50% Emissions Drop from GB Power: How?

It’s easy to focus on single solutions to questions in any market, particularly if that solution is one you provide. However it’s important to recognise that there may be other ways to address a market need too – sometimes they’ll compete but in many cases they’ll coexist.

Reducing carbon emissions is one market need that is best addressed through multiple approaches. So in this article I want to briefly examine some recent data which provides interesting lessons and implications in this regard. The numbers I’m using were recently published by Enappsys in their excellent 2016 Summary Report. They provide data for electricity generation in Great Britain (GB, i.e. the “mainland” UK, excluding Northern Ireland) covering the time period 2008 to 2016.

While these specific numbers relate to GB, of course the same principles and conclusions will apply elsewhere.

Here’s the overall picture in one chart,


Figure 1: The Evolving GB Electricity Generation Mix


Generation in TWh is on the left-hand vertical axis, with the changing fuel mix stacked up in the coloured areas. You’ll notice that the topmost of these coloured areas – in light green – is one that I’ve marked as “Reduction”. In other words, total electricity generation in GB has gone down over the period, with that light green area indicating how much lower it is than it was in 2008. (In fact electricity generation within GB has gone down more than that: you’ll notice more imports too).

[On the far right I’ve boxed in a rough idea of the installed capacities of the various generating sources. I’m not going to read anything into those here, so it’s just to give you a rough feel for what levels of capacity are contributing which amounts of energy to the GB mix. They aren’t in the Enappsys summary, so blame me, not them, if you object to them! – I’ve just used the most recent numbers I could quickly find and rounded them].

Changing carbon emissions (from electricity generation) are shown by the black line. This refers to the right-hand vertical axis, which I’ve scaled relative to the size of emissions at the starting point of 2008.

Figure 1 shows that carbon emissions from power generation are half what they were in 2008.

In fact, given that they didn’t change much at the start of the analysed period, they are roughly half what they were as recently as 2012. That sounds like a great achievement!

So, how has Great Britain done this and can it keep it up?

Bearing in mind that imports are not allocated any emissions value, the two fossil fuel sources are dominating: coal and gas.


Figure 2: The Major Carbon Emissions Sources

It’s evident from both this chart and the previous one, that the contribution of gas dropped for a few years but is similar now to where it started. Both charts also show that policy driving coal from the mix – notably via a carbon price floor – has been particularly helpful in carbon reduction (with an acceleration of this in 2016).

Here’s how the electricity mix has changed overall in the whole period. The bars stack up things that have increased (positive numbers) from the left, in order of size, then balanced by things that have reduced (negative numbers) towards the right. The scale is TWh.


Figure 3: The Changing GB Electricity Mix, 2008 to 2016

All the low-carbon sources have increased. Gas has gone down slightly and coal has collapsed.

So, no surprise: we can see that replacing generation from hydrocarbons with generation from low-carbon sources has been effective in lowering carbon emissions.

However this chart also illustrates that the biggest single change has been “Reduction”. (A positive change in demand reduction means demand has gone down).

The removal of coal isn’t just offset by new sources: comparing 2008 to 2016, there’s nearly 38 TWh of electricity that hasn’t been generated at all – very much a zero-carbon resource! In fact this demand reduction has been a bigger change than the growth in any of the other individual generating sources. It has reduced emissions without requiring their investment, operating costs or other impacts (visual, grid extension and so on).

If I plot the same chart starting from 2012 (which we can see from Figures 1 & 2 is the point from which carbon has really shrunk), there’s a similar outcome:


Figure 4: The Changing GB Electricity Mix, 2012 to 2015

(You’ll notice I’ve plotted this for the period 2012 to 2015 – don’t worry, we’ll come back to the last period through to 2016!)

Between 2012 and 2015, carbon emissions from power generation dropped by a third. Gas, hydro and nuclear remained essentially unchanged. So this is a clear story of replacing coal generation with a mix of demand reduction – still the largest individual contribution – and domestic renewable power generation. Plus imports (are they really carbon-free? That’s a discussion for another day…).

The change between 2015 to 2016 is completely different.


Figure 5: The Changing GB Electricity Mix, 2015 to 2016

Carbon emissions from electricity generation dropped by over 20% in just this one year!

However this was not dominated by demand reduction or extra low/zero-carbon generation. It was driven by a straight fuel shift: from coal to gas. That shift – and its outcome – will be familiar to readers from the US.

So if carbon reduction is a key and urgent objective, then some markets will find that fuel-shifting from coal to gas is one of the quickest ways to achieve it (even if, in the longer-term, there’s a preference to get rid of gas from the mix too). That’s the idea of gas as a “bridge fuel”.



We started by asking, in relation to emissions from power generation, “how has Great Britain done this and can it keep it up?”

The answer to the first part of the question is that it’s not been down to one single thing. It’s been a result of three important factors in combination:

  • demand reduction,
  • new renewable energy
  • fuel-shifting coal to gas.

Without all these mechanisms in combination, the result would have been far less impressive.

What about the second part of the question? How can GB continue reducing emissions from power generation?

Well, shifting from coal to gas doesn’t have much further to go. In fact, shifting from coal to anything has almost run its course – just look back at Figure 1!

When coal has gone from the mix, to stop burning hydrocarbons we’d need to focus on gas. Renewables obviously offer a desirable set of alternatives, but the rates of change evident in Figure 1 suggest this will be a long-term transition requiring a lot of new capacity. Certainly they don’t offer the “quick win” we’ve seen through the rapid reduction in coal use in recent years.

So I expect emissions progress to slow.

There are also issues of system flexibility to consider in getting rid of gas: its responsiveness provides a good foil for the variability of wind, for example. Without doubt, the growth of storage, smart demand shifting, interconnection and other solutions for integrating renewable power at scale are going to increase in importance.

Another long-term option, but certainly not a quick win – and for some commentators an “expensive lose” – is to replace some of our gas usage with low-carbon nuclear. What else could drive the UK government’s enthusiasm for the hugely-subsidised £18b Hinkley Point project?

But don’t forget demand reduction!

Here’s a government forecast of electricity demand going forward:


Figure 6: Future UK Electricity Demand?


If this proves correct, reductions in the UK’s need for electricity are set to be reversed; with a 20% increase by 2035. (The chart comes from here – no surprise that it’s part of the UK government’s explanation of their case for new nuclear).

We’ve seen how important demand reduction has been to the country’s carbon performance in the past few years. It’s provided 50% more zero-carbon gain than the building of 15GW of wind.

Combine this with how much harder continued progress becomes once we’ve removed coal from the mix, and it really will be crucial to make sure that Figure 6 proves to be WRONG. Integrating greater capacities of renewable power supply is vital, but I suspect it won’t be enough on it own, in the short and medium term, however smartly we do it.

It’s hard to simply build our way to a low-carbon future.

While it might not be as exciting as investing in and building shiny new generation projects, continued innovation to avoid building them in the first place is going to prove equally vital!

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