If the latest twist on renewable hydrogen works out, Idaho will be known for more than potatoes. A research team at the Idaho National Laboratory in Idaho Falls, Idaho has come up with a two-way device that deploys electricity to “split” hydrogen from steam when you need hydrogen, and deploys hydrogen to generate electricity when you need electricity. So, what could possibly go wrong?
Renewable Hydrogen From Steam, But Why?
Water-produced hydrogen is not a new technology. It’s based on electrolysis, which “splits” hydrogen from water using an electrical current. It’s not particularly “renewable” if the electricity is from a fossil power plant, but add wind or solar power an now you’re getting somewhere.
Renewable hydrogen is beginning to emerge as a marketable renewable fuel and energy storage medium for excess wind and solar power. The steam thing is a different kettle of fish.
The first question would be why create steam from water instead of just going straight to water for your renewable hydrogen. After all, it takes a lot of energy to make steam.
For the answer to that, consider how nuclear power plants operate. They operate most efficiently at maximum capacity, so they aren’t very good at ramping down (or up) to match demand patterns. That means a fair amount of excess or potential energy has to be shunted off. If it takes the form of steam, then renewable hydrogen presents an opportunity to store, use, or transport it.
Renewable Hydrogen From Steam
As the nation’s leading nuclear energy research institution, INL has been taking a look into the idea of squeezing more life out of the nation’s fleet of nuclear power plants.
The steam-to-hydrogen angle is an attractive one from the perspective of reclaiming energy that would otherwise go unused. The basic technology involves electrochemical cells, and there is already a class of cells that work on steam at high temperatures, called protonic ceramic electrochemical cells. The problem is that existing PCECs are too expensive for commercial use. They are designed with costly materials that can cope with heat up to 800 degrees centigrade, and those materials tend to degrade quickly.
Renewable Hydrogen + Perovskite
Here, let’s have the INL research team, spearheaded by senior engineer and scientist Dong Ding, explain it:
“…the large-scale deployment of PCECs still remains elusive by severe limitation on developing highly active and robust electrode due to sluggish electrode kinetic at intermediate temperatures and decayed lifetime of the material and interface, especially under high-steam concentration.”
To solve the problem, the research team took a holistic approach that involves a new material — an oxide of perovskite — and a meshlike structure that enables the cell to function efficiently at lower heat, say in the range of 400 to 600 degrees.
For those of you new to the topic, perovskites refers to a class of synthetic crystals based on the structure of natural perovskite, which researchers are super-excited about for its application to photovoltaic technology.
The new form of perovksite similarly exciting. Conventional high-temperature electrolysis involves an oxygen electrode, for conducting electrons and oxygen ions. With the oxide of perovskite, the new electrode can also conduct protons. That makes for a higher degree of efficiency under a lower degree of temperature.
“In this study, a triple conducting oxide of PrNi0.5Co0.5O3-δ perovskite is developed as an oxygen electrode, presenting superior electrochemical performance at 400~600 °C,” the team explains, adding that “The excellent electrocatalytic activity is attributed to the considerable proton conduction, as confirmed by hydrogen permeation experiment, remarkable hydration behavior and computations.”
Want more? Check out the study in the journal Nature Communications under the title, “Self-sustainable protonic ceramic electrochemical cells using a triple conducting electrode for hydrogen and power production” over the bylines of Hanping Ding, Wei Wu, Chao Jiang, Yong Ding, Wenjuan Bian, Boxun Hu, Prabhakar Singh, Christopher J. Orme, Lucun Wang, Yunya Zhang, and Dong Ding.
Onward & Upward For Energy Storage
The new INL renewable hydrogen device will be spinning around in the lab for a while before it’s ready for industrial use. If and when it finds space in the market, it won’t necessarily support the construction of new nuclear power plants, at least not here in the US.
An economical high-temperature electrolysis device could find a home at existing nuclear facilities as well as other industrial operations that produce excess steam, so there’s that. The idea would be to leverage hydrogen as an economical, long duration, bulk energy storage medium, which is something that the Energy Department is avidly pursuing for wind and solar.
Hydrogen has the additional advantage of being transportable, and there is a movement afoot to introduce renewable H2 into existing natural gas infrastructure.
Renewable hydrogen may not end up being the most economical solution overall, but it could beat out other solutions in regions where new transmission lines are cost-prohibitive. Here in the US, for example, New Hampshire and other northeastern states are looking at renewable H2 as a means of resolving transmission bottlenecks while introducing more wind and solar into the grid.
All things being equal, low cost hydrogen energy storage could also serve as a lifeline for fossil fuel power plants, but it sure looks like that ship has sailed.
