5 New Sustainable Sources for Green Hydrogen

Green hydrogen could be a powerful driver of the global energy transition. Rather than extracting hydrogen from natural gas or gasified coal, the green hydrogen industry deploys electrolysis systems that “split” water into hydrogen and oxygen with an electrical current.

Assuming the electricity running the electrolysis equipment comes from wind, solar or other renewable resources, the result is a more sustainable source of hydrogen for zero-emission fuel cell vehicles. Green hydrogen can also shrink the carbon footprint of other hydrogen-dependent sectors, including the global chemicals industry, food systems, refining and steelmaking, among others.

The downside? Electrolysis systems need water — and plenty of it. It is commonly cited that it takes 9 liters of water to produce 1 kilogram of hydrogen through electrolysis, though the Rocky Mountain Institute suggests a total of 20 to 30 liters per kilogram is more accurate to account for water purification and cooling.

That sounds like a lot, but relative to conventional hydrogen systems, it isn't. Hydrogen systems based on fossil fuels require 20 to 40 liters of water per kilogram of hydrogen, according to the Rocky Mountain Institute. 

Still, with global freshwater supplies at substantial risk already, green hydrogen stakeholders have an opportunity to make a real difference. Instead of using clean, pure freshwater for electrolysis, they can use impure sources.

That sounds easy enough, but the devil is in the details. Impurities in water can quickly foul the delicate membranes in conventional electrolysis systems. New, more affordable pre-treatment systems are beginning to solve that problem, and innovators are developing hardier systems that can operate directly on impure water. Here are five emerging water-for-hydrogen developments to watch in the U.S. and around the world. 

1. Minnesota: Putting municipal wastewater to work

Water resource managers are adopting the phrase “water resource recovery facility” (or WRRF) as a more helpful and accurate description of what goes on at a wastewater treatment plant. The choice is timely, considering that WRRFs could form a practically limitless source of impure water for electrolysis. 

One showcase project is taking place in the city of St. Cloud, Minnesota, which is moving forward with plans to add a new electrolyzer system to its WRRF. The project includes substantial inter-agency partnerships and $3.6 million grant from the U.S. Department of Energy.

Once complete, the project will offset the fossil fuels that typically power the wastewater treatment process. The electrolyzers will run on renewable energy and produce oxygen as a byproduct, which will be used for the plant's aeration systems. The partners are also looking to support a fleet of hydrogen fuel cell buses with green hydrogen from the new electrolysis system.

2. Sweden: Seawater with an extra green twist

The oceans are another virtually infinite source of impure water for electrolysis. Researchers and innovators are drawing economical pathways for producing hydrogen from seawater, and offshore wind developers are already incorporating offshore green hydrogen production into their plans. 

One particularly interesting offshore project was proposed as part of a gigantic new wind farm off the southern coast of Sweden in the Baltic Sea. Called Neptunus, the wind farm project is a partnership between the renewable energy firm OX2 and the investments branch of Ingka Group, known as the leading franchisee of the iconic Swedish home furnishing company Ikea. 

In addition to feeding Europe’s growing demand for wind energy and green hydrogen, the partners proposed injecting oxygen from the electrolysis system into the Baltic Sea to help restore parts that are designated “dead zones” due to depleted oxygen levels.

3. Wales: Water from factories and rooftops, too

A project in Wales illustrates how green hydrogen production can work in concert with local industries and even the local weather. The utility Wales & West partnered with the global firm Hydrostar to explore the use of industrial wastewater for electrolysis.

The partners are investigating three membrane-free electrolyzer prototypes, which can be tailored to operate on specific kinds of industrial waste. These systems could be located at manufacturing sites that produce large amounts of wastewater, including textiles, electronic goods and processed foods.

In a nod to Wales’ rainy weather, the project also covers rainwater harvested from rooftops and storm runoff, which contains a variety of impurities.

4. Scotland: Water from spirits

In another project that makes use of local resources, a research team at Heriot-Watt University in Scotland uncovered a way to reuse the wastewater from distilleries for green hydrogen production. Every liter of malt whiskey generates about 10 liters of residue, adding up to an estimated 1 billion gallons of wastewater from the global whiskey sector each year, according to the researchers. 

Their solution is an affordable pre-treatment step that deploys nanoscale particles of nickel selenide, a semi-conducting material. Their initial findings suggest that the pre-treatment does not interfere with the efficiency of the electrolysis system and may even result in a slight increase in efficiency.

5. Oregon and California: Beyond electrolyzers 

Electrolysis is not the only way to produce hydrogen from water. Another method consists of an “artificial leaf” approach in which hydrogen is released through a chemical reaction started by sunlight, with the help of a catalyst substance that speeds up the process. 

At Oregon State University, scientists partnered with researchers from the tech company HP to develop a catalyst that can rid water of pollution from herbicides while producing hydrogen, too. 

Specifically, the catalyst is designed to tackle herbicides containing glyphosate, sold under the trade name Roundup. The leaching of glyphosate into soil and groundwater is a significant concern because crops only absorb a small amount of it. "We are showing that through photocatalysis, it is possible to produce a renewable fuel while removing organic pollutants, or converting them into useful products,” lead researcher Kyriakos Stylianou said of the findings.  

Another green hydrogen project underway in California aims to produce hydrogen from biomass instead of water. Set to open next year, the new biomass facility will use brush from forests, helping to reduce the risk of wildfires, as well as agricultural waste that would typically be burned or buried. Instead, the waste will be rendered into green hydrogen and biochar, which is gaining traction as an important carbon sequestration agent. Hydrogen from the new facility will be marketed as a replacement for diesel fuel at the Port of Los Angeles.

The bottom line: Creativity keeps green hydrogen on the cutting edge

Altogether, these initial projects illustrate how the green hydrogen industry could help resolve environmental challenges beyond simply replacing fossil resources with renewable ones. That should be all the more reason to adopt them into mainstream practice heading into 2024 and beyond.