Hydrogen has been getting a lot of attention already, and we’re being asked by a number of installers what we think about hydrogen, in particular it’s place in the future of UK heating.
UK Hydrogen Strategy
The Government has recently published it’s UK Hydrogen Strategy, where it outlines its view on the role hydrogen will play in the low carbon economy over the coming decades.
With regards to heating in homes, the Government states that a range of low carbon options are going to be needed, and that hydrogen could be one of them:
Low carbon hydrogen could be one of a few key options for decarbonising heat in buildings, alongside more established technologies such as electricity and heat networks. While there is more work to do to test the feasibility of using hydrogen, it could become a like-for-like alternative for buildings currently heated by natural gas from the grid.
That said, the Government does also acknowledge that the overall contribution from hydrogen is likely to be limited in the next 10 years:
Although we expect overall the demand for low carbon hydrogen for heating by 2030 to be relatively low (<1TWh)
Our Response
Our response and views on the UK hydrogen strategy are outlined below:
Energy Mix
In broad terms, we are supportive of any future energy mix that reduces harmful greenhouse gases. Whilst clearly Alto Energy are passionate advocates of heat pump technology, we accept that there are a number of properties in the UK that are not likely to be suitable for a heat pump, and will therefore rely on a traditional “combustion” type system. We also accept that given the small size of the UK heat pump industry in the present day, to expect heat pumps alone to reach 24 million UK homes and decarbonise UK heating as a sole solution to the problem, is unrealistic.
Beware Blue Hydrogen
There has been a lot of talk in the press about the different “colours” of hydrogen. The graphic below illustrates the different types of hydrogen:
Grey Hydrogen -
This is how must hydrogen is currently made, Hydrogen is extracted from methane (CH4 - natural gas) in a chemical process that yields hydrogen and carbon dioxide. The result is far more carbon dioxide emissions than would be yielded from simply burning the natural gas in the first place. So this is not an option for any low carbon strategy.
Blue Hydrogen -
This is being talked about a lot. Blue hydrogen is made through the same process as Grey hydrogen, except for the fact that the carbon dioxide is captured at point of production, and buried underground. In theory this means that there is no carbon dioxide, however this process is fraught with issues.
Green Hydrogen -
This is the future aim. Green hydrogen is made through electrolysis - which is the splitting of water (H2O) into hydrogen and oxygen. The process is driven by surplus, zero carbon electricity from wind turbines or solar panels, and used to produce hydrogen.
So what’s the problem with Blue hydrogen…?
The net benefit of blue hydrogen to the environmental challenge is heavily debated. In fact, after the release of the UK hydrogen strategy the chair of a leading hydrogen industry associated resigned, citing false claims made by oil firms regarding the benefit of blue hydrogen.
The main issues we see are two-fold:
Firstly, methane leakage. For starters, the process for converting methane to hydrogen is inefficient, so to start with you need more methane in the first place. Thereafter, extraction of hydrogen from methane is a much more complex chemical process than simply burning the methane. This means that the methane must pass through reformers, pipelines, ships etc… all of which give rise to a greater opportunity for the methane to leak. Methane is a much more potent greenhouse gas than carbon dioxide itself. A recent study by US researchers indicated that the result of this is that creating blue hydrogen from methane was 20% worse for the environment than simply burning natural gas.
Secondly, carbon capture and storage. Carbon capture and storage remains a process that has yet to be successfully deployed on a commercial scale. And moreover, the notion of capturing carbon and burying it underground feels like something that could create consequences down the road for future generations.
Efficiency per unit of electricity
Ok, so green hydrogen. This is something we can definitely get on board with. In a future UK electricity grid powered by nuclear, wind and solar, there are bound to be periods of excess. During these times, the excess can be used to make zero-carbon hydrogen - green hydrogen. This can be used for a whole host of applications, including heating. However, from an efficiency perspective compared with a heat pump, hydrogen heating feels like a very inefficient way to use that surplus electricity.
To go from a unit of electricity from a zero carbon source, to a unit of heat from a hydrogen boiler, the following needs to happen:
Electricity to electrolysis, to split water into hydrogen. Typically ~ 75% efficient.
Hydrogen to heat through a hydrogen boiler. Typically ~ 75% efficient.
Total heat from 1 unit of electricity = 0.56 units
For a heat pump, the unit of electricity is used to extract heat from either the ground or the air, and so the following happens:
Electricity to power a heat pump. Typically ~ 350% efficient
Total heat from 1 unit of electricity = 3.5 units
So as you can see, for every unit of zero carbon electricity, a heat pump will deliver between 6 - 7 times as much heat, compared to a hydrogen boiler. So whilst we 100% advocate the develop of the green hydrogen economy, when it comes to heating to do feel that hydrogen should be reserved for the hard-to-heat properties, where a heat pump is not suitable.
“For every unit of zero carbon electricity, a heat pump will deliver between 6 - 7 times as much heat, compared to a hydrogen boiler.”
Nitrous Oxides
What we are talking about with hydrogen boilers is combustion, just like with natural gas. The simple chemical equation for the combustion of hydrogen is very simple:
Hydrogen + Oxygen = Water + Energy
Great, no carbon dioxide! However, be warned. The equation about is based on combustion with pure oxygen. However, in household boilers, we’re talking about combustion in the presence of atmospheric air, which is 78% nitrogen.
As a result of the heat generated by the flame in the boiler, impurities are also formed which happen as a consequence of the desired reaction. The most abundant impurity in combustion boilers is nitrogen dioxide. Nitrogen dioxide, whilst not a greenhouse gas, has a serious impact on air quality. Back in industrial times coal burning gave rise to huge smog clouds over industrial cities, and had a serious impact on human health.
Now, whilst hydrogen might not be that bad, recent studies indicate that it could be up to 6 times worse than burning natural gas. So this is definitely an area that needs to be monitored closely.
Conclusion
We think hydrogen is a key aspect of a low carbon economy in the future. However we believe that the use of blue hydrogen - which the Government accepts would be a significant component of the growth of the hydrogen economy in the next 10 - 20 years - is a false economy. Green hydrogen is a very exciting prospect, promising a zero carbon fuel source which can be created, relatively efficiently, from surplus electricity. However, using this hydrogen to heat homes feels like a much less efficient use of that electricity, compared with storing it in a battery and then using a heat pump to generate heat. As such. the best use of hydrogen in the heat sector is for those hard-to-heat applications, where a heat pump would not be suitable.