Category Archives: residential

Hydrogen and heat pumps may both play a role in UK building heating

Low carbon hydrogen and electricity via heat pumps may both play a large role in decarbonising building heating in the UK.  Ways forward are needed that maintain optionality around solutions while more is learnt about the right mix.

This is the second of three posts looking at the potential role of hydrogen in residential heating in the UK.

Decarbonising building heating in the UK poses a range of challenges.  First, the required transition is very large scale.  There are around 27 million households in the UK, with many more commercial buildings, small and large.  This implies around a million or more premises a year on average need to be converted to low carbon heat between now and 2050.

Along with scale, there is cost.  Replacing the UK’s heating system is expensive both on in total and by household, even if the existing natural gas network can be used for hydrogen.   This challenge is made more difficult by the high seasonality of heating demand (Chart 1).  Building natural gas supply chains, reformers to produce hydrogen from natural gas, CCS, low carbon electricity and heat pumps all involve major capital investment.  Running this for only part of the year – the colder months – increases unit costs substantially. The chart below shows daily gas and electricity demand from non-daily metered (i.e. small) customers.  Demand for energy from gas, the major source of building heating at present, is about two or three times electricity demand during winter, and is much more seasonal.

Chart 1: Heating demand is highly seasonal …

Source: BEIS (2018) ‘Clean Growth – Transforming Heating’ https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/766109/decarbonising-heating.pdf

Furthermore, the transition to low carbon heat needs to be made largely with the UK’s existing building stock, which is mainly old and often badly insulated.  Improved insulation is a priority in any programme, but there are practical and cost constraints on what can be done with existing buildings.  (Buildings also need to be able to cope with the increased prevalence of heat waves as the climate warms, but that is a separate topic.)

Finally, building heating directly affects people’s day to day lives, so consumers’ acceptance is critical.  On the whole the present system, based mainly on natural gas boilers, works quite well except for its emissions.  Any new system should preferably work as well or better.

The leading candidates for low carbon heating in buildings are electricity, almost certainly using heat pumps to increase efficiency, and low carbon hydrogen.  Biomass seems unlikely to be available either at the scale or cost that would be needed for it to be a major contributor to low carbon heating, though it may find a niche.  District heating networks require low carbon heat and this must draw on the same ultimate set of sources of heat.  Waste heat from nuclear, once discussed as a possibility, no longer seems likely to be either practical or cost effective.

Recently the Committee on Climate Change (CCC) analysed the costs of decarbonising heat in 2050 using different approaches.  They looked at electricity, hydrogen, and combinations of the two.  The analysis concluded that a 50% increase over current costs was likely (Chart 2).  The remarkable thing about the analysis is that this cost was similar for all of the options considered.  Any differences were well within the uncertainty of the estimates.

Chart 2: Costs of different modes for decarbonising building heating …

Source:  Committee on Climate Change

With no large cost difference leading to one or the other option being preferred there is a need to test each option out to see which works better in practice.  Mixed solutions may be appropriate in many cases.  For example, hydrogen may be useful in providing top-up heat even if heat pumps are providing the baseload, or may be the only solution for some poorly insulated properties for which heat pumps don’t run at high enough temperatures.

The CCC’s analysis includes expected cost savings.  The transition to low carbon heat will clearly be more acceptable if this cost can be reduced further.  In particular there seem likely to be both technical advances and large economies of scale in heat pump manufacture and installation, and the costs of low carbon power may fall by more than assumed by the CCC.  As the analysis stands, a 50% increase is clearly politically difficult, especially when there do not seem to be advantages for the customer, and potentially some drawbacks.  However, this is less than a 2% p.a. compound increase in real terms over a 30 year period, which might be politically feasible if introduced gradually spread across all consumers.

With such large changes in demand between summer and winter, seasonal storage is a major issue for reasons of both cost and practicality.  This is an under-researched area, and needs further work.  There are various possibilities – storage of hydrogen itself in salt caverns, storage of hydrogen as ammonia or storage of heat in ground sinks, but each has its problems and the scale involved is very large.

A final uncertainty is the form which hydrogen production will take.  At the moment methane in reformers predominates and, with the addition of CCS, may continue to do so.  However both the costs of low carbon electricity and of the electrolysis are decreasing rapidly.  Over the long term this may become the main pathway for hydrogen production.

These uncertainties imply that building heating poses a particularly difficult set of choices for policy.  It is not clear what route, or mix of routes is the right one.  The transition needs to be quite rapid relative to the lifetimes and scale of existing infrastructure, and it involves the need for consumer acceptance.  There are also potentially strong network and lock in issues.

The best approach is likely to be to develop several types of solution in parallel, maintaining optionality while learning, and being prepared for some approaches to be dead ends.  The implications of this include the need for roll out of low carbon heat sources in some districts now to get an idea of how they will work at scale.

Some of this is happening, much more is needed.

Adam Whitmore -29th October 2019.

 

Comparison of cost estimates with previous analysis by this blog.

Around four and a half years ago I looked at the costs of decarbonising domestic heating in the UK in winter using low carbon electricity.  I concluded that switching to low carbon heat would add 75% or more to domestic heating bills, with some drawbacks for consumers (I also looked at higher cost case, but this case no longer seems likely due to the fall in the costs of low carbon electricity, especially offshore wind, since the analysis was done.)  I suggested that this meant that the transition would be difficult and that reductions in capital costs were necessary.

This analysis is broadly consistent with the CCC analysis quoted here, which suggests a 50% increase on current costs.  The estimates are roughly similar given the large uncertainties involved , the inevitable differences is assumptions, and different basis of the estimates.  In particular the CCC analysis factors in reductions in costs of low carbon heating likely by 2050, whereas my previous analysis was based on current costs to make the point that cost reductions are necessary,  Consequently it would be expected that the CCC analysis would show a smaller cost increase relative to current costs.  Also, the CCC’s analysis may exclude some costs – estimates such as these have a tendency to go up when you look at them more closely.  Equally it may understate the cost reductions possible over decades.

 

 

How well is the UK on track for zero emissions by 2050?

By 2020 the UK will have very nearly halved its emissions over 30 years.  Reducing emissions by the same amount over the next 30 years will get the UK very close to zero.  However this will be very much more difficult.

A robust net zero target has been recommended for the UK …

A recent report by the UK’s Committee on Climate Change (CCC), the Government’s official advisory body, recommends that the UK adopts a legally binding target of net zero emissions of greenhouse gases by 2050[i], that is remaining emissions must be balanced by removal from the atmosphere.  If the Government agrees, this will be implemented by amending the reduction mandated by the Climate Change Act, from an 80% reduction from 1990 to a 100% reduction.

The target has several features that make it particularly ambitious.  It:

  • sets a target of net zero emissions covering all greenhouse gases;
  • includes international aviation and shipping;
  • allows no use of international offsets; and
  • is legally binding.

This is intended to end the UK’s contribution global warming.  It has no precedents elsewhere, although in France a bill with comparable provisions is under consideration[ii].

Progress to date has been good …

The UK has made good progress so far in reducing emissions since 1990.  Emissions in 2018 were around 45% below 1990 levels, having reduced at an average rate of about 12.5 million tonnes p.a. over the period.  On current trends, over the thirty years from 1990 to 2020 emissions will be reduced to about 420 million tonnes p.a., 47% below their 1990 levels.  Emissions will thus have nearly halved over the 30 years 1990 to 2020, half the period from 1990 to the target date of 2050.

Chart 1 shows how the UK’s progress compares with a linear track to the current target of an 80% reduction, to a 95% reduction and to a 100% reduction.  (For simplicity I’m ignoring international aviation and shipping).  The UK is currently on a linear track towards a 95% reduction by 2050.

Chart 1: Actual UK emissions compared with straight line progress towards different 2050 targets

 

Source: My analysis based on data from the Committee on Climate Change and UK Government.  Data for 2018 is provisional[iii]

The largest contributor to the total reduction so far has been the power sector.  Analysis by Carbon Brief[iv] showed that the fall in power sector emissions has been due to a combination deploying renewables, which made up about of third of generation in 2018, reducing coal use by switching to natural gas, and limiting electricity demand growth.

Industrial emissions have also fallen significantly.  However some of this likely represents heavy industry now being concentrated elsewhere in the world, so likely does not represent a fall in global emissions.  Emissions from waste have also fallen, due to better management.

Reducing emissions will be relatively easy in some sectors …

There are also reasons for optimism about continuing emissions reductions.  Many technologies are now there at scale and at competitive prices, which they were not in previous decades.  For example, falling renewables costs and better grid management, including cheaper storage, will help further decarbonisation of the power sector.  Electrification of surface transport now appears not only feasible, but likely to be strongly driven (at least for cars and vans) by economic factors alone as the cost of batteries continues to fall.

But huge challenges remain …

Nevertheless important difficulties remain for complete decarbonisation.

CCS is identified by the report as an essential technology.  However, as I have noted previously, it has made very little progress in recent years in the UK or elsewhere[v].  CCS is especially important for decarbonising industry.  This includes a major role for low carbon hydrogen, which is assumed to be produced from natural gas using CCS – although another possibility is that it comes from electrolysis using very cheap renewables power, e.g. at times of surplus.  CCS also looks to be necessary because of its use with bioenergy (BECCS), to give some negative emissions, though the lifecycle emissions from this will require careful attention

Decarbonising building heating, especially in the residential sector, continues to be a challenge.  The report envisages a mix of heat pumps and hydrogen, perhaps in the form of hybrid designs, with heat pumps providing the baseload being topped-up up by burning of hydrogen in winter.  I have previously written about the difficulties of widespread use of heat pumps[vi], and low carbon hydrogen from natural gas with CCS is also capital intensive to produce and therefore expensive to run for the winter only.  The scale of any programme and consumer acceptance remain major challenges, and the difficulties encountered by the UK’s smart meter installation programme – by comparison a very simple change – are not an encouraging precedent.

Emissions from agriculture are difficult to eliminate completely, and no technologies are likely to be available by 2050 that enable aviation emissions to be completely eliminated.  This will require some negative emissions to balance remaining emissions from these sectors.

Policy needs to be greatly strengthened …

Crucially several of the necessary transformations are very large scale, and need long lead times, and investment over decades.  There is an urgent need to make progress on these, and policy needs to recognise this.  This includes plans for significant absorption from reforestation, as trees need to be planted early enough that they can grow to be absorbing substantial amounts by 2050.

The UK’s progress on emissions reduction so far has been good, having made greater reductions than any other major economy[vii].  And technological advances in some areas are likely to enable substantial further progress.  However much more is needed.  In particular policy needs to look now at some of the difficult areas where substantial long-term investment will be needed

Adam Whitmore – 22nd May 2019

 

 

[i] https://www.theccc.org.uk/2019/05/02/phase-out-greenhouse-gas-emissions-by-2050-to-end-uk-contribution-to-global-warming/

 

[ii] The CCC report notes that Norway, Sweden and Denmark have net zero targets, but they allow use of international offsets (up to 15% in the case of Sweden).  France has published a target similar to the UK’s in a bill.  The European Commission has proposed something similar for the EU as a whole, but this is a long way from being adopted. California has non-legally binding targets to achieve net zero by 2045.  Two smaller jurisdictions (Costa Rica, Bhutan) have established net zero targets but these are expected to be achieved mainly by land use changes.  New Zealand has a draft bill to establish a target, but eliminating all GHGs will be difficult because of the role of agriculture in the New Zealand economy.

 

[iii] https://www.gov.uk/government/statistics/provisional-uk-greenhouse-gas-emissions-national-statistics-2018  The change from 2017 to 2018 is applied to the data series from 1990 produced by the CCC (the two data series differ very slightly in their absolute levels).

 

[iv] https://www.carbonbrief.org/analysis-uk-electricity-generation-2018-falls-to-lowest-since-1994

 

[v] https://onclimatechangepolicydotorg.wordpress.com/2018/04/25/a-limited-but-important-medium-term-future-for-ccs/

 

[vi] https://onclimatechangepolicydotorg.wordpress.com/2015/05/18/reducing-the-costs-of-decarbonising-winter-heating-needs-to-be-a-priority/

 

[vii] https://onclimatechangepolicydotorg.wordpress.com/2017/05/09/uk-emissions-reductions-offer-lessons-for-others/