This is a very important development for the UK energy sector - nuclear currently generates about ~21 % of UK electricity, but a significt fraction of existing supply will retire soon - creating a gap in our low carbon electricity supply 1/
The scale of this lost capacity in electricity supply is not small - and the immediacy of this timeline is clear an apparent, with much of the advanced gas reactor (AGR) fleet retiring by 2030, and only Sizewell B running past this point 2/
Why do we care about nuclear in the low carbon mix?

Often energy advocates will speak about proxy goals - eg more renewables, more battery storage, demand management.

To combat climate change - we can rely on proven technology to limit our emission of CO2 & grow new tech too 3/
Electricity is one of the easiest forms of energy supply for us to decarbonise - and we know that nuclear can make a lasting and sustained impact in this domain, and compliment other low carbon approaches 4/
We are already building Hinkley Point C - I visited there a while back to see the impressive programme of building, and the learning being transferred from the first reactor complex to the second, as well as learning from other incomplete and completed EPRs internationally 5/
Why does this matter re: the Sizewell C announcement?

A major issue for Hinkley Point C was the financing of nuclear power, driven (at the time) by nervousness of investors - building a second EPR reactor pair in the UK massively reduces the financial risk & boosts confidence 6/
The financial argument & improved confidence is really important in the fight to address climate change - the National Audit Office dug into the historical context of the Hinkley Point C project and highlighted how we got to where we were 7/
The climate is different for Sizewell C - EdF are exploring other financial methods and trying to level the financial playing field - this changes economics significantly & highlights that repeat building helps us in our fight against climate change 8/
The short story of the strike price - with a different financial structure, afforded due to increased investor confidence and fairer access to financial markets (e.g. confidence with pension funds and other investors) - is that the price will drop 9/
Sizewell C is well placed to benefit from this, as the confidence is built from re-using much of the infrastructure and workforce from Hinkley Point C, as well as use of modern engineering approaches (eg building inside), and replicating the EPR design 10/
Though I repeat - the scale of this challenge is very easy to overlook. Sizewell C can supply c. 8% of UK supply, making Hinkley Point C and Sizewell C not quite fill the shortfall of the upcoming closuring of nuclear reactors in the UK 11/
Our societal needs for low carbon electricity supply will also change a bit if we consider decarbonisation of technology beyond electricity, eg heating, manufacturing, transport, and in many cases this will use electrification (e.g. as week with lorries and cars)

So in addition to the exciting news regarding Sizewell C, we must look forwards and consider more renewables and the likely need for more nuclear power (eg small modular or next gen nuclear) to manage humanities thirst for electricity 13/
And as I suspect some folks may come to this thread and kick off empty rhetoric, one important aspect in all of this story is that the splitting the atom, in a nuclear fission reactor, is very effective. 14/
To reiterate this point - the efficiency of nuclear fission reduces the landmass occupied by electricity generation substantively, & many other benefits to compliment an energy system

(This XKCD comic looks extremely dated now that we are all very familiar with log scales…) 15/
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