Pure Plant Oil (PPO), a diesel substitute produced from crushed rapeseed, sounds like an environmentally benign and cheap vehicle fuel but is this actually the case? A recent study by CE for SenterNovem shows that a number of qualifications are in order. The following main conclusions were drawn:
- PPO from rapeseed can only be used as a vehicle fuel after the engine has been converted to handle 100% PPO, which at present is only feasible for a limited range of vehicles, viz. those with indirect injection engines or central injection pumps.
- Using PPO would reduce vehicle greenhouse gas emissions by an average of about 30%. Depending on per-hectare rapeseed yields, field emissions of nitrous oxide and the production technology employed, this figure might be as much as 65% or, alternatively, as low as minus 15% (i.e. more emissions). These results are based on the biodiesel data cited on the UBA website.
- Emissions from PPO-fuelled vehicles cannot yet be estimated with any degree of accuracy, as measurements are still too sparse to draw any general conclusions. It can be stated, however, that such vehicles will definitely have significantly lower per-kilometre emissions of particulates and NOx.
- Using PPO as a vehicle fuel is also an expensive route to climate control. PPO production costs are currently 2-3 times higher than those of diesel, even without the additional costs of engine conversion. This is what makes using PPO such an expensive option, with an average price tag of around € 950 per tonne CO2. For comparison: in Dutch energy conservation policy the cost threshold for abatement measures is € 50 per tonne CO2 avoided.