DECC model highlights inconvenient energy truths

First published in Energy World, 1 June 2011.

For those of us with an anorak in the closet, the government’s new online energy planning tool, the 2050 Pathways Calculator, has provided hours of perplexing fun. The goal is to cut British climate emissions 80 percent by mid-century while keeping the lights on, through choices about levels of demand, modes of transport, generating technologies and so on. But this is no game.

The Department of Energy and Climate Change clearly intends us to confront the many uncomfortable trade-offs inherent in our energy predicament, but two conclusions in particular are inescapable and troubling.

First, abandoning nuclear in the wake of Fuskushima would have major consequences for the amount of fossil fuel back-up capacity we would need, and for our chances of achieving real and sustainable cuts in emissions. Second, almost all the scenarios that work depend on unsustainable use of the countryside or unproven technologies.

At first I was encouraged by how easy it is to decarbonise the electricity supply by around 2030. I chose the lowest option for new nuclear (level 2 out of 4), and renewables targets that are very ambitious but within the bounds of political possibility (mostly 3s, some 2s). When you cut out nuclear altogether, the good news is that it makes little difference to the emissions reductions achieved, but the bad news is you need almost 50 gigawatts (GW) of back-up gas generating plant to keep the lights on when the wind doesn’t blow.

To put this in context, UK peak demand is about 60GW on a cold winter’s evening, so that level of backup means building almost an entire ‘spare’ generating industry, at vast expense, which would sit idle for much of the time. It would also require a huge gas storage network to supply those plants at short notice, capable of holding and releasing an entire week’s gas supply in real time – the stress test is for five consecutive windless days in a cold winter. Britain has notoriously low levels of gas storage, and can only release about 10% of current demand on any given day.

There is an alternative to nuclear baseload, but it also comes with huge drawbacks. Back-up capacity can be reduced to a more manageable 17GW if we introduce some coal fired power stations with carbon capture and storage (CCS). However, CCS plants – if they are ever commercialized – will be 90% efficient at best, meaning 10% of the emissions will still escape. So the more CCS plants we build, the harder it becomes to hit the emissions target.

The only way to solve this is to burn a lot of wood along with the coal, which has the effect of making the CCS plants carbon neutral, since we would be burying CO2 captured from the atmosphere by the trees. But in the DECC model this requires an area the size of Wales devoted to biomass forestry.

Another reason the model cannot hit its targets without commandeering vast swathes of countryside is the persistence of emissions from oil.

For the sake of argument I ticked all the most optimistic assumptions about demand-side response: all cars, vans and public transport are electric by 2050; so is home heating; half of all freight goes by rail; people wear woolly jumpers and take the bus. As a result oil consumption halves by mid century. A DECC official described my assumptions as ‘heroic’, but they may become compulsory, if global oil production soon peaks and goes into decline as I and many others expect.

However, by mid century dwindling oil supplies are still used in sectors harder or impossible to convert to electricity – aviation, shipping, road freight and industry. Even with the most optimistic assumptions about demand and renewable electricity supply, the maximum emissions cut is 78%. The only way to hit the 80% target is to turn over a land area the size of Wales to biofuel production.

If we want biomass for CCS and biofuels to back out the remaining oil consumption, the total land area is twice the size of Wales. This is unsustainable for two reasons.

The first is food security. Britain already produces only 60% of its food, and devoting 10% of our land to biofuels could only make our import dependency worse. With the pressure on global food supplies and prices rising remorselessly, we would simply swap one problem for another. The selfish solution would be to import an equivalent amount of biomass from abroad, but either way, the claimed emissions reductions are likely to be illusory.

That’s because of something called ILUC, which officially stands for Indirect Land Use Change, but it could equally well mean Inescapable Law of Unintended Consequences. Either way, ILUC happens when biofuel production displaces food crops, pushing farmers elsewhere to clear more forest or grassland to grow food. That land use change releases huge amounts of carbon in a single burst, outweighing any subsequent emissions reductions that might have been achieved by the biofuels.

A recent report from the Institute for European Environmental Policy found that the ILUC impact of achieving the EU’s target of 10% renewable transport fuels by 2020 would require replacement food production on a land area somewhere between the size of Belgium and Ireland, equivalent to putting up to 26 million additional cars on Europe’s roads. So the emissions reductions achieved by CCS biomass co-firing are likely to be illusory – or worse.

This suggests we should abolish the EU and UK biofuels targets, and in the model, set the biofuel buttons to zero. But that still leaves the problem of how to hit the emissions target and eliminate the remaining oil consumption. From here on the ‘solutions’ are increasingly sketchy.

In the model the only other way to hit the emissions target is to ramp up a deus ex machina solution called geosequestration. Unlike carbon capture and storage (CCS) for coal and gas fired power stations, this technology would suck CO2 directly out of the atmosphere, for burial or use in construction materials. However, the technology is in its infancy, and if it is ever commercialized would mean tens of thousands of freestanding units – each about the size of an upturned shipping container – along with vast amounts of power. The amount needed in this scenario would take 10 Sizewell B nuclear stations, according to DECC, which wouldn’t come cheap.

As for replacing the most stubborn parts of oil demand, there are some encouraging developments. Jet fuel is soon to be produced from organic waste, and possibly from algae grown in saline ponds on non-productive land. But these pale against the scale of the task.

And as for the problem of all that gas-fired back-up capacity, I am convinced it will eventually be rendered unnecessary, as the intermittency of renewables is eliminated by a Europe-wide supergrid. But that is a 20 year job at least.

DECC has done a good job of illustrating the intractability of the problem. Now all it needs to do is come up with the policies to solve it.