What is hydrogen, and how can it be used to power our homes?
Hydrogen – an alternative to Natural Gas.
Hydrogen can be used as a backup for renewable energy sources such as solar and wind power. Unlike current renewables, hydrogen is not reliant on certain weather conditions.
It can be used alongside current renewable energy and stored up for when the supply doesn’t meet the demand.
(image: Power Engineering International.)
So what can we use hydrogen for?
A replacement for fossil fuels.
Stored as a feedstock for industry and chemicals.
A way of supporting renewable power and heat.
Using hydrogen safely.
Like natural gas, hydrogen is flammable and ignites easily. It’s vital to understand it’s properties to be able to use it safely in the same way we have with natural gas, such as adding an odorant to easily spot leaks.
Hydrogen is non-toxic and has no colour, taste or smell, so it’s very difficult to detect.
The gas is less dense than air, so will float away, but could build up indoors and cause a fire or explosion.
Where does hydrogen come from?
Hydrogen is a common element, however there are no large reserves of it on earth. It bonds with other elements, for example oxygen (water), we need a process to separate it.
Currently, 95% of hydrogen production comes from coal or natural gas, which produces greenhouse gas emissions. We need a low-carbon method of production. There is vast research going on to create more green and cost effective methods.
Steam methane reformation (SMR) is the most common production method at the moment. This process combines methane and water at approximately 900°C which produces a mix of carbon monoxide, carbon dioxide and hydrogen.
Gasification is a process where it is made from coal. Above 750°C the carbon in coal reacts with the water to form a mix of gases including hydrogen and carbon dioxide.
Using fossil fuels to make hydrogen produces waste greenhouse gasses which must be prevented from reaching the atmosphere.
Electrolysis is the process which uses electricity to split water into hydrogen and oxygen. Any hydrogen produced is low carbon as long as the electricity used is from low carbon sources. Currently only less than 5% of hydrogen production comes from this process. This method works at a much lower (20-100°C) temperature.
There are current plans to create an offshore platform in the North Sea, powered by wind, bringing the hydrogen onshore using existing pipelines.
(image: the Department of Energy.)
Biomass is another energy carrier that can be used. It can be mixed with steam and oxygen to produce hydrogen without combustion.
So how Green is hydrogen power?
Blue Hydrogen. Carbon capture technology is not yet widespread. It’s likely that hydrogen made from natural gas will become more common as the technology becomes more widely used and affordable.
Green Hydrogen made from renewables could potentially become the dominant source of hydrogen as renewable energy sources improve and the equipment required falls in cost.
How can we transport Hydrogen?
Hydrogen could be pumped through existing gas pipelines that are in use, also transported in compressed containers on trucks and trains.
Cooling hydrogen to a liquid form would compress a lot more energy in to the same space, currently this is expensive and energy intensive though.
(Image: the Yale School of the Environment.
Hydrogen in the home.
Heating and cooking appliances would need to be adapted or replaced to be used with hydrogen, but upgrades could be relatively straightforward and quick.
Producing energy for heating and cooking in the home without fossil fuels is an enormous challenge. A mix which is 20% hydrogen and 80% natural gas could be used in the existing gas network without changing any appliances or pipework. This would enable a small (apx 6%) CO2 saving compared with using 100% natural gas.
Hydrogen can escape through smaller holes in the event of an old damaged pipe or joint, and burns at a higher temperature than natural gas, so certain modifications are essential for appliances to work effectively and safely. Companies are already working on these adaptations.
It’s going to be a very interesting few years seeing how these developments come along.
Within our lifetimes we could look back at our current energy sources in the way we look at the historical burning of coal and smog filled cities of the industrial revolution.
There is so much information about these changes, and still a lot of work to do, much more information can be found on the Energy Institute Knowledge Service (EIKS) website.