In the most recent environmental news, we’ve heard the number “230” a lot lately. 230 miles per gallon is what General Motors is claiming their new Chevy Volt will get in the city. Sounds incredible, right? Let’s take a closer look at what’s actually behind that number and why it might not be as green as it sounds.

In an article, “The Chevy Volt: Mileage Numerology“, published in the New York Times today, it points out that the number behind this claim is relatively speculative and hard to measure accurately. The vehicle line director for the Volt, Tony Posawatz, suggests that while we’re used to measuring in miles per gallon, plug-in hybrid vehicles may be better measured by cost per mile. He says that the Volt will achieve around two cents per mile (assuming electricity costs 10 cents per kilowatt hour) versus 12 cents a mile for gas-fueled cars at $3.60 a gallon.

Chevy describes the Volt on their website :

Unlike traditional electric cars, Chevy Volt has a revolutionary propulsion system that takes you beyond the power of the battery. It will use a lithium-ion battery with a gasoline-powered, range-extending engine that drives a generator to provide electric power when you drive beyond the 40-mile battery range.

Cheaper to drive and more fuel efficient sounds extremely promising, and it can be. But in order to power the batteries, we need to put more stress and more demand on the grid. A greater demand on the grid will force utilities to provide quick electrons and how they choose to fulfill that need will be a key factor in how green electric cars truly are.

So an important question must be raised: even if electric cars are more efficient and cheaper than gas cars to drive, will we demand clean power to meet all this new stress on our grid? Or will we switch from using oil to burning coal to power the electric car revolution? While the development of batteries gets more federal funding, and models such as the Volt are due out on sales lots by the end of next year, where is the funding and the push for greater renewable energy sources? If we are changing the way we commute to be more environmentally-friendly, shouldn’t our source of energy be clean?

Therefore we need to play catch-up in the renewable energy market and allow solar, wind and other renewable technologies to become a primary source of electricity before we can truly celebrate this transition. Plug-in hybrids and electric vehicles can only be as clean as their fuel source and right now we are still using oil and burning coal in power plants to produce most of our power.

As the momentum builds for plug-in hybrids, let’s also push for a greater investment in clean energy. Before we add a large piece of our transportation to the country’s electrical system, let’s green the grid. If we can use clean energy to power efficient electric vehicles, then the Chevy Volt and the advent of the electric car will truly be, electrifying.