Green hydrogen is produced through renewable energy sources, such as solar or wind power. This is in contrast to traditional hydrogen, which is produced from fossil fuels. In 2020, according to Wikipedia, 95% of all hydrogen was produced from fossil fuels (natural gas, oil, and coal).
Obviously, if we want hydrogen to be a renewable source of energy, this will have to change.
Interest in green hydrogen is growing
There seems to be growing interest in green hydrogen, as you can see in Google Trends, for example. After a long period of stagnation, sometime early 2020 interest has gained momentum (to be fair though, this is still easily outmaneuvered by topics such as artificial intelligence):

Green hydrogen is great for making fertilizers, steel, chemicals, shipping–but not for powering cars
I know there are some big automotive companies still working on hydrogen cars. But I find Michael Liebreich’s analysis, The Clean Hydrogen Ladder, more compelling (among many other things, Michael Liebreich is the founder of Bloomberg New Energy Finance). I encourage you to read Michael’s analysis, where he explains why his Clean Hydrogen Ladder looks the way it does:

The Green Hydrogen Ladder compares various use cases for green hydrogen, in terms of how likely they are to work. As you can see, top use cases include making fertilizers, steel, chemicals–but not powering cars (H2 fuel cell cars are at the bottom of the ladder).
Why am I telling you about this? Because I think it’s useful to have some kind of framework for thinking about the topic more generally.
A 360° snapshot on green hydrogen, across ventures and R&D
So there is growing interest in green hydrogen, and some promising use cases as well. But what’s happening in terms of new venture and R&D?
In order to get a first useful approximation (not a comprehensive analysis by any means), I simply searched in Mergeflow for “green hydrogen”. Here is an overview snapshot of my results (you can click on the image to see the interactive snapshot):

First, let’s start with venture-funded companies.
Companies
Ohmium International
Ohmium makes electrolyzers. Electrolyzers are devices that use electricity to split water into its components, oxygen and hydrogen.
One thing that’s special about Ohmium’s electrolyzers is that they can be stacked. This provides flexibility and scalability.

In April 2022, Ohmium received $45M Series B from investors including Fenice Investment Group and Energy Transition Ventures.
Planetary Technologies
Planetary Technologies is a carbon removal company. Their Accelerated Carbon Transition Platform uses mine tailings (= waste minerals in certain mining processes) as a feedstock. From these mine tailings, the platform recovers battery metals like cobalt and nickel; and it also produces green hydrogen.

Planetary Technologies is an XPRIZE Carbon Removal award winner, and in March 2022, they raised $7.8M from Innovacorp, Apollo Projects, and other investors.
H2U Technologies
H2U Technologies makes catalysts for water electrolysis (water -> oxygen, hydrogen). Now, the problem with currently used catalysts is that they are made of expensive materials. The goal of H2U Technologies is to discover and make new kinds of catalysts that are less expensive.
In order to discover new catalyst candidate materials (or catalytic activity of materials), they are building a platform called Catalyst Discovery Engine.

In March 2022, H2U Technologies raised $11M Series A from Jericho Energy Ventures, Freeflow Ventures, VoLo Earth Ventures, and Hess Corporation.
Verdagy
Verdagy makes new kinds of electrolyzers that enable large volumes of hydrogen generation. According to their website, their electrolysis cells are the largest in the industry. The company operates a pilot plant in California where the approach is prototyped.

In February 2022, Verdagy raised $25M from TDK Ventures, BHP Ventures, Doral Energy Tech Ventures, Khosla Ventures, Orbia Ventures, Shell Ventures, and Temasek.
8minute Solar Energy
8minute Solar Energy is a solar energy and energy storage developer. So they are more on the “building energy projects” side than on the “developing new technologies” side. Of course, this is a blurry line.

8minute integrates solar energy generation and storage so that they can provide a complete solution for continuously delivering power. And while they do not say explicitly how their energy storage works, I assume that they have plans to use green hydrogen for this: In January 2022, 8minute raised $400M from EIG. And their press release says that they “look to expand into green hydrogen”.
Green hydrogen R&D
In the beginning I mentioned that interest in green hydrogen seems to be rising (the Google Trends chart above). And R&D activity seems to be increasing as well. For example, consider the number of science publications in the screenshot from Mergeflow below (click on the image to see it in full size):
It’s not my goal here to provide a comprehensive analysis; rather a jumping-off-board for you to explore the topic further.
I used Mergeflow’s network graph tool to display the co-author networks in green hydrogen publications. There are several bigger sub-networks. One such network is centered around Bilu Liu from Tsinghua University:

Here are two of his most recent publications:
Recent Advances in Design of Electrocatalysts for High-Current-Density Water Splitting
Another network involves a number of researchers mostly at the German Aerospace Center, specifically there at the Institute of Engineering Thermodynamics (click on the image to see it in full size):
Here are two recent publications from the network:
Two-step thermochemical electrolysis: An approach for green hydrogen production
Again, these are only a few jumping-off-points. If you want to explore more, you can sign up for our free 14-day trial of Mergeflow.