Are Hydrogen Energy Storage Systems Ready for Residential Use

Pacific Energy Advisors along with our MEP engineering design partner Monterey Energy Group, were recently asked to investigate the state of Hydrogen Energy Storage Systems (HESS) for the residential and light commercial markets. In our global search for where the technology stands, we found a few pioneering companies with emerging technologies that have the potential to impact these markets, but one stood out like a lighthouse in the Monterey Bay fog.

Hydrogen energy storage is a form of chemical energy storage that involves electrical power conversion into hydrogen, followed by storage, then conversion back into electricity when needed. Its application is very similar to battery energy storage systems (BESS), as they both work to offset peak electrical demand by storing and supplying available energy when necessary.

Just like battery energy storage systems (BESS), pairing hydrogen energy storage with solar or wind turbines can reduce peak energy demand and provide energy for prolonged public utility power outages or weather events.

As wind turbines and solar PV panels become cheaper, so does the cost of producing green hydrogen from renewables through electrolysis. Hydrogen offers the potential for longer duration energy storage — it complements battery solutions to provide flexibility to the grid, delivering energy on a much larger scale.

In terms of energy storage density, hydrogen generally outperform lithium-ion batteries. This gives it a significant advantage when it comes to storage capacity. In our view, we see these two technologies (BESS and HESS) working together to deliver energy where and when it’s required.

The Four Hydrogen Challenges

Storage

Storing hydrogen can be done as a gas, liquid or in a solid-state form. Gaseous hydrogen requires storage under very high-pressure to be feasible, with some large commercial applications using enormous salt domes 3,000’ feet underground. Liquid hydrogen requires storage at cryogenic temperatures, around -252 centigrade. These two storage types are not practical for residential applications.

As hydrogen can be stored within a solid by absorption, this method holds some promise on a residential scale. We recently had the opportunity to visit GKN Hydrogen in their new Carlsbad, CA. office, where we spent an afternoon looking at one of their production hydrogen energy storage systems.

Having worked at Royal Philips Electronics in a previous career path, I came to fully appreciate what it means to be a vertically integrated manufacturer, and that’s just what GKN Hydrogen is. This internal spin off from GKN Powder Metallurgy is pioneering safe and emission free storage of green hydrogen.

Not ironically, GKN Powder Metallurgy developed a low temperature, solid-state metal hydride, which enables a significantly smaller hydrogen storage footprint and increased safety. GKN Hydrogen took that hydrogen storage technology, optimized it, and developed their hydrogen energy storage system (HESS) around it, which they call their HY2 product line.

Electrolyzer (Hydrogen Production)

GKN Hydrogen uses a compact electrolyzer suitable for residential applications which produces high quality hydrogen gas. The electrolyzer can be scaled up to 4 units to match the storage and output requirements of the system, typically configured with a single 8 kW output fuel cell.

Hydrogen from the electrolyzer is then fed into the storage cells containing proprietary metal compounds able to dissociate hydrogen molecules and form a metal hydride with atomic hydrogen in the solid-state. This method of energy storage does not degrade (batteries suffer from self-discharge and reduced capacity over time) and has an extremely long expected life of 30+ years.

When required, atomic hydrogen is released from the storage cells and recombines to form molecular hydrogen (H2) which is then fed into the fuel cell to produce electricity.

Fuel Cell Output Limitation

So, you have a hydrogen storage system which can store lots of energy for long periods of time but is limited in raw energy output and only about 50% efficient at this stage. It became obvious that you won’t be running anyone’s home on 8kW of electrical output.

For this reason, we wouldn’t recommend a standalone Hydrogen Energy Storage System, at this point, to meet a property’s energy needs. It’s best integrated into a mix of renewable and/or a grid tied system to provide long duration energy capacity to help maintain and top off a battery energy storage system (BESS) during power outages and severe weather events.

Efficiency

Getting to higher round trip energy efficiency is where GKN Hydrogen introduces a Combined Heat and Power unit (CHP) into their system. CHP essentially captures waste heat, in this case the heat output from the Fuel Cell and converts that into thermal energy which can be used to heat domestic hot water (DHW) and other thermal energy demands.

When combining all the elements that GKN Hydrogen has baked into their HY2 HESS, the round-trip efficiency approaches 70%, which now becomes economically attractive, even for the residential market.

GKN Site Visit

We visited with Alan Lang and Clark Crawford of GKN Hydrogen in Carlsbad, CA. to get a firsthand look at the smallest of their systems, the HY2MINI. The system is delivered to the site in a 10’ shipping container where it is connected to the I/O of the property’s energy system.

This is a fully contained HESS and it was very cool for our CTO, Craig Bercaw and Abe Stallcup from Monterey Energy Group to Q&A with the GKN Hydrogen team.

Looking into the production end of the system you can see the hydrogen storage system on the left and the electrolyzers and fuel cell system on the right. The orange PEX tubing is part of the CHP that takes waste heat and converts it to thermal heat.

GKN Hydrogen’s System Specialist Ivo is showing us the high voltage side of the container, which is partitioned and isolated from the hydrogen production side, as a standard safety protocol, because gas and electricity don’t mix well. In fact, the whole system comes with several safety features to make owners feel very comfortable with this new technology.

The system also comes with some battery storage to meet initial demand loads while the fuel cell starts up. The control interface is above and behind those batteries.

The solar inverters are located within the cabinet’s starboard side to connect to the solar input for the system. The port side contains the heat pump and dry cooler, which support the CHP and provides environmental control for the entire system.

One obvious question property owner’s might be is where do I hide the box? GKN Hydrogen has designed the ability to hang panels from the sides enabling branded or decorative graphics to help blend in with the background or theme. You’ll see examples in our next section on Use Cases.

GKN Hydrogen Use Cases

GKN Hydrogen has around 20 installations around the world. We are highlighting residential, light commercial and off-grid applications here. Got a mountain estate or resort you want to be totally green?

Knappenhaus, South Tyrol, Italy

At 1,600m (about 5249 ft) above sea level, Knappenhaus sees about 1.5m of snow and temperatures as low as -25C. This 400-year-old home has never been connected to the public grid and this HY2 pilot system has been supplying the house with electricity and heat since 2018.

Sustainable hospitality is the theme of the Arieshof in St. Lorenzen, South Tyrol, Italy. Combining sustainability, organic farming, and innovative energy to showcase that future proof and energy self-sufficient infrastructures are possible today.

Arieshof, St. Lorenzen, South Tyro, Italy

The Aireshof has over 1,000 square meters of solar that supply electricity for daily operations. What is not needed immediately, is stored in their innovative hydrogen storage system to cover peak energy demand and system or weather-related outages.

What about California?

Ah yes, lest we forget about the most regulatory challenging state to get anything done in, GKN Hydrogen has installed their HY2 system at a remote commercial Micro-Grid in the Mohave desert. This matters to us, because it means that GKN Hydrogen has already been through the regulatory hoops to get their system permitted, approved, and commissioned in California. This includes all the certifications from UL, to ASME and all the others required from a manufacturer to get permitted in the state. Trust us, not all manufacturers are compliant in this regard.

Because most of our projects are in California, we are uniquely aware of the regulatory challenges for permitting energy systems. Many locales no longer permit gas hookups or even backup generators and limit the amount of on-site battery storage. Throw in the move from NEM 2.0 to NEM 3.0 and when you’re building a 7,000 square foot home, these things matter – quite a bit. Hydrogen may be part of the solution going forward when other energy sources are limited.

Economics and Summary

Today, these systems are ideally suited for large and light commercial applications to complement renewable and battery storage systems, working in concert to deliver energy where and when you need it. GKN Hydrogen estimates they will be able to realize greater efficiencies within 2 years as they scale up production. Meaning it will become more affordable for the early adopters as time goes by.

Most projects we work on are in that 18-24 month build horizon and it behooves you to engage with your energy consultants early in the project to help architect the energy infrastructure that gets turned on 2 years later. Should hydrogen be part of your energy architecture? We can help answer that question by modelling it as part of your long-term build and energy infrastructure.

About Pacific Energy Advisors

Planning, building, and executing your custom homes energy system is not a trivial matter and costs can run between 5% and 8% of a new home’s budget.

With so many competing technologies and systems in the market, how do you net it out to get what you really need? We are firm believers in “Do it once and do it right” and most prepackaged systems often leave you short on power when you need it most and they do not take your lifestyle into consideration.

Pacific Energy Advisors takes the guesswork out of the equation by architecting the right system that provides energy you can use, where and when you need it, and we help you do it as economically as practical.

About Monterey Energy Group

MEG is one of the only licensed engineering firms offering Mechanical, Plumbing and Energy engineering in house who is also an expert in T24 Compliance. These 4 scopes are critical in all building projects, and bundling these services will save time and money in both design and construction phases by coordinating systems that work well together across each of these trades.

For more information contact:

Todd Wulfert todd@pacificenergyadvisors.com 415-608-1434