How Clean Is Green Hydrogen?

Written By Teacher: Elizabeth Ward

My name is Elizabeth Ward. I am a former Early Childhood, Elementary, and English as a Foreign Language educator. I have taught third grade Science and Social Studies as well as Kindergarten in both urban and rural Oklahoma public schools. I taught online EFL to students of all ages in China for four years. I also have experience in curriculum development and content design for teachers in the physical and digital classroom. As a former teacher I have a passion for supporting teachers and making their jobs easier. I currently live in the greater Houston area with my husband and four dogs. 

Hydrogen is often promoted as a clean energy source, but its environmental impact depends on how it is produced. While "green hydrogen" is made using renewable energy, other forms rely on fossil fuels, raising questions about sustainability. Exploring this topic helps students evaluate different energy sources, technological advancements, and the challenges of scaling up green hydrogen. Encourage conversation and learning about renewable energy with resources such as this Renewable Energy Student Lab for older students and Renewable Energy lesson plan for elementary students.

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

Hydrogen is often held up as a potential clean fuel of the future, because it can be burned like oil or gas but releases no climate-warming carbon dioxide (CO2)—only water. But while hydrogen is the most abundant element in the universe, there isn’t an easy-to-tap source of pure hydrogen available on Earth. To use it, society must manufacture it.

That manufacturing process can release climate pollution, so how "clean" hydrogen is depends on how it’s produced.

The best option for the climate, says Emre Gençer, a principal research scientist at the MIT Energy Initiative, is so-called "green" hydrogen. (Which, like all hydrogen, is actually colorless.) To make green hydrogen, producers use electricity from a renewable source like wind or solar to split water molecules, removing hydrogen from oxygen and taking the H out of H2O.

This process can emit 1 kilogram or less of CO2 per kilogram of hydrogen produced, depending on the supply chain of the renewable electricity and the overall efficiency of the process. Currently, for instance, producing green hydrogen using wind energy is a bit cleaner than using solar energy, says Gençer. That’s because manufacturing solar equipment takes more energy, and wind energy installations produce electricity at their maximum output more often than solar projects of the same size.