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Question

What is your opinion on using hydrogen as a power storage mechanism for renewable resources?

Jeremy LaPlace's picture
President NOVA Hydrogen Solutions

I am a founder of a startup that is utilizing hydrogen fuel cells and electrolysis to fix the shortcomings of solar panels.

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  • Jan 20, 2022
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I'm trying to get a feel for the market. What are people's thoughts about green hydrogen for residential energy storage? My company aims to store hydrogen at residents homes utilizing solar power or other renewables in the US. Right now,it's cost prohibitive except for off grid places that use diesel or large battery backups but the price is coming down quickly.

I would love up hear your thoughts on the subject.

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The current estimates for "green hydrogen" are $5/Kg.  The DOE goal is to try to get that down below $1/Kg, although it probably needs to get down to $0.50/Kg to compete effectively with natural gas.  The picture gets further complicated by location.  Rooftop solar in New England has an 11% capacity factor.  It is worse in the winter. Recently, in CT, we had night time temperatures in the single digits for several days with more forecast in the next week or two.  With daylight hours shortened due to it being winter time, sun position being low on the horizon, and partly cloudy conditions on most days, there is not enough power delivered by the solar panels to electrically heat the house 24/7 including the use of batteries.  Generating hydrogen locally will not produce enough hydrogen to get through a cold night, never mind several days of cloudy weather.  Of course, the hydrogen can be generated elsewhere and delivered to the home for energy storage at the home with sufficient capacity to overcome this, but I didn't get that impression from the brief description.

 

Hydrogen is being considered for energy storage for precisely the reasons that I mentioned (longer duration intermittency).  MIT studies have indicated that batteries by themselves will not likely be sufficient to handle multiple days without sunlight or wind.  They note that little or no wind can last for up to two weeks, while cloudy days can last for about 1 week.  During that time, batteries will be depleted and not able to recharge if there are no fossil fuels being used on the grid.  Current batteries can operate for up to 4 hours and are fairly expensive.  Therefore, multiple batteries would be needed along with the extra capacity needed to charge those batteries.  Fuel, on the other hand, can be generated separately and stored for long periods of time.  Thus, seasonal swings as well as shorter term needs can be addressed.  That is why storable fuels (like oil and coal) are so useful.

 

The other point to be made is that of costs coming down.  I am less certain of that, particularly in view of the inflation that we are now experiencing.  Of course, no one really knows what inflation will be next year or next decade.  However, raw materials costs, particularly copper and semiconductors, are going up substantially.  Shipping costs and labor costs are also increasing.  Solar panels only represent 10 - 15% of the cost of an installation.  The disinflation that we have seen for the past 40 years may, in fact, be over.  That does not bode well for the assumption that costs will continue to come down.  They might, on a relative basis, but, then again, they might not.  A lot more work needs to be done.

 

Hydrogen will likely have its place, but it is not the "silver bullet".  A combination of technologies including nuclear, renewables, fossil fuels with CCS, improved efficiency, batteries, and others yet to be developed will be needed.

Jeremy LaPlace's picture
Jeremy LaPlace on Feb 2, 2022

I should specify that we would be providing seasonal power. Not short term. The system I have designed is a combination of super capacitors, battery banks and hydrogen. The SC and Li-Ion provide the short term day to day help, the H2 provides the seasonal power during winter time. It is modeled heavily after Mike Strizki of New Jersey Hydrogen House. There is a few key differences but largely the same.

The others who have responded so far are all correct. In addition, consider that unless the grid is saturated with renewable electricity, using generation that could be fed into the grid for hydrogen production will require fossil fueled generators to produce the shortfall. 

For energy storage, green hydrogen has a round-trip energy efficiency of about 40%. 2.5 kWh in for every kWh out. Pretty bad. Lithium-ion batteries, by contrast, can manage 90 - 95%. That's more than twice as much energy out for the same energy in. The only theoretical advantage that hydrogen can offer is the ability to expand energy storage capacity by expanding the hydrogen storage tanks. But hydrogen storage tanks are not cheap. Despite focused efforts over many years to develop something better, the best we can do is the carbon fiber-wound high pressure composite tanks that Toyota developed for their hydrogen fuel cell vehicles. With hydrogen at 2000 psi, they're able to store up to 5.5% of their mass in hydrogen. And there's no scaling advantage. So unless you're looking at some really major breakthroughs that have eluded everyone else, I'm sorry to have to advise you to forget it. Your product won't be competitive.

Bob Meinetz's picture
Bob Meinetz on Jan 22, 2022

"For energy storage, green hydrogen has a round-trip energy efficiency of about 40%."

Is that including ~15% of energy lost when compressing it?

GM's testing site for Chevrolet Equinox FCVs used to be about a mile from my home, and one day I was in a local Pep Boys when a GM tech pulled up in an Equinox. So I took the opportunity to press him for some real-world info on performance.

"The Equinox has two tanks underneath that run the length of the vehicle," he said. "A 'full tank', in comparison to a gasoline-powered car, is filled with hydrogen compressed to about 10,000 psi."
When I asked him whether the Equinox could really deliver the 250-mile range GM was promising, he smiled. "Nahh, they're working to improve efficiency, but I drive these things every day. Maximum range is about 80 miles."

So unless Toyota has discovered some magical new fuel cell technology for their FCVs, H2 stored at 2,000 psi might get a driver from his home to the refilling station and back.
 

Roger Arnold's picture
Roger Arnold on Jan 29, 2022

The short answer is no, the 40% estimate for round trip efficiency doesn't include allowance for energy needed to compress the hydrogen for storage. But it's a rough number anyway. It can vary by a few percentage points depending on a variety of factors. PEM electrolysis cells, for example, can evolve hydrogen under a reasonably high pressure to begin with, so that less energy is needed to complete the compression for storage in high pressure tanks. Advanced technology for AC - DC - AC power conversion can raise the efficiency by a couple of percent, while operation at high current densities for higher productivity can lower efficiency substantially. I've seen 35% used as the figure for round trip efficiency, and I've also seen claims for 45% or even higher in the future. But 40% is a good round number.

 

I misstated that 2000 PSI gave 5.5% hydrogen by mass. Should have been 10,000 PSI.

Sorry but I don't like Hydrogen for any use. It is expensive and dangerous. The numbers I read show it is 8 times less efficient than direct Solar PV or wind. Storing and compressing it takes a lot of energy. It can leak and explode very easily. The FOOL cell oh Fuel cells are expensive and fail if the H2 is not clean and pure. No thanks on H2.  

Oghosa Erhahon's picture
Oghosa Erhahon on Jan 21, 2022

Hi Jim, 
I completely understand your sentiments towards hydrogen. I do not 100% agree for H2, even from renewables to be used for domestic storage or yet alone electricity generation. 
However, Hydrogen has been been used for years, it's not new (check Air, Linde etc). The emphasis is towards low carbon processes - especially for hard to abate sectors e.g. steel industries for hydrogen, preferable green hydrogen from renewables to be used. 

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