Concerns over fuel prices and climate change are pushing Germany, a nation of automobile enthusiasts, to explore the potential benefits of electric cars and whether there is a way around the practical difficulties for these to be powered with wind and other renewables. The government is keen to be seen as a world leader in so-called electromobility, with the twin aims of cutting carbon dioxide emissions from transport and providing a lifeline for its ailing car industry.
But, as it admits, electric cars only bring an indisputable environmental benefit if they are charged purely from renewable sources of energy. Furthermore, should the day ever come when that was possible on a grand scale -- which would require that all electricity feeding into the grid came from renewables -- there may be no advantage in doing so in the form of reduced greenhouse gas emissions if the green power that is taken from the grid is replaced with fossil fuel generation (box).
Despite the doubts about the practicalities and environmental benefits of running cars on green power, the government sees great potential in the concept. "Renewable energies and electric cars are a dream team for mobility without oil," declares the national energy agency. Germany is promoting "electromobility" in its Integrated Energy and Climate Program and is now encouraging technological research and market incentives for electric vehicles and plug-in hybrid cars. Hybrids run on conventional fuel for long trips and on electricity in towns. The government's aim is for one million plug-in hybrid and fully electric cars on German roads by 2020, rising to five million by 2030.
Whether cars are fuelled with clean or dirty power is not yet a primary issue for politicians. The government is giving high priority to electric cars because of the potential for reducing CO2 emissions in the transport sector. Compared with petrol or diesel, it claims that electricity from Germany's current power supply already offers a fuel with lower CO2 emissions. Energy companies are not making green power for cars a priority.
While experts debate whether electric cars in Germany really do emit fewer greenhouse gases than fossil fuel cars (box previous page), several of Europe's electricity giants are seizing the chance to expand the market for their product.
E.ON has teamed up with Volkswagen to provide electric cars with easy access to the power grid, while similar projects are under way between RWE and Daimler. Sweden's Vattenfall and BMW have their own project, Dutch utility Essent plans trials in the Netherlands starting next year, and Finnish energy company Fortum has an electric car experiment in Stockholm and is launching a similar undertaking in Finland. Japan, too, is aggressively testing electric cars.
"The development certainly won't fail for lack of electricity," Ralf Bischof of Germany's wind energy association says of the German effort. By one calculation, if ten million electric cars -- or just under a quarter of Germany's current fleet of some 45 million -- were to drive 15,000 kilometres on German roads a year, that would consume 30 TWh of electricity. "This is just 20% of the 150 TWh of wind generated power that the industry targets for 2020," says Bischof.
The government's target of one million electric cars by 2020 would need just 3 TWh a year. Conversion losses in charging the battery and sending energy to the wheels may push up that requirement according to other studies. E.ON reports that about 5% of Germany's total electricity would be required to power about 11 million electric cars.
German energy companies expect the wind power industry to grow separately -- but parallel -- to the electric car market. For the energy majors, creating a bridge between the two sectors hinges on an assumption that there will be long periods with excess wind power that needs to be stored. Yet even when wind power is meeting as much as 50% of system load, only about 10% of the wind generation would occur at times when it would be surplus to requirements. That is not likely to be enough to make paying for storage worthwhile.
Where storing wind energy could make sense is in the small but lucrative balancing and reserve power markets. One school of thought has electric cars storing surplus wind power in periods of low demand, when prices are low, and feeding some of that power back into the grid when demand for electricity, and thus its price, is high. In that scenario, the economics of storing wind power might make sense, although simply turning the wind turbine off when there is no demand for its electricity is likely to be the cheaper option.
For a genuine surplus of green electricity to occur requires wind to be replacing fossil fuel generation across an entire system and not just locally. That is a long way from being achieved. Denmark is a world leader, but gets just 20% of its electricity from wind power. Higher penetration levels first require major investment in transmission capacity in all countries.
Using electric cars to store wind means they are effectively providing the balancing power needed by grid operators to keep supply matched to demand, but with the car owners paying for the service. RWE and Daimler in Berlin are jointly studying how energy stored in car batteries could automatically be fed back into the grid when needed. According to the Wuppertal Institute for Climate, Environment and Energy, one million cars could theoretically hold a capacity of 3 GW of power.
How storing wind power in car batteries could provide balancing power in practice has yet to be demonstrated. The probability of electric cars being available, with full batteries, exactly where and when the system needs them, could be low. Car battery storage would also need to compete on the balancing market with more flexible storage systems, such as pumped water and, if they become available, compressed air stations. All forms of storage, however, are currently more expensive for meeting peaks in demand or to fill in gaps in production than conventional power system reserves.
For now, Germany is trying to determine whether dedicated storage capacity will be needed as wind energy contributes more to electricity supplies. Wind currently supplies about 7% of German demand. A study by Deutsche Energieagentur (DENA), the German energy agency, is looking into power network requirements for renewable energies, especially wind power, after 2015. Its research will be completed by the end of next year. DENA will also compare the entire life cycle of manufacture, fuel use and disposal of conventional and electric cars.
The German government is already pencilling electric cars into blueprints for the future grid. It says integration of intelligent electric storage systems "and especially development and testing of electromobility," will play important roles in six planned projects in a EUR 140 million research program titled "E-Energy -- Information and communication based energy systems of the future." How wind figures in the plans remains to be seen.