption. Cooling water not lost through evaporation can be reintroduced to freshwater supplies but will typically need treatment to handle concentrated saline and other contaminants first. It also might be too warm to directly replenish supplies at its source because of concerns regarding fish and plant life, and it might also add to trends of increasing temperature and salinity in local water bodies.
Carbon Capture and Sequestration
Capturing CO2 from fossil fuel-based power plants and sequestering it in the ground could allow electricity companies (as well as other industries such as cement manufacturing) to continue to use existing generation technologies while significantly reducing greenhouse gas emissions. Here, too, though, the most commercially available carbon capture process—post-combustion capture—is highly water-intensive. Cooling loads exist at four steps in the process for the amine-based, post-combustion capture system, which is the most commercially available process today.
CO2 sequestration, which is not yet utilized at a large scale, also could have significant water consequences—for example, through the potential need to extract water from highly saline underground aquifers to provide room for the stored CO2. That water would require treatment before it could be returned to other aquifers or otherwise reused.
CARBON CAPTURE AND SEQUESTRATION
HYDROGEN PRODUCTION