New Hydrogen "Water Battery" Could Make Wind and Solar Greener

A new device that converts water to hydrogen gas could help solve an emerging carbon emissions dilemma for businesses and other electricity consumers. Companies want to be applauded for switching to wind or solar energy, but here in the US that choice is not necessarily as green as it could be. As long as coal and natural gas account for the lion's share of power generation in the US, companies that order up grid-supplied clean power may be unwittingly supporting a cushion of fossil fuels in the grid, too.

Part of the problem is that utilities are responding to the addition of wind and solar by adding new natural gas power plants, to smooth out supply and demand bumps. Grid stakeholders can also use energy storage to keep leveraging natural gas and coal into the grid. That's because they can store energy at night when rates are low, and then sell (or use) the low cost electricity during the day when peak demand grid prices kick in.

A Liquid Solution To The Carbon Emissions Problem

The good news is that the carbon emissions problem doesn't necessarily have to be in force forever. As more renewable energy enters the grid, the profile of natural gas and coal will keep shrinking.

So far natural gas has been the main driver pushing out coal. More recently, wind and solar are also beginning to gain an edge over both natural gas and coal (nuclear energy is a whole 'nother can of worms).

That's great, but it still dumps the issue of reliability onto the laps of utilities and grid operators.

Part of the solution is to manage demand. That can be complicated because it depends on behavior change, but solutions are already beginning to emerge. Some examples include "virtual power plant" technology that motivates consumers to change their habits. Incentivizing energy efficiency is another factor that could be ramped up.

Electric vehicles can also assume a larger role in their capacity as mobile energy storage units. Owners could be incentivized to charge up when demand is low, and even contribute their stored energy to help avoid reliability issues during peak demand periods.

That thing about EVs leads right back around to the energy storage problem. As the economy decarbonizes, the demand for energy storage will rise. Distributed solutions like EV batteries can pull some of the load, but energy insiders seem to agree that utility scale or bulk storage will also be needed far into the foreseeable future.

At this time, the consensus is that pumped hydropower is the only available strategy that makes economic sense for storing wind or solar energy in bulk.

Hydrogen gas is another water-based energy storage solution that Triple Pundit has been exploring at length, and that's where the new Stanford research comes in.

From water to hydrogen to energy storage

For those of you new to the topic, hydrogen is commonly used in food processing and other industries. It is also used for rockets and other space operations (NASA is a big fan) and it is increasingly used to power fuel cells, which generate electricity through a chemical reaction.

That fuel cell connection -- for forklifts, passenger cars and even semi trucks as well as stationary power sources -- means that in effect, hydrogen is an energy storage resource.

Hydrogen is cheap and abundant, but it doesn't come naturally. The main source of hydrogen today is natural gas. That's a problem of immense proportions in terms of local environmental impacts as well as greenhouse gas emissions.

Fortunately, natural gas does not have a lock on hydrogen production. Energy stakeholders are beginning to explore the use of biogas, and teams of researchers and industrial partners around the globe have been racing to develop technology that uses an electrical current to "split" hydrogen from water.

Ideally, that electricity would be generated by wind, solar or other renewables. The result is renewable hydrogen.

Finally, low-cost hydrogen energy storage

Water-splitting is a proven technology. The challenge is to make it more efficient and scale it up for bulk energy storage, while making it less expensive.

The Stanford team tackled the challenge head on. As reported in the latest issue of the journal Nature Energy, they developed a new water based energy storage device that can be recharged numerous times to generate hydrogen gas.

So far they have demonstrated a prototype-scale model that can bubble off hydrogen gas when exposed to an electrical current. Once that reaction is depleted, the water battery can be recharged to start the process all over again.

The research team deployed a type of salt called manganese sulfate to do the job. It fulfills the requirements of inexpensiveness and abundance, and it is already a familiar substance in commercial use today.

The salt dissolves in water when the battery is charging up, which leaves particles of manganese dioxide on the electrodes (the electrodes are the parts of the battery that accept and discharge an electrical current).

When that reaction is depleted, the particles re-combine with water to reform back into manganese sulfate and the process can start all over again. In the new study, the team reported that the prototype successfully recharged 10,000 times.

One hitch is that the prototype includes a platinum catalyst to kickstart the chemical reaction. The high cost of platinum prevents its use for bulk scale energy storage.

On the plus side, now that the Stanford team has demonstrated a low cost, rechargeable hydrogen production system, they can focus on incorporating a less pricey catalyst.

They already have several candidates in mind that would come in under the $100 per kilowatt-hour mark. That's the goal set by the Department for commercially feasible bulk energy storage aimed at maximizing wind and solar resources.

The next step is to test the system in real-world grid storage scenarios, so stay tuned for more on that.

For more details, check out the study, "A manganese–hydrogen battery with potential for grid-scale energy storage" in Nature Energy.

And for the record, the study was funded by the US Department of Energy so let's have a group hug for taxpayers and a shoutout to the Stanford research team of senior author Yi Cui and co-authors Guodong Li, Hongxia Wang, Jiayu Wan, Lei Liao, Guangxu Chen, Jiangyan Wang, Hao Zhang, Zheng Liang, Yuzhang Li and Allen Pei.

Image (cropped): US Department of Energy.