Don’t get us wrong. We are not against EVs. But when so many people today just simply equate a EV with "zero emissions," as Nissan does with the Leaf in its mass marketing campaign, it is important to be reminded of the simple fact: a EV’s green impact depends on how clean the electricity it uses is. A EV has a potential to be emissions-free, and that potential cannot be fully realized unless we have emissions-free ways of generating and transmitting electricity.
When a EV feeds mainly on "dirty" electricity, like that in China where about 80% of electricity comes from burning coal, it provides no clear environmental gains over many traditional, gasoline-powered cars. To make electricity clean is far more urgent as well as difficult than simply selling EVs to the public, and there is no assurance that the latter will help the former.
Here are the numbers: The Leaf, which is to be released later this year in the US and next year in China, has a battery capacity of 24 kW·h and a nominal range of 160 km. That means, ideally, it consumes an amount of electricity of 15 kW·h covering 100 km. Adding the power losses in energy transmissions including battery charging, this requires power plants to generate about 18 kW·h of electricity . In the US, where about 44% of electricity comes from coal, on average, 0.61 kg of CO2 is produced to generate 1 kW·h of electricity in 2008, according to the Department of Energy; in China, the number is at least 1 kg CO2 per kW·h. So the Leaf will cause 18 kg of CO2 emissions running 100 km in today’s China.
Compare this to a traditional, gasoline-powered vehicle, say, a new 1.6 L Toyota Corolla with automatic transmission, one of the best-selling cars in China. According to official data, it consumes 7.2 liters of gasoline running 100 km under average driving conditions. Approximately, burning 1 liter of gasoline produces 2.4 kilos of CO2, and the Corolla thus discharges 17.3 kilos of CO2 per 100 km. Adding emissions from fuel distribution process, this number would be very close the Leaf’s 18 kilos of CO2 per 100 km (don’t forget that EV infrastructures can also cause CO2 emissions.)
The conclusion: Considering that the majority of passenger vehicles sold in China have engines of 1.6 liter or smaller, a Leaf used in today’s China would be no greener than an average car running on Chinese roads.
On the other hand, one might want to point out, China is now a global leader in developing clean-energy technology, busying installing solar panels, erecting wind turbines,and building nuclear power stations. Its installed wind power capacity more than doubled from 2008 to 2009 (although the government acknowledges that more than 1/3 of that capacity is idling and not connected to the grid), accounting for 1/3 of the global installed wind power capacity. But even at this pace, it is estimated that it will take decades for China to reach the current US level in terms of generating clean electricity, while in today’s US a Leaf would be no greener than a Prius.
Workers are building wind farms near the western China city of Jiuquan