Should South Wales see red? A review of NGESO’s new App


NationalGridESO have just released their own app – it looks pretty and has some nice features for low-carbonistas in Great Britain. I especially like the records page, which has been triggered recently for both “Max No Coal” Hours and “Max Solar” MW. The key content though is grid carbon intensity, which has been available for some time via third party apps.

A while back NationalGridESO got together with Environmental Defense Fund Europe, University of Oxford Department of Computer Science and WWF to develop a carbon intensity forecast for the GB Grid. The collaboration (“”) uses machine learning and a model of the GB power system to forecast carbon intensity, with the excellent aim of giving users – via an Open API – the ability to time their power consumption to minimise climate impact. This feeds both NGESO’s new app – and the third party ones.

The collaboration estimates and forecasts the average carbon content of grid electricity. For true energy geeks, the “marginal” carbon grid content would be a more relevant tool to optimise demand loads: basing the decision not on all the power plants that are already running (because most of them will run anyway) but what additional plant might need to run slightly more or slightly less to satisfy the controllable demand. However, assessing the marginal plant is a subjective matter, and it’s also true that marginal carbon content will tend to be low when average content is low. But perhaps most importantly it’s far easier for people to relate to average carbon content – and the evidence from the early apps is that it’s been really popular, which is fantastic.


A far more debatable element of the collaboration – which features heavily in the new app – is dividing GB into regional chunks, each with its own carbon intensity.  In lots of ways this isn’t helpful.

Firstly, whilst regional averages are often very different, the marginal plant – which is the thing that really matters – is nearly always the same for the whole country. So turning on some extra washing machines in South Wales has the same impact as turning on some in Kent. Both might actually result in a power station being turned up slightly in Yorkshire. There are relatively few constraints in the national system, and most of them aren’t active most of the time. (Though Orkney with limited connection to the mainland and surplus renewable power is an honourable and frequently constrained exception, and possibly permanently deserves its own carbon intensity).

Secondly, as a matter of principle, consumers all over the country have paid communally for the transmission system – including some huge new investments aimed at avoiding constraints – and for renewable subsidies like the Renewable Obligation, CFDs and FITs. Indeed they also pay equally for the NationalGrid ESO to balance the national system and alleviate any constraints that remain. So it seems a bit wrong to tarnish consumption and consumers in the areas that host fossil fuel plants which are used by the country as a whole. Unfortunately I have seen many comments on social media like “A bad day to live in South Wales” when those plants are running for the benefit of everyone – so it does seem that the consuming public are understandably confused by the locational signal that appears to be given. Maybe NationalGridESO should only turn on the regional carbon intensity readings for a particular area when there is an active constraint – which would mean that the public could respond and actually help alleviate the constraint? That would make a nice app into a fantastic one.

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