Are Blue and Green Hydrogen Too Water Intensive to Be Sustainable?

Despite continued outcry from environmental justice advocates and frontline communities, the US continues to lead the world on federal spending for hydrogen, a fuel whose dangers threaten to outweigh any benefits it can provide to the clean energy transition. The Biden Administration continues to pour billions of dollars into large-scale projects like the Regional Hydrogen Hubs, despite ongoing research revealing the serious environmental and public health impacts hydrogen can have. One such issue that is often overlooked is the devastating consequences blue and green hydrogen production can have on the water supply. This is particularly concerning since, at a time when groundwater tables are rapidly declining globally, over half of the blue and green hydrogen production capacity planned in the US is in water stressed regions.

Why is Hydrogen So Water Intensive?

Clean Energy Group recently released two fact sheets (available here and here) outlining why creating blue and green hydrogen can be so detrimental to local water tables, and how certain end-uses can worsen those impacts. To understand why hydrogen is so water intensive, you need to look at the production processes for each type of hydrogen.

Blue Hydrogen

Blue hydrogen refers to hydrogen produced from fossil fuels using a process called steam methane reforming (SMR), paired with carbon capture and storage (CCS) to capture some emissions from the process. Producing 1 kilogram of hydrogen via SMR requires 1.2 gallons of water to create the necessary steam. Once SMR is complete, the water used for steam has been transformed into hydrogen, which means none of it can be recycled. On top of this water consumption, CCS uses a lot of water for cooling. 92 percent of the total water needed to produce blue hydrogen is used for cooling, although some of this water can be recycled.

While these base numbers for water usage might not seem so bad, the issues become more apparent when you consider that the average blue hydrogen plant produces over 500,000 pounds of blue hydrogen a day. To produce that level of blue hydrogen, a plant would consume 1.9 million gallons of water a day from the water supply, and only recycle about 450,000 gallons of that water. And that’s just to make the blue hydrogen – if that hydrogen is then burned in a power plant, the power plant will need additional water for cooling. Power plants account for 40 percent of all water withdrawals in the US, and if those plants burn hydrogen, they will need even more water.

Green Hydrogen

Green hydrogen is often held up as the least harmful form of hydrogen production, because it refers to hydrogen produced via electrolysis, in which an electric current is run through water to separate out the hydrogen molecules. If that electric current is powered by renewable energy, then hydrogen is considered “green” or zero-carbon.  However, green hydrogen comes with its own set of harms. Unsurprisingly, electrolysis is very water intensive, consuming 2.6 gallons of water for every kilogram of water produced. And since that water has been broken down into hydrogen, none of it can be recycled. On top of that, electrolyzers require purified water. This requires taking roughly double the amount of water needed from a local water source, such as a municipal wastewater treatment plant, and then purifying it. Once the water has been run through the purification process, the “reject” water often contains a highly concentrated mix of impurities, making it difficult to recycle.

Green hydrogen production is still very expensive, so most green hydrogen production facilities are nowhere near the size of blue hydrogen plants. But because green hydrogen production uses so much water, the impact of even a mid-sized plant can be devastating to local water supplies over time. A green hydrogen plant producing 11,000 metric tons of hydrogen per year, like the one that just broke ground in Arizona, will consume 26.4 million gallons of water a year, none of which can be recycled. And once again, if that hydrogen is burned in a power plant, those water impacts will only be compounded.

Washing Away the Hype

While there may be some very limited use cases where zero-carbon green hydrogen makes sense, those need to be weighed against the many harms it poses. As climate change worsens already stressed water tables, pouring billions of federal dollars into propping up massive new sources for water demand is recklessly endangering the future of many communities across the country. Environmental justice groups in water stressed regions like New Mexico have already identified the threat that hydrogen poses – it’s clear that the government just doesn’t want to listen.