Grid Enabled Vehicle Efficiency and W-T-W CO2 Emissions Analysis
For conventional vehicles, Well-to-Wheel analysis of vehicle CO2
emissions must also take account of petroleum refining and distribution emissions. For GEVs, account must also be taken of electricity generation emissions and transmission losses. The following table presents details of recent authoritative research into the efficiency of GEVs, comparing them to conventional gasoline and powertrains. It is extremely important to normalise the comparison, by using the same vehicle size and the same (NEDC) drive cycle. The last three rows present our own best estimates of the most accurate figures9
Powertrain Efficiency & W-T-W CO2
It can be seen that based on the latest IEA figures for the average EU electricity generation mix and transmission losses and the most up to date analysis of EV powertrain efficiencies (71% with up to 15% energy recovery from regenerative braking), that a European GEV will produce 56g/km W-T-W CO2 emissions, compared with 194 g/km for gasoline and 160 g/km for diesel vehicles.
It is extremely informative to look at the carbon intensity of electricity generation in different global markets.
Carbon Intensity of Electricity Generation in Global Markets
Normalised global vehicle W-T-W CO2
It can be seen that GEVS will substantially reduce W-T-W CO2 emissions in every major market in the world, with the possible exception of India.
These results are broadly consistent with the findings of the Imperial College study of Techno-economic and behavioural analysis of battery electric, hydrogen fuel cell and hybrid vehicles.
All Electric Range (AER) v PHEV vehicle and battery size
Emissions v PHEV vehicle and battery size
The Royal Academy of Engineering report makes the point that PHEVs are a more cost effective and mainstream solution than EVs.
“An alternative model to the widespread adoption of EVs with their infrastructure requirement would be the plug-in hybrid electric vehicle (PHEV). While this type of vehicle has most of the environmental benefits of an EV, it does not rely on a comprehensive network of recharging points at possible destinations. This means that it could be adopted quickly as a family car or executive car, leaving EVs to achieve initial market penetration as second cars, covering low mileages and thus having little impact on CO2 emissions.”
The report also raises another important point which we address.
“Plug-in hybrids, as their name suggests, still need some where to plug in. The ‘early adopters’ could be to users with off-street parking but, to meet the 80% target, a solution would have to be found for the millions of motorists who park on-street at nights.”
Our solution is to equip the vehicles with approx 4m retractable aerials and 50m of cable on a spring loaded dispenser, (like a garden hose spool placed in the rear wheel cavity). This would allow the cable to be trailed to first floor windows, avoiding any trip hazard from cables on the ground and would provide a secure solution. PHEVs and EVs with an onboard charger can and should be plugged straight into the mains without any intermediate charging units. A 6 kWh battery with 4 kWh usable state of charge would require 1.8 hrs to be re-charged using the standard European 220V 10A domestic grid supply. This solution is being overlooked by general consideration of how best to introduce the ‘electromobility’ urgently required. One of the huge advantages of PHEVs is that no new infrastructure is required. As identified by G. Kendall in the WWF 2008 report ‘Plugged In: The End of the Oil Age’.
“Grid connected vehicle technology – enabling all or part of every journey to be powered by electricity taken from the grid – is available based on existing infrastructure and current technology.”
This approach is practical, low cost and necessary for rapid mainstream adoption of the ‘electromobility’ needed to meet scenarios identified in the Roland Berger (T-T-W) analysis below. Our solution can cost effectively reduce average CO2 emissions to 52g/km T-T-W (88 g/km W-T-W). Hundreds of millions of PHEVs charging at night around the world, can utilise spare generating capacity, which tends to be lower carbon and lower cost than peak electricity generation.
Necessary OECD Europe CO2
9The only element missing from this comparison is weight. EVs tend be about 200kg heavier, but a PHEV would not