The last 20%

In the last 24 hours we have heard much from the G8 meeting in Italy on climate change as world leaders debate reduction targets for developed countries. Whilst they seem unwilling or unable to agree on much of anything for the near term (although in fairness most of the G8 countries have or are about to have a near term target – they are just all different), they have managed to agree on an 80% reduction in emissions for their economies by 2050.

But it raises an interesting question – can we actually reduce emissions by 80%?

In 2007 the EIA reports that total US GHG emissions were 7419 million tonnes, including international marine and aviation bunkers. Without getting into the detail of a 1990 or 2007 baseline (but it is important), let’s assume that US emissions in 2050 must be 1484 million tonnes, or an 80% reduction from 2007. I will also assume that we have long passed the point of international offsets, given that the rest of the global economy will be under tight CO2 regulation as well.

So the scramble for the last 1.5 billion tonnes is on. To make it easy for everyone else I will assume two things – firstly that the power sector is at zero emissions and second that the commercial and residential sectors only use electricity. Neither of these will be easy to achieve in just 40 years, but you will see in a minute why it becomes essential.

There are many sources of GHG in the economy other than fossil fuels. There is methane from agriculture and human waste, various other gases leaking out of our cars and old appliances in the garage, landfill methane, N2O from agriculture – the list goes on and on.

Then there are the fossil fuels that we have all come to depend on. One of the great features of a gallon of gasoline, jet fuel or diesel is the huge amount of stored energy we can get from it. Whilst we may be able to get around this with advanced battery technology in cars, it is hard to imagine anything else powering an A380 twin deck airliner. We may of course be able to synthesize these fuels from bio-sources.

So, just to put some numbers out there and I will be the first to confess this is just “back of the envelope stuff”, we end up with a transition that looks something like this (the 2007 breakdown is approximate):

What we see from all this is that some huge changes have to take place – apart from the power and buildings sector. Road transport (fossil derived)gasoline effectively vanishes but some diesel remains for large trucks and industrial equipment (e.g. diggers). Big industry has to reduce by about 70% which means finding new ways to heat things like blast furnaces. Sectors such as cement and lime are going to have to use technologies such as CCS, but with plants having very long lifetimes and the processes being relatively simple, how much uptake of advanced technology might we really see from such facilities? Some certainly, but an 80% reduction is unlikely.

It would be good to get some comments from the agricultural side – because in my numbers above I imagine that 80% reductions just won’t happen. Are we really going to be able to change methane releases from cattle and capture all the methane from rotting waste products?

I saw a presentation on aviation today and it looks very hard to make huge reductions. Whilst there are still big efficiency gains to be made as we replace fleets with 787 type planes and beyond, it looks like liquid fuels are here to stay. But bio may play a bigger role than the industry can forsee today.

So that is the picture looking out to 2050 – a completely different economy to the one we see today and a real scramble to claim space for those remaining emissions.

Of course, nobody is talking about 2060 when we might need a 90% reduction. Or 2070 . . . . . ! That is when we will really need technologies such as CCS in combination with bio-processing such that we end up with net sequestering (negative CO2) industrial processes.