The challenge of deep decarbonisation

This is roughly the talk I gave in the neighbouring village of Grindleford about a month ago, as part of a well-attended community event organised by Grindleford Climate Action.

Thanks so much for inviting me to talk to you today. It’s great to see such an impressive degree of community engagement with what is perhaps the defining issue we face today – climate change. What I want to talk about today is the big picture of what we need to do to tackle the climate change crisis.

The title of this event is “Without Hot Air” – I know this is inspired by the great book “Sustainable Energy without the Hot Air”, by the late David McKay. David was a physicist at the University of Cambridge; he wrote this book – which is free to download – because of his frustration with the way the climate debate was being conducted. He became Chief Scientific Advisor to the Department of Energy and Climate Change in the last Labour government, but died, tragically young at 49, in 2016.

His book is about how to make the sums add up. “Everyone says getting off fossil fuels is important”, he says, “and we’re all encouraged to ‘make a difference’, but many of the things that allegedly make a difference don’t add up.“

It’s a book about being serious about climate change, putting into numbers the scale of the problem. As he says “if everyone does a little, we’ll achieve only a little.”

But to tackle climate change we’re going to need to do a lot. As individuals, we’re going to need to change the way we live. But we’re going to need to do a lot collectively too, in our communities, but also nationally – and internationally – through government action.

Net zero greenhouse gas emission by 2050?

The Government has enshrined a goal of achieving net zero greenhouse gas emissions by 2050 in legislation. This is a very good idea – it’s a better target than a notional limit on the global temperature rise, because it’s the level of greenhouse gas emissions that we have direct control over.

But there are a couple of problems.

We’ve emitted a lot of greenhouse gases already, and even if we – we being the whole world here – reach the 2050 target, we’ll have emitted a lot more. So the target doesn’t stop climate change, it just limits it – perhaps to 1.5 – 2° of warming or so.

Even worse, the government just isn’t being serious about doing what would need to be done to reach the target. The trouble is that 2050 sounds a long way off for politicians who think in terms of 5 year election cycles – or, indeed, at the moment, just getting through the next week or two. But it’s not long in terms of rebuilding our economy and society.

Just think how different is the world now to the world in 1990. In terms of the infrastructure of everyday life – the buildings, the railways, the roads – the answer is, not very. I’m not quite driving the same car, but the trains on the Hope Valley Line are the same ones – and they were obsolete then! Most importantly, our energy system is still dominated by hydrocarbons.

I think on current trajectory there is very little chance of achieving net zero greenhouse gas emissions by 2050 – so we’re heading for 3 or 4 degrees of warming, a truly alarming and dangerous prospect.

What are these greenhouse gases, and where do they come from? The two key gases are carbon dioxide and methane, in that order of importance. The biggest (but not the only) source of carbon dioxide is our energy system.

It is difficult to overstate the degree to which our civilization depends on cheap and abundant energy; that energy still, predominantly, comes from burning fossil fuels, producing carbon dioxide.

What’s our personal energy budget?

Let me talk now about some numbers. I know that energy units can be confusing, with talk of terawatt hours, exajoules, and millions of tonnes of oil equivalent. So I’m going to follow the example of David MacKay, and use a single unit, the kilowatt hour, and I’m going to express our energy use in terms of the average amount of energy used in a day by a single person, assuming that the UK’s energy consumption is shared out equally amongst the population.

So I’m going to talk in terms of kilowatt hours (kWh) per day per person. This is the unit our electricity bills come in, so we can express it also in currency. 1 kWh of electricity costs about 12 – 16 pence (depending on what complicated and misleading tariff you have), 1 kWh of gas costs about 4 p. A litre of petrol contains about 10 kWh worth of energy, so energy in the form of petrol costs about 13 p a kWh.

What’s our share of the UK’s energy use? On average, it’s about 90 kWh per person per day [1]. And where does that come from? The problem is that a bit more than 80% of that comes from burning fossil fuels, directly releasing carbon dioxide into the atmosphere. In fact, 55 kWh is directly burnt oil and gas – gas for heating and hot water, oil for petrol and diesel in cars and trucks. And yet more gas is burnt to generate electricity.

This is a really important point. We sometimes hear the government boasting that we’re achieved a target of 50% low carbon power, and on windy autumn days we sometimes reach a third of our power coming from wind.

But we must remember that here we’re talking about electricity, and the electricity we use is a relatively minor fraction of the total energy we use.

Roughly speaking, most of the energy we use can be divided into three boxes: fuel for driving around, gas for heating our houses, and electricity for all our appliances and gadgets – and our share of the UK’s commercial and industrial processes.

So out of the 90 kWh per person per day total, 35 kWh is used in petrol and diesel for cars and trucks, 21 kWh for gas to heat houses and hot water, and 30 kWh for the inputs into power stations to produce the 14 kWh of electricity we use.

Is that it?

Alas, no. There are two other big things that are left out of the national statistics.

Firstly, there is aviation. This accounts for about 7% of our GHG emissions as a nation. But it attracts a lot of attention, for a couple of reasons. It’s growing fast, it’s very difficult to see how to decarbonize it, and its distributed very unevenly. Most people don’t fly at all, but a few people fly a lot. So for a well-off individual, it’s easy for it to be the dominant contribution to someone’s carbon footprint.

One intercontinental trip a year can add 30 kWh/day to your total energy consumption; a winter trip to Malaga will add 6 kWh/day. It’s the distance you go that matters.

Secondly, there’s the stuff we buy. It costs energy – sometimes a lot of energy – to make stuff, so we ought to count the energy used to fuel our material consumption in the totals.

The figures I quote above do include UK industry – the problem is that we import much more stuff than we export. In effect we’ve effectively offshored much of our greenhouse gas production.

Materials like steel, cement and aluminium depend on the use of fossil fuel derived energy; so does the food we eat.

The cement works is a big landmark in the Hope Valley, and it’s a major producer of greenhouse gases. Making cement has a double impact – heat from fossil fuels is needed to power the process of making the stuff, but the chemistry of that process also produces carbon dioxide directly. The 1.5 million tonnes of cement a year the plant makes leads to the release of about 1.35 million tonnes of carbon dioxide – that’s about 0.4% of the total emissions for the whole UK!

Staple foods like wheat and rice depend on artificial fertilizer produced from fossil fuel energy by the Haber-Bosch process – on some estimates, without this artificial fertilizer, between a third and half of the world’s population would starve.

Our electronic devices – our laptops and smartphones – are particularly energy intensive to produce. But there’s another, even less well appreciated way in which our digital lifestyle has a big carbon footprint – the servers which power the “cloud”, where all those cat videos live, consume a huge and fast increasing amount of energy. Worldwide, the production and use of digital devices like phones and computers is estimated to have a carbon footprint twice the size of aviation, and this is growing twice as fast.

How much does this all this additional indirect consumption of energy – energy embedded in the stuff we import – add up to? Adding this up is quite difficult, as we don’t know for sure how energy intensive the industries all across the world producing this stuff are.

David MacKay in his book makes a bottom up estimate of the embedded energy in stuff, which comes in at about 40 kWh/day per person. This is possibly a little low – some more recent estimates put it more like 50 kWh/day per person. What we can be certain of is that this embedded energy, in the imported stuff we buy and use, is a really significant fraction of the total energy we use. The UK’s dependence on imported goods amounts to the export of a substantial part of its carbon footprint – but we can’t escape responsibility for the greenhouse gas emissions this leads to.

What can we do about reducing this?

So in round numbers, each individual’s share of the UK’s energy consumption is 90 kWh per day for direct energy use – and 80% of this derives from fossil fuels, and causes carbon emissions. Another 50 kWh per person per day is embodied in all the stuff we buy that’s imported from abroad, where it causes yet more carbon emissions. And if we take the occasional flight that’s going to bump up our averages by a further few 10’s of kWh per day, depending on how far and how often we fly.

What can we do to reduce this? Firstly, we should reduce our consumption of stuff – buy less, mend more, be careful about the use of our electronic devices, switch our consumption to less carbon intensive products – including eating less meat and dairy.

But there’s no escaping that the industrial society we live in makes it difficult to use drastically less energy – we need to get around, we need to heat our houses, we do need agriculture and industry to feed us and provide the infrastructure we rely on.

We can reduce demand, by making our houses more energy efficient, by using less gas-guzzling cars. But to make a big impact, I think we need to follow the recipe David MacKay recommended – electrify everything, and decarbonise our electricity supply.

We’re beginning to see electric cars, for example – we now need use of these to increase by a factor of a thousand or so. For this to happen, we’re going to need to see big falls in costs – mostly the cost of batteries. And we’ll need to create a whole new charging infrastructure. And if we use more electricity for cars, that electricity will have to be generated – perhaps adding another 10 kWh per person per day to the 14 kWh we use now, if all petrol and diesel cars are taken off the road.

Domestic heating is going to be difficult, because so much of our housing stock is old and retrofitting is difficult. What we need here is a massive building programme of new housing – maybe focusing on social housing, which we need anyway, making sure it is built to the right, highly energy efficient standards.

As we switch from burning fossil fuels to using electricity, even more electricity will need to be generated. Including what we need for electric cars, and replacing most industrial and domestic burning of natural gas [2], and even accounting for improvements in energy efficiency, we could easily be talking about doubling electricity generation or more, to 30-40 kWh per person per day or so [3].

How’s our progress towards generating that much low carbon electricity? The last decade has seen a really impressive expansion of solar energy and wind power – especially offshore wind. Yet wind and solar now still only account for 2.5 kWh/person/day.

How much more can we hope for? Optimistic, but achievable, scenarios for offshore wind envisage 5 kWh per person per day by 2030, and tripling solar from 0.5 kWh per person per day to 1.5 kWh.

The biggest source of low-carbon electricity now is nuclear, which supplies 3 kWh per person per day. Most of this capacity will go offline in the next decade as the 1970’s generation Advanced Gas-cooled Reactors reach the end of their operating lives. This loss of low carbon generation capacity will pretty much wipe out of all the gains from wind and solar up to now.

I know this is going to be an unpopular view with this audience, but I don’t think we can decarbonise our energy supply on the time-scale we need without nuclear power – and that means building more nuclear power stations, as well as keeping the ones we have got going as long as possible. Although I think nuclear power is an ugly technology with plenty of disadvantages [4], I don’t think we can do without it given the climate emergency we face. The gap between the low carbon electricity we need – perhaps 25-30 kWh per person per day – and what wind and solar are likely to able to provide is just too big – 6-7 kWh per person per day is a reasonable guess of what could be in place by 2030 [5].

Too many people think that offshore wind and solar are an alternative to nuclear. It’s not a question of either one or the other, in my view: we need every source of low-carbon power we can find [6]. A massive buildout of low carbon generation is needed right now. It’s not happening with anything like enough urgency.

Non energy greenhouse gas emissions

I’ve focused so far on our use of energy, which is the biggest source of our greenhouse gas emissions. But there are other sources, and of these the biggest is in the way we use land, which in the UK accounts for 11% of total emissions. We can make a significant difference by changing the way land is used [7].

There’s a great and positive example here in the Peak District, that my fellow speaker tonight, Peak District National Park Authority Chair Andrew McCloy, has already mentioned. The peat uplands of the Peak – on Kinder Scout and Bleaklow, for example, are really significant sinks of carbon when they’re working well – but over the decades they’ve become degraded, to the extent that they’re actually releasing carbon dioxide, most visibly in the wildfires we’ve seen in recent summers.

Moors for the Future is a great project that is already making a material difference. I remember the Kinder Scout of my youth – or even a decade or two ago – as a black wasteland of fast-eroding peat. But I was up there a couple of weeks ago, and the work that’s been done damming up the groughs and encouraging new vegetation growth is already starting to transform the plateau.

We should certainly let more of our uplands revert to tree cover, hastening that by planting projects. It’s tempting to associate this with “carbon offsetting” – trying to atone for the carbon emissions of flying by planting more trees. I’m a bit sceptical about this – planting trees shouldn’t be a substitute for reducting other emissions – it’s necessary in itself to stop things getting worse.

So, are we going to reach net zero greenhouse gas emissions by 2050?

No, not the way we are going. All the scenarios that suggest we can rely on “negative emissions technologies” which currently remain at the concept stage. We have to get serious about this.

We have got to change the way we live, and we’ve got to build out a new low carbon infrastructure – including power generation, transport systems, low carbon housing. We have to start right now, but it’s going to be a project for the decades ahead.

What can individuals do and what can communities do, in the face of a challenge on this scale? We need a combination of action on the basis of individual choices, and political action on a very large scale, and communities coming together as they’re doing here tonight is the necessary beginning.

A few sources and footnotes

[1] Numbers here come, with some rounding, from the Government’s Digest of UK Energy Statistics 2018, converted into kWh per day per head of population.

[2] It’s possible that some natural gas could be replaced by hydrogen gas, which burns without producing carbon dioxide. The hydrogen would itself be made from natural gas, in a process that itself produces carbon dioxide, but this carbon dioxide would be captured and stored indefinitely underground in depleted gas reservoirs (carbon capture and storage). For more on this, see note 6.

[3] These estimates come from the Committee on Climate Change’s Net Zero technical report. They assume that some gas for heating will be replaced by hydrogen.

[4] See my earlier post Moving beyond nuclear power’s troubled history for the background, and Rebooting the UK’s nuclear new build programme for how we ought to do things better.

[5] An additional issue for an electricity grid that relies very heavily on wind and solar is “intermittency”- the fact that the wind doesn’t blow and the sun doesn’t shine all the time. There are ways of getting round this to some extent through storage and redundancy. Advances in battery technology mean that storage may be able to handle some short term fluctuations – though not (for example) the difference between winter and summer yields of solar energy. But the closer the grid gets to being 100% renewable, the more expensive it will be to mitigate intermittency.

[6] Continuing to use fossil fuels like gas and coal to generate electricity but capturing and storing the carbon dioxide, is another possibility. I’ve explained elsewhere (Carbon Capture and Storage: technically possible, but politically and economically a bad idea) why I think this is unattractive, but we will probably need to use it for things that are very difficult to decarbonise otherwise (like cement-making, and possibly making hydrogen, as in note 2 above).

[7] See Land use: Reducing emissions and preparing for climate change from the Committee on Climate Change.

2 thoughts on “The challenge of deep decarbonisation”

  1. It’s great news, but the important point to keep in mind is the one I keep making – what matters, if we are to achieve the goal of deep decarbonisation, isn’t so much the marginal cost of bringing on another GW of renewable capacity, but the total system cost of decarbonising the whole energy system.

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