Mackay / DECC 2050 pathways calculator

Nobody has claimed this yet.

David Mackay and a team at DECC (including @tamc) created an f/oss pathways to 2050 calculator whilst at DECC in ~2011/2013. This was updated in 2020 at BEIS.

This looks very interesting. Would like to know how up to date this is, what the source code/model looks like ad whether it can be reused.

**NB: this is a UK calculator which led to many other countries doing this. Plus a global calculator http://www.globalcalculator.org (last updated 2015)**

## Tasks

* [x] Find out the status of this **DONE. See notes below. Key point is there is an updated version of this from 2020**
* [ ] Find the source code (not just excel file) for the 2020 model
* [ ] Analyse the model / source code (the excel file?)
* [ ] ...

## Research

McKay carbon calculator (latest version, published 2020): https://www.gov.uk/guidance/carbon-calculator

> The MacKay Carbon Calculator provides a model of the UK energy system that allows you to explore pathways to decarbonisation, including net zero by 2050.
>
> Using the MacKay Carbon Calculator, you can create pathways to find out how we might reduce the UK’s greenhouse gas emissions to net zero by 2050 and beyond. You choose your ‘levels of ambition’ for decarbonising different parts of the energy system, and the calculator then shows how your choices affect UK emissions expressed as ‘carbon dioxide equivalent’ (CO2e).
>
> ...
>
> There are 2 online versions of the calculator, a universal version called My2050 and a detailed version.
>
> * open [My2050](https://my2050.beis.gov.uk/)
> * open the [detailed version of the calculator](https://mackaycarboncalculator.beis.gov.uk/)
>
> Both versions contain levers of decarbonisation, 15 in My2050 and 45 in the detailed version. You select your level of ambition of decarbonisation effort using the levers, ranging from Level 1 - minimal effort, to Level 4 - maximum effort. Popup descriptions explain what the levels represent in terms of behavioural change or infrastructure investment. We will publish a user guide for the detailed version here shortly.
>
> The calculator results are based on scientific data. This Excel spreadsheet provides more information about the model used by the online versions of the calculator:
>
> [MacKay carbon calculator (Excel version)](https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/940672/Excel_MacKay_Carbon_Calculator_v198.xlsm) (XLSM, 13.4MB)

### Old stuff

Official gov page: https://www.gov.uk/guidance/2050-pathways-analysis

> This guidance was withdrawn on 29 April 2021
>
> This page relates to the original UK 2050 calculator launched in 2010, when the UK target was for an 80% reduction in greenhouse gas emissions by 2050.
>
> In 2020, BEIS launched an updated 2050 calculator, the MacKay Carbon Calculator, which can be used to create pathways to net zero

Old app and code

* App (old one from 2013 i think): http://2050-calculator-tool.decc.gov.uk/#/home
* https://github.com/decc/twenty-fifty - old repo
* https://github.com/decc/twenty-fifty-new-look - new repo (last updated in 2015). "The source code for the new look version of the 2050 calculator"


Start with the 2020 MacKay Carbon Calculator guidance, its linked XLSM model, and the older decc/twenty-fifty and decc/twenty-fifty-new-look repositories. Trace whether source code for the 2020 model is available, analyse the model or Excel file, and document whether it can be reused.

Written by the indexing model from the issue text.