carbon limited

In the last post, I argued that we’ve got to strip the carbon out of almost all of our existing stock in order to hit the 2050 target. That’s a huge challenge. Phil Clark summed it up in a comment:

I would consider it a near impossibility to upgrade every old leaky house without some massively radical action.

I completely agree: it’s going to take radical action. But what kind? The picture gets a bit clearer if you take a look at where the carbon is coming from.

Looking at the graph from my previous post, we can take a snapshot of where the emissions will come from in 2050 under a business-as-usual scenario.

The pie chart above shows that of the emissions from houses in 2050, almost 2/3 will come from heat. Electricity, on the other hand, will only make up just over a third of emissions. Without radical action to decarbonise heat, we won’t get anywhere near the 2050 target.

But for some reason, heat doesn’t figure very highly in Government thinking about emissions. Instead, most attention has been focused on decarbonising electricity as embodied by the Renewable Obligation, the Government’s primary mechanism for encouraging uptake of renewables. Sure, there’s talk of a renewable heat incentive, but this ignores the most important step: using heat better.

As John Hutton pointed out in the intro to the Heat Call for Evidence, power stations currently throw away enough heat to meet the needs of every home in the UK. I’m not suggesting hooking up our homes to every existing centralised power station but it shows that we can use our resources a hell of a lot more effectively. And it clearly shows that we need to think beyond “renewable heat”. Why plant even an acre of willow coppice if the heat we need is already being thrown away?

Energy efficiency is an important start but isn’t enough on its own. Once cost effective upgrades have been carried out, we have to look at supplying remaining demand from sources that will drastically reduce emissions.

Addressing hot water demand with solar thermal will help reduce one wedge in the pie chart above. Biomass will play a key role, but it’s no silver bullet. And some heating might come from wind or other renewable electricity, but it’s not a viable strategy on the wider scale because of the sheer volume of heat needed and the decrepit state of the national grid.

In the end the solution will probably include a combination of these measures. Also, and perhaps more importantly, it will include capturing heat where power is generated (whatever the fuel) and waste is incinerated or gasified.

Then, once we’ve identified the heat, we have to start moving it from where it’s created to where it’s needed. For new developments, this might only be a few tens of meters. For existing stock it’s going to be further, in some cases a lot further. But in my view, until we come to terms with this fact, we don’t have a hope of achieving the 80% reduction.

If government is serious about 80% (and legally it has to be), then it must put heat first and start thinking seriously about how it gets delivered.