Road transport
The main ways to reduce carbon emissions from road transport are:
Vehicle design:
- for example improving aerodynamics, reducing weight and introducing low rolling resistance tyres.
New types of engine
- High efficiency internal combustion engines: Improving the efficiency of petrol and diesel engines (e.g. using turbo chargers to allow smaller engines to be used).
- Hybrids: Recovering the energy from braking normally lost as heat to power the car when it accelerates (typically using a battery).
- Electric: Powering the vehicle using electricity, which allows emissions to be reduced if the electricity is from low carbon sources.
- Fuel cell: Using hydrogen to power vehicles using fuel cells. This reduces CO2 if the hydrogen is from a low carbon source.
Biofuels
- Sustainable biofuels can be a lower carbon alternative to petrol and diesel The engines of conventional vehicles need to be tuned to run on pure biofuels, but a blend of biofuels and fossil fuels can be used in existing vehicles and still reduce overall emissions.
Traffic management
- Introducing regulations such as road pricing can encourage people to drive less and to switch to lower carbon transport; the right regulatory incentives and rail infrastructure could also reduce the amount of freight carried by road.
There are a number of technical hurdles to overcome to bring the less conventional technologies to market. For example, both electric and fuel cell vehicles require new infrastructure to be developed for refuelling / recharging. Furthermore, the cost of the technology and the range and reliability of the vehicles will have to be improved in order for them to be widely adopted.
Aviation
Reducing emissions from aviation requires new technology and regulation to be introduced. However, there are significant challenges with both approaches.
Whilst the efficiency of aircraft can be enhanced by improving aerodynamics, reducing weight and introducing more efficient engines, finding an alternative to hydrocarbons is a huge challenge as passenger aircraft require very high energy densities which are unlikely to be available from batteries or fuel cells. Advanced biofuels are therefore one of the best opportunities for reducing emissions from aviation.
A further opportunity for reducing CO2 emissions is through improving operational efficiency of aircraft by increasing the number of passengers per plane, optimising routes, and improving air traffic management.