The transportation sector is under siege as a major source of greenhouse gases, and it is responsible for increased dependency on imported oil, not to mention the sizable costs of such imports for most nations. The price of imported oil for the US was estimated at $700bn per annum when the price of oil was around $150 per barrel earlier in 2008. Both problems can be addressed if a large percentage of passenger cars and light duty trucks can be converted to run on electricity generated from zero-carbon sources.
With increased amounts of renewable energy coming online in many parts of the world, plug-in hybrid electric vehicles (PHEVs) could be used as an effective storage medium to absorb intermittent renewable energy when it is available. Charged vehicles can run on the stored energy when needed. As an added bonus, they can conceivably supply power back to the grid during peak demand periods, serving as cost-effective distributed generation.
According to a report in The Electricity Journal, a recent study by Pacific Northwest National Laboratory (PNNL) in the US concluded that some 73% of US light vehicles can be supplied with the existing utility infrastructure in place, provided the charging was restricted to off-peak periods. That would reduce US oil imports by 6.2 million barrels per day, roughly 52% of US oil imports.
In a similar vein, a study by the Electric Power Research Institute (EPRI) and the Natural Resources Defense Council (NRDC) reported that if 60% of light vehicles in the US were converted to PHEVs by 2050 – assumed to be feasible – then US CO2 emissions would drop by 450 million tonnes. That is equivalent to taking 82 million cars off the road. The net impact on the electric power sector is a paltry 8% increase in electricity consumption.
Such ideas are moving closer to reality by the day, driven by advances in battery technology, and the realization by automakers that their future may be closely tied to the electric power sector, and not the oil sector.
According to EPRI, the average round-trip daily US commute is less than 20 miles (32 km), and 78% are under 40 miles (64 km). This means that PHEVs with a range of 40 miles will rarely (if ever) need to rely on their gasoline engines for the great majority of drivers. That is a goal within striking distance for automakers.
The limiting factors increasingly appear to be on the utility side – for example, making sure that the vehicles are charged during off-peak hours at discounted prices, so as not to put additional stress on the grid or generation facilities. ‘Tomorrow’s car is less about the vehicle and more about the grid,’ says Dan Reichter, in charge of renewable energy policy and investment at Google Inc. Google and General Electric have formed an alliance to make the grid more ‘intelligent’, so that it can handle more intermittent renewable energy and more PHEVs.
Others are promoting more reliance on renewable energy – primarily wind – to replace the use of natural gas in electricity generation. That would make more natural gas available for use in the transportation sector, reducing demand for imported oil.
The Electricity Journal, Volume 22, Issue 1, January–February 2009, Pages 17–18.
DOI: 10.1016/j.tej.2008.12.019