EV Energy & Emissions Calculator (light vehicles/cars) Boxed squares below are inputs:
         
  Input/Output Unit Scenario 1 Scenario 2
     
EV inputs Average efficiency Wh per km
  Annual km per car km per year
  Total number of cars number
         
Electricity Supply Total electricity supply (without EVs) GWh per year
  Grid losses % electricity lost between generation and EV
  Carbon intensity of electricity mix g CO2 per kWh of electricity generated
         
Conventional cars Average efficiency km per (UK) gallon
  Carbon emissions from fuel kg CO2 per (UK) gallon combusted
         
KEY RESULTS: New electricity generation for EVs GWh per year
  Impact of EVs on total electricity % increase
  Annual CO2 per EV kg CO2 per year per car (using annual km)
  Annual CO2 per conventional car kg CO2 per year per car (using annual km)
         
Calculator © Grey Cells Energy Ltd. 2017      
Visit: https://greycellsenergy.com      
Questions? info@greycellsenergy.com    
     
Notes:                                  
  Units: 1kWh = 1,000 Wh  
    1GWh = 1,000,000 kWh  
    1 US gal = 0.83 UK gal  
  Emissions: kg CO2 per kWh can be found at sites like this one: http://www.mygridgb.co.uk/ (NB. shows in grams, so divide by 1000 for kg)  
    8.9kg CO2 per US gallon petrol/gasoline combusted (wiki) = 11kg CO2 per UK gallon  
  Energy content: 1 gallon petrol energy content: 35.3 kWh per US gal = 42 kWh per UK gal (en.wikipedia.org/wiki/Gasoline#Energy_content)   
    Prefer diesel? It's about 11% more energy dense by volume than petrol, so ~46-47 kWh per gallon. But CO2 emissions are pretty much the same per volume as petrol. 
  Car sources (reality check!): EV Wh per km, offical figures & motoring website sources: e.g. Nissan Leaf 150 Wh/km; BMW i3 160-190 Wh/km; Tesla S 200 Wh/km  
    Petrol (nextgreencar.com): Fiat 500 118km/gal & 88gCO2/km (offical); BMW 3-series estate 113km/gal & 104gCO2/km  
    NB emissions units: 100g per km = 0.1 kg per km  
  UK car data number of vehicles: http://www.racfoundation.org/motoring-faqs/mobility#a1  
    annual mileage: http://www.racfoundation.org/motoring-faqs/mobility#a24 (convert mile to km: x 1.61)  
  UK other Annual GWh electricity: from National Grid FES (http://fes.nationalgrid.com/fes-document/)  
 
Calculator © Grey Cells Energy Ltd. 2017  
Visit: https://greycellsenergy.com  
Questions? info@greycellsenergy.com