Technology Opinion: Solar Hydrogen
25 May 2017

Investment in battery technology can be expensive, particularly if there is a sizeable demand. James Bolton, head of the Total Construction Renewables team, has been looking into some emerging energy storage alternatives with the ability to despatch larger quantities of energy. Below are some of his findings.

In a perfect world.
Ideally, we would be able to convert stored energy into electricity on demand. The storage duration would have little or no degradation and be repeatable without needing to replace the storage medium. If the energy storage could be used for heating, that would be a benefit. The absolute best outcome would be a low (or no) footprint.

What’s out there now?
A US company, called H/Cell Energy Corporation, is making huge strides in the area of solar hydrogen creation and storage. For example, the company’s HC-1 system can extract hydrogen from water using electricity sourced from solar PV. Unlike batteries, hydrogen energy can be stored indefinitely.

How does the HC-1 work?
The HC-1 is made up of solar panels, inverters, batteries, a hydrogen generator, a fuel cell and a hydrogen storage tank. The system uses electrolysis to create electricity by separating water – potable, mains or collected rainwater – into hydrogen and oxygen. The hydrogen is then stored in an inground tank that is scaled to suit the storage needs, and later fed into a fuel cell where it recombines the hydrogen with air to create electricity. The electricity goes to a small bank of batteries to be used on-site or dispatched to the grid.

Water input is minimal.
When the gases recombine, the output is also water. That means the water can be recovered and re-used, making the process highly repeatable with very little water top-up required. As a guide, when comparing against the cost of 'pure' battery storage system with greater than 3-4 days of storage, the hydrogen storage system is more effective. For an aged care facility with a 150kW or 200kW solar PV system and demand of 400 kW or higher, a hydrogen storage system should be more attractive than an equivalent amount of battery storage, particularly if battery replacement costs are factored in.

No CO2 or other greenhouse gases.
As a fuel, hydrogen produces no carbon dioxide or other greenhouse gases. The only emissions from hydrogen are chemically pure water and oxygen.

Blended fuels and heating.
In Australia, James points to the availability of another relatively new product called Hythane™. A mixture of 20% hydrogen and Compressed Natural Gas (primarily methane), it produces significantly less emissions than diesel or natural gas alone.
Boiler vendors, too, are beginning to acknowledge the benefits of hydrogen-blend fuels. In the UK, there is also a pure hydrogen boiler.

In conclusion.
If minimum emissions are the goal, a combined heating and electricity hydrogen-based system is about as pure as you can get. If the aim is to maximise the electricity generated and used from your solar panels, then hydrogen storage is an interesting candidate.

What do you think? Let us know in the comments!