Hydrogen for Home Heating is a Scam.

Friends, you may have heard that using hydrogen for home heating is somehow a ‘green solution’ to the question of how we should heat our homes in the future. This is not the case, but fossil fuel companies are still promoting the idea (1 , 2):

• Firstly they suggest that hydrogen heating for a home just replaces a familiar boiler with an outwardly similar device at lower upfront cost than a heat pump.
• Secondly, they additionally spread fear, uncertainty, and doubt (FUD) about heat pumps.

Hy Street!

Companies are preparing hydrogen-burning boilers for domestic applications

Remember each year they delay the transition to heating our homes with renewable energy is another year of profits for their shareholders, and ongoing pollution of our atmosphere. And a world in which we use hydrogen for home heating is a world in which demand for methane (so-called ‘natural’ gas) will increase – not decrease as it must if we are ever to reach net zero.

This article is an explanation of why hydrogen is not any kind of a solution for home heating. It’s complex, but I’ll do my best to be as clear as possible.

But I urge you to keep in mind the key characteristics that any solution to the problem of home-heating must have in order to qualify as a solution:

• It must have drastically reduced carbon dioxide emissions – with an ideal limit of zero emissions.
• And it must have a way to begin that reduction right now: we really have no time left.

If a proffered solution does not meet these goals, it is not a solution at all: it’s a scam.

Shades of Hydrogen

When one combines hydrogen (H2) with the oxygen (O2) in the air to release heat, no carbon dioxide is produced. The exhaust gas is pure water, H2O. So at the point of combustion, all hydrogen is nominally free of harmful emissions.

But to understand its environmental impact one must take account of the amount of carbon dioxide emitted in the preparation of the hydrogen gas, and its transport to the point of combustion. The pre-history of the hydrogen gas is commonly summarised by a colour pre-fix. However, is not actually coloured and it behaves identically no matter how it is prepared.

• Green Hydrogen: Hydrogen which is prepared from water using renewable electricity is referred to as Green Hydrogen. Ideally, it has no associated carbon dioxide or methane emissions.
• Grey Hydrogen: Hydrogen which is prepared by combining water with methane at high temperatures (so-called Steam Reforming) is referred to as Grey Hydrogen. This process produces carbon dioxide which is emitted into the atmosphere.
• Blue Hydrogen: Hydrogen which is prepared by Steam Reforming but in which the emissions are captured is referred to as Blue Hydrogen. This process still produces carbon dioxide emissions because the capture process is never 100% efficient, and it is generally powered by burning methane.

A recent analysis (link) has estimated the  carbon dioxide emissions associated with the production of Grey and Blue Hydrogen. Its estimates of the carbon dioxide equivalent emissions associated with an amount of hydrogen gas which releases 1 kWh of heat are shown in the chart below:

Click on image for a larger version. Chart showing the carbon dioxide equivalent emissions from burning pure methane, green, blue and grey hydrogen. For blue and grey hydrogen, the emissions are shown with and without the effect of methane leaks. A methane leakage rate of 3.5% is assumed.

As discussed below, in this abbreviation the ‘eq’ stands for equivalent. This can be compared with the carbon dioxide emissions associated with simply burning the methane gas directly.

There are two contributory factors to this result. The first factor is the inefficiency of carbon capture and the fact that extra energy is required to process either grey or blue hydrogen.

The second factor is an assessment of rate of methane leaks – so-called ‘fugitive’ methane emissions. The author’s central estimate is that in the global supply chain, around 3.5% leaks directly into the atmosphere. Evaluated over 20 years, this fugitive methane has a heating effect of around 84 times as much as the same amount of carbon dioxide. The warming effect of the fugitive emissions is expressed in terms of the equivalent amount of carbon dioxide emissions which would produce the same warming.

So according to this study, if we convert methane to hydrogen assuming reasonable (3.5%) estimates of methane leakage, there are no reductions in emissions at all. In fact, there is an increase in emissions! If we unrealistically/optimistically assume no methane leakage, then grey hydrogen still has increased emissions, and blue hydrogen offers a maximum reduction in emissions of just 20%.  There is no path to zero emissions using either grey or blue hydrogen.

So the outcome of this research is that using methane  to prepare Blue or Grey Hydrogen may slightly reduce emissions, but even in the best circumstances, not by much. Only Green hydrogen offers the possibility of a fuel which would reduce emissions to zero.

Pure Green Hydrogen

It is not possible to send green hydrogen – or any other colour of hydrogen to our homes at the minute. Firstly, the gas distribution network is currently being used for methane! Secondly, there is not enough hydrogen to supply to the UK. And thirdly, compared to methane, hydrogen has a very low energy density i.e. energy per cubic metre. So to deliver the same heating power into our homes as methane currently does, we would need to operate the gas delivery system at roughly 3 times its current pressure.

Operating a hydrogen gas distribution system at high pressure is a bad idea for all kinds of reasons, but I don’t want to dwell on those reasons right now. All I want to point out is that even with the most ‘advantageous’ assumptions, we are decades away from switching to a pure hydrogen gas distribution system. In those decades, fossil fuel companies propose that we basically just keep burning methane – and delivering them their profits.

But referring back to the start of this article, if we can’t start now, then what is being proposed is not a solution. It’s a scam designed to keep us using methane gas for decades more.

A foot in the door: Hydrogen-Methane Mixtures

So the fossil-fuel industry’s plan to place themselves at the heart of future home-heating is the proposal to mix hydrogen with methane and distribute this through the existing gas infrastructure. Existing boilers can tolerate up to about 20% of hydrogen mixed into the methane, and their power output will only fall by about 7%.

The effect on carbon dioxide emissions per kWh of heating delivered is shown in the two figures below. The first graph is based on an assumption of 3.5% leakage of methane and the second assumes an unrealistic 0% leakage rate.

Click on image for a larger version. Graph showing the CO2-equivalent emissions as the fraction of hydrogen mixed into methane gas is varied from 0% to 20%. A methane leakage rate of 3.5% is assumed.

Click on image for a larger version. Graph showing the CO2-equivalent emissions as the fraction of hydrogen mixed into methane gas is varied from 0% to 20%. A methane leakage rate of 0% is assumed.

Assuming a 3.5% leakage rate, adding either Grey or Blue hydrogen to methane increases the so-called carbon intensity of the fuel mixture i.e. adding hydrogen increases the amount of carbon dioxide equivalent emissions per kWh of heating delivered.

Assuming a 0% leakage rate, adding Grey hydrogen to methane increases the carbon intensity of the fuel mixture but blue hydrogen could slightly reduce the carbon intensity, but only by around 1%.

So when it comes to mixtures of hydrogen in methane, adding blue or grey hydrogen generally results in an increase in the amount of carbon dioxide emissions rather than a reduction. So using blue or grey hydrogen does not represent a solution to the problem of carbon dioxide emissions. And of course, neither blue nor grey hydrogen are renewable – they still depend on endless mining of natural gas – and that is why they are being promoted: they allow fossil fuel companies to continue to carry on as before.

But what about green hydrogen?

Green Hydrogen

Looking at the graphs above one might think that green hydrogen looks like a possible solution to the home-heating problem: it does result in reduced carbon intensity of a green hydrogen/methane mixture. And in a hypothetical future world with a hydrogen grid, it might deliver heating with nominally zero associated emissions.

However, home-heating with green hydrogen is still a bad idea. To understand why one needs consider the renewable energy used to create the green hydrogen.

To create 1 kg of green hydrogen from water using electrolysis requires a minimum of 39.4 kWh of renewable electricity. When that hydrogen is later burned in air, all of that energy will be returned as heat.

But electrolysis is typically only 75% efficient, so more typically it requires 39.4/0.75 ~ 52 kWh of renewable electricity  to create 1 kg of  green hydrogen which will provide 39.4 kWh of heating. And since boilers are typically not 100% efficient, the amount of heat delivered into the home would be reduced further – to (say) 85% of 39.4 kWh – i.e. 33.5 kWh.

Is there something better that we could do with that renewable electricity?

With regard to home heating, Yes. If that 52 kWh of renewable electricity was used to power heat pumps, it would deliver approximately 156 kWh of heat to homes, more than 5 times as much heat as could be delivered by 1 kg of hydrogen.

Click on image for a larger version. Chart showing the amount of home-heating available from 1 kWh of renewable electricity.

This means that to create the same amount of renewable heat, heating homes with hydrogen would require five times as much renewable resource: five times as many wind and solar farms!

Now a hydrogen boiler is cheaper than a heat pump. In ‘ball park’ figures, let’s say that a hydrogen boiler might cost £3,000 to install and a heat pump might cost £10,000. These costs would be paid by the homeowner or landlord. This makes a hydrogen boiler look cheap at first sight.

But the cost to build five times the amount of renewable resource is very large

If we consider the cheapest renewable resource, onshore wind, a 10 MW turbine- big enough to generate on average around 3.5 MW of renewable electricity – this will likely cost around £10M. Nominally this single turbine would supply roughly 3,500 homes with 1 kW of electricity continuously, so one might guesstimate the cost as around £2,800 per household for 1 kW of continuous power.

So if we consider the total system costs, we have:

• For a hydrogen boiler, the ‘local’ cost is £3,000 + 5 × £2,800 to build the required renewable electricity resource to create the hydrogen. So the total cost is ~£17,000.
• For a heat pump, the ‘local’ cost is £10,000 + 1 × £2,800 to build the required renewable electricity resource. So the total cost is ~£12,800.

Now this is very much a ‘back of the envelope’ calculation – and there are many things I have not included, such as cost of building either a hydrogen capable gas grid, or improvements to the electricity grid. And I don’t put any store in the particular numbers in this calculation. But the calculation demonstrates that a green hydrogen ‘solution’ has very large costs that are not immediately apparent. And in the end, all those costs will be paid for by the consumers of the gas: us.

And friends, the UK is nowhere near having sufficient renewable capacity to generate these vast amounts of renewable green hydrogen. So the plan that the fossil fuel companies will try to sell is that they will start with blue hydrogen – and promise to slowly add green hydrogen to the mix. But of course, this will barely reduce emissions at all. But at its heart, the entire hydrogen for home-heating proposal is a scam to allow them to keep producing their toxic products.

In contrast, every home converted to using a heat pump immediately saves tonnes of CO2 emissions per year. So lowering the upfront cost of installing a heat pump through low-cost loans and grants is actually a national saving: it avoids the phenomenal costs of building the vast renewable resources required to produce green hydrogen.

So is Green Hydrogen pointless?

No! Green hydrogen is really important. If we want to live renewable lives then green hydrogen will be essential for some processes. But home-heating is just not one of those processes.

Michael Leibrich has produced a ‘Clean Hydrogen Ladder’ showing processes for which use of green hydrogen will be unavoidable, and processes for which green hydrogen will be uncompetitive.

Click on image for a larger version. The ‘Clean Hydrogen Ladder’. The use of green hydrogen is unavoidable in order to make fertiliser or feed stock for the chemical industry. But it is uncompetitive for applications such as domestic heating.

And we definitely need loads of green hydrogen to serve as feedstock for the chemical industry and for the manufacture of products like steel and fertiliser.

Summary

The solution to our home-heating problem is heat pumps: air source, ground source, air-to-air or air-to-water.

The idea of using hydrogen for home-heating is wasteful. It is a ruse of fossil fuel companies to allow them to keep producing their toxic products. Please don’t fall for this scam.

Tags: Hydrogen