Name: GB Grid CO2
Author: JoeHartley

A widget to display the present and forecast carbon dioxide (CO2) emissions of electricity generation on national grid in Great Britain.  

Inspired by https://shouldibake.com/ and https://grid.iamkate.com/, I wanted a way to quickly see this information on my watch. To be able to plan to use electricity when the carbon intensity of the grid is low when possible. The carbon dioxide emission form electricity generation vary greatly as renewable wind and solar production changes, shifting demand to times with lots of renewables could be a small part to play in reducing global warming. 

Data is provided by https://carbonintensity.org.uk/ (the forecast data sometimes goes wrong. e.g. missing forecast data or unrealistic solar forecast. This is out of my control)

Up/down buttons change between views: 
 - Main View 
    - Present carbon dioxide emissions in grams of CO2 per kWh. 
    - Description of carbon dioxide emissions (low/medium/high/very high).
    - Meter of emissions around edge of display from 0 to 400gCO2/kW. 
    - Graph of forecast carbon dioxide emissions for new 24 hours.
- Energy mix view
    - Pie chart of present energy generation mix around edge of display, with significant sources labelled with %.
    - Graph of forecast generation mix for low carbon generation types (Wind/Solar/Hydro/Nuclear). Graph colours match pie chart/labels.

Start button triggers reload of data, also triggered when opening widget. 