Considering pure electric cars, we’ll take a look at how ìgreenî they can be, and contrastingly how ìdirtyî they can also be, depending not on the efficiency of the car itself, and its battery, but as an owner based on your geographic location. We’ll look at this strictly in terms of carbon dioxide (ìglobal warmingî) emissions, and not other air pollutants, and we’ll use the UK as a baseline to consider the differing picture in some other countries. In Britain, most current EVs, driven normally, will cover 3 to 4 miles, or 5 to 7 kilometres, on one kWh of the electricity drawn from its battery. To convert that to generated electricity, we must compensate for various distribution losses in the national grid, and those lost in battery charging, which amount to around 30 per cent. So we are thus looking at covering 3 to 5 kilometres per generated kWh of grid electricity, the CO₂ footprint of which is key to its eco credentials. In Britain, a figure of 300g/kWh is a fair figure for grid electricity, averaged over the day, the week, and the seasons, although this figure needs putting into perspective, as we will later. With 300g of CO₂ emitted for every 3 to 5km travelled, that is some 60 to 100g/km, compared with real life figures for diesel cars of around 120 to 200g/km. So EVs are inescapably around twice or more ìgreenî than the best diesels, in terms of carbon dioxide emissions. That is undeniable, and these are average figures for the whole of the UK though, and take your car up to Scotland, where locally generated wind and nuclear electricity (some of which is exported to England!) makes the average grid electricity nearly 100 per cent greener (150g/kWh) than in the rest of Britain, and there’s no argument that EVs are inescapably far cleaner there, on that basis. Take your car to Sweden though, charge it up with electricity that is five times as green as the UK’s average grid electricity, and any EV is ten times greener than any diesel or petrol car!  

At the other extreme, in China, where grid electricity is largely generated in coal-fired power stations, with a carbon count of 900 to 1,000g CO₂ per kWh, the figures swing wildly in the other direction. Plug-in EVs in China are amazingly up to 50 per cent dirtier than petrol or diesel cars! Yes, really! What incentive is there to ìgo electricî in China? Well, substantial state rebates of up to £7,000 to £8,000 per car, and the Chinese electricity is also very cheap, so the whole picture is quite confusing, and dirty. 

Closer to home, the picture in two European countries is disappointing, if not quite as grim as in China and India. Both Germany and Poland still use significant amounts of coal in their power stations ñ Germany’s post-Fukushima 2011 phase out of nuclear power severely set back plans to run down the coal-fired stations. As a result, German electricity is some 50 per cent higher in CO₂ output per kWh than Britain’s, Poland’s even worse. Perhaps it’s a good job plug-in EV sales in Germany are lagging even Britain’s then, since their true green credentials are questionable, and will remain so until Germany’s electricity becomes significantly cleaner.

Back home, Britain has halved its power generation carbon dioxide emissions in around a decade, but unless the National Grid can respond to any significant increased power demands, the green status of plug-in EVs is threatened. At peak times, even now, electricity demand has to be met using the ìdirtiestî gas-fired power stations, which at 500g CO₂ per kWh are over 50 per cent dirtier than the existing grid mix of 300g/kWh ñ the figure we used in our calculations above. Unless we can meet that challenge of increased demand with cleaner electricity, or by effective demand management, the whole proposition of clean, green, electric cars is still questionable.