Green threshold

Electric vehicles might reduce local pollution but unless the energy used to charge them is from sustainable and renewable energy sources rather than burning fossil fuels, then the benefits may not outweigh their negative consequences, globally speaking. Now, Canadian researchers have calculated a threshold - about 600 tonnes per gigawatthour- above which switching to so-called eco products will take some of the sheen off the green. They suggest that for electrification to lower emissions, whether cars, high-speed trains or other systems, the energy and emissions costs of building and maintain the systems has to be lower than the costs of simply burning fossil fuels as we have done for almost two centuries to power our industries and vehicles.