Sustainably minded folks get excited about hydrogen because when you burn it for energy, the only byproduct or emissions is water. It’s super clean to use—it just isn’t necessarily super clean to make. While hydrogen occurs in abundance on our planet, there’s no simple way to capture it, so we’re left with having to manufacture it. This can be done through one of several proven but energy intensive processes. Today, these processes are typically powered by fossil fuels, which negates the clean powering properties of hydrogen itself.
Fortunately, the irresistible allure of creating hydrogen safely, efficiently, and sustainably has spawned innovation on several fronts, and with the U.S.’s Inflation Reduction Act of 2022 (IRA) the innovators have been put on high alert. Why? The Clean Hydrogen Production Tax Credit creates a new 10-year incentive for clean hydrogen production. There’s a tax credit of up to $3.00/kilogram and innovators can also claim up to a 30% investment tax credit, plus they can stack the credit with the renewable energy production tax credit and zero-emission nuclear credit.
But which of these innovators get to claim these credits will depend on what counts as clean hydrogen and that has yet to be determined by the U.S. Treasury Department. Using fossil fuels to create ‘clean’ hydrogen hasn’t been ruled out yet, so there’s a grey area... and a turquoise and a yellow one too.
The hydrogen color rainbow
There’s a color-coding system ascribed to how hydrogen is produced. Green hydrogen is produced using an electrolyzer powered by renewables while blue uses a steam reforming process powered by natural gas. While there’s no debate that green hydrogen is clean hydrogen, the consensus on blue hydrogen is less clear. Although blue hydrogen uses natural gas in its process, it also includes carbon capture and storage to sequester carbon, potentially giving it a ‘clean’ hydrogen designation.
The following table summarizes the color-coding system and related processes.
When it comes to achieving our clean energy goals, hydrogen experts and advocates are split on the best path forward for increasing the U.S.’ domestic hydrogen production capacity. There’s a chicken-and-egg problem with regards to the supply and demand of hydrogen: there’s not enough demand for it because cheaper fuel alternatives already exist, and the only way hydrogen will get cheaper is if it’s produced at scale. The U.S. government is actively working on the scale part of the equation—it selected seven regional clean hydrogen hubs which will receive $7 billion in Bipartisan Infrastructure Law funding to accelerate the domestic market for low-cost, clean hydrogen. Not all this funding is going exclusively to electrolyzer-produced hydrogen, but among advocates for a truly clean production method, electrolysis is where it’s at.
You can generate hydrogen via electrolysis, so if the electricity is provided by renewables, then the hydrogen is clean from the start. The tricky thing with electrolysis is that it’s a precision process (after all, we are splitting molecules) and that precision process requires a steady, consistent power stream. Steady and consistent are not what solar and wind energy are known for, which is why creating hydrogen using renewable sources is still in its infancy.
Currently two electrolyzer technologies are commercially available and have power requirements that can be met by renewables: alkaline and proton exchange membrane (PEM). Of the two, PEM electrolyzers tend to be favored due to their ability to handle power supply fluctuations. But the membrane and other components PEM electrolyzers rely on consist of expensive materials that need to be maintained and replaced regularly. This drives up the cost of PEM electrolyzers.
On the other hand, alkaline water electrolyzers are believed to have a longer lifespan and have lower annual maintenance costs compared to PEM electrolyzers. It would seem that if the power fluctuation issue could be resolved, alkaline tech electrolyzers would be the more cost-efficient solution. So how big a deal is the ability to handle power fluctuations? First let’s look at what’s at stake.
Remember, we’re splitting molecules, so it’s a pretty big deal. The power keeps the ion flow going, driving the split OH- ions across the electrolyzer cell and pushing the hydrogen and oxygen out of it. If the power stops, the ion flow stops and the hydrogen and oxygen that’s hanging out, not going anywhere, can form bubbles. Bubbles are bad because they can block the current flow once the power comes back on and that can cause problems in that the increased power resistance or current density can degrade the catalysts. But even worse than that is that the bubbly mixture of hydrogen and oxygen can get explosive. Electrolyzers have built-in safety systems to prevent such explosions, which means they shut down when such conditions are detected. But production shutdowns are never good news.
Given the risks, stabilizing power delivery from the renewable sources is an absolute must if alkaline electrolyzers are to succeed at green hydrogen production and that’s where precision control comes in to play. Fortunately, there’s a solution for that: put all the renewables on a microgrid and have a precision microgrid controller handle the power flow.
Setting up a hydrogen production facility microgrid
Oil and gas companies are typically the entities who have taken charge of building these kinds of facilities. By their nature, they haven’t had to think too hard on how to power their processes and they haven’t had need for microgrids. But once fossil fuels are taken out of the mix, the formula for creating a stable power supply changes from a singular power source with a backup generator to multiple renewable power sources with a backup battery. And for that configuration, you need a microgrid.
People think of microgrids in terms of backup power for when the main grid goes down, which isn’t wrong, but a microgrid is also just a mini grid that has all its power sources and batteries coordinated to provide a stable, steady source of power. In the case of green hydrogen, the microgrid doesn’t have to be grid-connected since it would source all its power from the renewables. Coordination is key and that’s what the precision microgrid controller is for. The controller’s job in this case is to:
- Ingest weather forecasts to predict generation capacity
- Track and manage renewable generation production in real time
- Manage the battery storage to charge/discharge appropriately to smooth out any renewable intermittency
- Guarantee delivery of a set amount of power to the electrolyzer for stable continuous production
- Manage power at the point-of-interconnection (if grid-connected) for power import/export as appropriate
This is the model that is being implemented in Western Australia for the Yuri Renewable Hydrogen to Ammonia Project.
Yuri: one of the world’s first industrial-scale renewable hydrogen projects
Scheduled for completion in 2024, the Yuri facility includes an 18-megawatt solar power plant, 8-megawatt battery energy storage system (BESS), and 10-megawatt electrolyzer which will produce up to 640 tons of green hydrogen per year. Notably, the Yuri project will use an alkaline electrolyzer, which as mentioned earlier, will require precise power flow to ensure consistent hydrogen production. PXiSE Energy Solutions is providing its Microgrid Controller, which relies on a predictive analytics engine to forecast and dispatch the solar and battery assets and independently controls real and reactive power in real time to ensure a stable power flow to the electrolyzer. Proven in other multi-renewable asset configurations, PXiSE is confident its high-speed, precision controls are up to the exacting task of hydrogen production.
As one of the world’s first industrial-scale renewable hydrogen projects, the world’s eyes are on Yuri to forge the path ahead for green hydrogen production.