Review of the Heat and Buildings Strategy

Last month the government announced the long awaited Heat and Buildings Strategy [1] which sets out plans to convert this sector to net zero GHG emissions. This came out almost at the same time as the wider Net Zero strategy [2]. One aspect I was particularly interested to see was the plan for hydrogen in heating – there is still indecision in this area we will have to wait until 2026 for more certainty. Another aspect is the balance between electricity and gas energy costs, also support for retrofitting heat pumps into homes and building up the supply chain for retrofit. There are definitely some good things in this policy but some serious gaps.

Scenarios: high hydrogen, high electric or in-between? 

The future role of hydrogen is still uncertain and the Net Zero Strategy refers to three scenarios for heating in the future. In all cases, heat pumps have a very large role. As well as the net zero in 2050 target there is an interim target to reduce GHG emissions from this sector by about two thirds by 2035.

By 2035, the target is for 13 million homes to be on low carbon heating of which two million will be on heat networks. For the rest there are different scenarios. If hydrogen does not work out, almost all the rest will be on heat pumps. If hydrogen does work out, then we can expect up to 4 million on hydrogen gas by 2035 and 7 million on heat pumps. Or, it could be something in-between.

Whatever happens, at least a third of homes in the UK need to be heated by heat pumps by 2035 – a lot more than on hydrogen.

Comparing blue hydrogen with natural gas emissions

Hydrogen is in the news a lot lately, because of the publication of the UK government hydrogen strategy document. I was alarmed to find a recent article [1] saying that blue hydrogen (made from methane gas with carbon capture) is hardly better than grey hydrogen (made from methane without the carbon capture). The authors are Robert Howarth from Cornell University and Mark Jacobson from Stanford University). I have recently been saying that blue hydrogen is at best about a third the emissions from methane gas, which I think is bad enough - but this article suggests even that is naively optimistic. 

Obviously there are some vested interests trying to paint blue hydrogen as white as possible (pun intended). So I decided to dig deeper into the assumptions behind the analysis. There are three main sets of assumptions involved - about the upstream emissions, about the capture rates and about the source of energy used in the hydrogen conversion plant. Plus you can choose to use 100 year global warming potentials for methane or 20 year ones. Given the climate emergency, the 20 year timeframe seems more appropriate. Also I have chosen to compare blue hydrogen with natural gas, which is the fuel it would mostly replace. Depending on the assumptions you choose, you can make blue hydrogen decidedly worse or significantly better. I can only get it down to 1/3 the emissions of natural gas using the 100 year time frame, not over 20 years. 

Emissions from natural gas and blue hydrogen with the original assumptions in [1]. NG is natural gas, Blue is blue hydrogen, 100 years/20 years means using the 100/20 year global warming potential for methane 

Climate change stories to be cheerful about

It has been a very difficult year for several reasons. But it was not all bad. To cheer us up over the holiday, here are my favourite good news stories from 2020 - including coal consumption down, renewables up, beavers for flood management, hope for the survival of coral, help in eating more plant proteins, and changes to our travel behaviour.

Is the gas industry promoting uncertainty as a delaying tactic?

We have to decarbonise our heating systems, but there are competing options as to how this is best done: electric heat or green gas. Whatever happens this is going to be very disruptive for industry sectors including oil and gas supply and appliance manufacturers - some very large corporations face an existential threat. So it is hardly surprising that the gas industry is lobbying our government intensively, arguing that green gas is a practical, inexpensive alternative to electric heat. It is not clear that they have successfully driven policy decisions in their favour, but it is possible that they have achieved delays to measures that are needed urgently. Or are ministers simply putting off decisions that they believe will be unpopular? As one consultant said (of decarbonising heat policy): Anything that puts people’s bills up is a big issue. And anything involving intervening in people’s homes is a big issue. You’ve got them all. It’d be an absolute car crash. [1]

This blog post is inspired by two journal papers by UK academics Richard Lowes and Bridget Woodman from the University of Exeter, and Jamie Speirs from ICL. You can find them here:

[1] Disruptive and uncertain: Policy makers’ perceptions on UK heat decarbonisation (Energy Policy) 2020

[2] Heating in Great Britain: An incumbent discourse coalition resists an electrifying future (Environmental Innovation and Societal Transitions) 2020

As academic papers go, these are very readable. I particularly like the extensive quotes in the first one, one of which you have read in my first paragraph. Both are based around interviews with people who have influence over policy - from Ministers and civil servants to industry reps, 3rd party consultant and NGOs.

Converting the gas grid to hydrogen, starting with Leeds.

Low carbon electricity is within our sights but low carbon heating is more difficult. Most UK homes use natural gas (methane) and switching to renewables (electricity or biomass) is expensive, even when it is practical. Northern Grid Networks (NGN) have another suggestion - converting the gas grid to supply hydrogen.  This is carbon free at the point of use but not usually where it is made - the NGN proposal is to convert from methane and sequester the carbon stripped off. This will give, at their estimate, 59% reduction in emissions. However once have we have a hydrogen distribution network other options, including carbon negative ones are possible. The big questions is, is it practical to convert the grid to hydrogen? NGN propose that we use Leeds as a pilot city and they have produced a detailed plan: H21 Leeds City Gate. They have convinced me that it is technically possible, and the biggest barrier is cost, but even this is not ridiculous compared to other means for carbon savings. The diagram below shows the concept.

Overall concept for H21 - including gas supply to the steam reformers, salt caverns for storage and hydrogen pipelines. In the city hydrogen would flow through the existing gas distribution network. Image 1.6 from [1].

Dealing with excess wind

Wind as a source of energy is clean but not reliable; too much is not quite as bad as too little but it is still a problem. It seems a shame to have to stall the blades and stop generating on windy days, even though wind is free. There are three reasons why you might need to do this: because there is more wind power available than electricity demand, because taking the wind power would mean shutting down something else - like nuclear - which isn't flexible enough to turn on and off, or because there is more wind available than there is grid capacity to take the power (see Why do we pay wind farms to switch off). Apart from the last case we haven't hit these problems yet but other countries like Denmark and Germany have. If only we could store the excess energy to use later - but maybe we can. Lots of engineers have been working on this problem, especially in Germany, and there are pilot plants running for some of the technologies. The ones which store power as gas are particularly interesting because we can store gas over long periods - from summer to winter if necessary.