Research into Batteries Will Give Electric Cars The Same Range As Petrol Cars

Li-air batteries are a promising opportunity for electric cars. "If we succeed in developing this technology, we are facing the ultimate breakthrough for electric cars, because in practice, the energy density of Li-air batteries will be comparable to that of petrol and diesel, if you take into account that a combustion engine only has an efficiency of around 30 percent," says Tejs Vegge, senior scientist in the Materials Research Division at Risø DTU. If batteries with an energy density this great become a reality, one could easily imagine electrically powered trucks. The electric car was introduced by Edison as early as 1900. But, as we all know, Henry Ford's vehicle concept with a noisy, smelly combustion engine won the race to become people's most treasured individual means of transport, despite the fact that in principle, the combustion engine is hopeless.

Then, as now, the Achilles' heel of the electric car was the limited energy density of the batteries, which will only sustain short drives. Now – 110 years later – the battery technology, combined with the effect electronics and the electric engine, have come so far in performance, size and price that the electric car is again becoming interesting. The electric car does not pollute locally and it can, if used cleverly, be utilised to introduce more renewable energy into the electricity supply.

Electric cars are the perfect match for a society that has abandoned the use of fossil fuels.

This is why electric cars have been reborn as an important factor in the vision of a society without fossil fuels, and the first electric cars have already hit the roads, albeit in very limited numbers and with very short ranges between recharges.

The advantages of the electric car are first and foremost that it can be integrated into the electricity system and potentially serve as a buffer in the electricity system of tomorrow, where most of our electricity originates from fluctuating renewable energy. Where there is excess electricity from e.g. wind turbines, the electric cars can be charged. When there is a shortage of electricity, some of the power can be returned to the electricity grid. The other major advantage is that, if mass-produced, the electric car could be cheaper to produce than the current cars.

2 tonnes of batteries or 50 litres of petrol

Today, battery packs are expensive and are only able to store a relatively low amount of energy. Researchers all over the world are working to change that. In the current setting, an electric car is no good if you are taking the family on holiday to Lake Garda in Italy. For electric cars to become the consumers' preferred mode of transport, the battery capacity must be significantly increased. In Risø Energy Report 9, page 58, you can read that the energy density in today's batteries is almost two orders lower than that of fossil fuels. This means that a battery pack containing energy corresponding to 50 litres of petrol, would weigh between 1.5 and 2 tonnes.