Friday, July 17, 2009

Electric Avenue

Charging Stations Electrify the West Coast


Interstate 5 or, "The 5" as it is affectionately known by locals, is the major artery of the west coast. If you want to catch a ferry to Alaska, take The 5 to Bellingham WA. If you want to go to Disneyland, take The 5 to Anaheim. If you want to go to Washington, Oregon, or California by road from one of the same, you are most likely using I-5. The 1382 mile stretch runs from Tijuana to Vancouver BC passing through San Diego, L.A., Portland and Seattle just to name a few.

Earlier, we reported that I-5 was the first freeway in the US to be solar powered. This was possible in part because The 5 is federally designated as a "Corridor of the Future". This designation is also why I could post this blog entry with my WiMAX enabled notebook from the back seat of a car in northern Oregon as it zips along on I-5.

The solar-powered, Internet-enabled 5 is about to add another futurism to its list, Electric Vehicle charging stations. When the administration's green jobs stimulus money was made available, Oregon had already been running a pilot program to build and deploy charging stations in the state, making this a "shovel ready" program for Oregon.

One of the concerns often expressed is that charging for 30 minutes while you eat lunch or grocery shop is not going to fully charge the batteries. If you could get a free gallon of gas when you bought lunch, would you say "No, thanks. I need more than a gallon to fill-up my car." Of course not. So it is not a matter of filling up.

Being able to opportunistically charge, keeps the batteries from being deep cycled and makes them last longer. If you have a PHEV, it allows for more, potentially all, of that days travels to be electrically fueled. If you pull in to a rest stop on I-5 you are not likely to be there for very long. Say you use the facilities, get a coffee, eat a sandwich, and a half hour later, you are back on the road. How much of a charge could you get during this time? That depends what you plug it into.

The new standard for EV charging connectors is the J1772, defined by the Society of Automotive Engineers (SAE). It is being driven by companies like GM (in support of the Volt) and it can currently deliver two different levels of charging.

Level 1 is standard household outlet energy level (120V 15A)
Level 2 charging will be 240V at 12 Amps up to 80 Amps.
Some batteries are capable of taking a fast charge (480V 600A) and new breakthroughs are under development. This is level 3 charging and the standard is in the works. Since it is not available now, we'll leave it out of the discussion.

When a car is propelled by gasoline, it has a miles-per-gallon rating. Similarly, when it is propelled by electricity, it has a miles-per-kWh rating. Just, as with gas mileage, how you drive has a lot to with your actual results. The Chevy Volt and the Tesla Roadster have a similar electric performance of about 3 miles per kWh.

Given this, you can easily determine how fast the vehicle can charge. Level 1 charging is 120V @ 15A. That is 1.8 kWh per hour* or 5.4 miles per hour. This rate of charge would be good for overnight, but in our 30 minute stop, this is going too add less than 3 miles of electric range to a trip, not much help.

Level 2 charging, however, doubles the voltage and more than doubles the current, let see how far this could get you during a brief rest-stop. 240V @ 80A is 19.2 kWh per hour which translates to ~58 miles per hour of charge. In 30 minutes, that is about 29 miles worth of juice. The Volt has a 40 mile electric range, so during this brief stop, the batteries can be three quarters full. In a Volt, this means that you can pull in with empty batteries and running on gas and then leave running on electricity for the next 29 miles.

Let's do an example of an Oregon roadtrip in a PHEV-40 and see if charging stations along The 5 would make any difference.

Example from Portland to Eugene is 110 miles:
In a 50MPG car, this would use 2.2 gallons of gas.
In a PHEV-40 with 50MPG when depleted, this would use 12kWh of electrons and 1.4 gallons of gas. The PHEV saved some gas. Not bad, but we can do better.
Now add a 1 hour level 2 charging break in Salem. The trip now uses 24kWh of electrons and only 0.6 gallons of gas. It is tempting to say that 110 miles on 0.6 is getting 180 MPG, but that is hype-speak it ignores the electricity used. It is a slippery slope, be sure you are acknowledging that gasoline is only part of the energy mix used. You can say that stopping at the charging station cut the PHEV's gasoline usage by more than 50 percent (from 1.4 gallons to just 0.6 gallons). If the discussion is about how to get off dependence on petroleum, this is very relevant.

The PHEV with a charging break used less than 1/3rd of the gasoline of the 50MPG car (from 2.2 gallons to 0.6 gallons). And, of course, if this comparison was against a 25MPG vehicle, it would use about 1/7th of the gasoline. Clearly, charging stations can reduce gasoline use if they are placed conveniently such that drivers can "grab a few watts" whenever they stop for other reasons.

The 5 is a vital artery of west coast travel. A network of charging stations along The 5 can reduce gasoline use, reduce petroleum dependency, and reduce CO2 emissions. It is an important step in growing the infrastructure our nation needs for the coming generation of plug-in automobiles.

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