Plug-in vehicles have the potential to create the greatest challenge for electric utilities since air conditioning was introduced in the 1950s

Today, a small fleet of specialized electric co-op demonstration vehicles, drawing on the power of both gasoline and electricity, are wheeling down rural roads. Under optimum conditions, they can travel 150 miles on each gallon of gasoline.

Sound far-fetched? The Cooperative Research Network (CRN), an arm of Arlington, VA-based National Rural Electric Cooperative Association, has been conducting a project involving these cars, called plug-in hybrid electric vehicles (PHEVs), for the past 20 months. The U.S. Department of Energy’s Idaho National Laboratory and seven electric co-ops across the country have joined the effort, with a plan for 10 cars to hit the road by the end of this year.

“Part of the program is gaining real world data on what it’s like to drive one of these vehicles day-to-day, and part of it is public outreach,” explains Alan Shedd, who logged 45,000 miles in a plug-in as a commercial-industrial marketing engineer at Jackson Electric Membership Corporation in Jefferson, GA. Shedd picked up the co-op’s PHEV, a retrofitted 2004 Toyota Prius painted two-tone green and white, from a conversion shop outside Los Angeles in February 2007.

“You can’t really drive anywhere without people asking about it,” he adds. “It’s kind of flashy—especially with ‘100+ mpg’ painted right above the gas tank.”

In its study, CRN hopes to determine how these cars will perform as part of an electric co-op fleet. Any positive attention co-ops enjoy as a result provides an unexpected bonus.

“It’s really great that electric cooperatives got involved in this technology early on,” comments Shedd. “Participating co-ops deserve a lot of credit for getting out there and making this initiative happen.”

The public exposure Shedd and others provide by displaying one of the cars at co-op meetings, fairs, and other community events also lets them explain what PHEVs actually do.

Today’s hybrid cars, which many automakers are now offering, achieve greater fuel efficiency by adding an electric motor and a 1.3-kw nickel-metal hydride battery that takes over for the gasoline engine at low speeds. The gas engine kicks on during long cruises, or when the battery gets used up. Both the gas engine and a regenerative braking system constantly recharge the battery pack.

Plug-in hybrids, though, take the idea a step further by replacing the nickel-metal hydride battery with a 9-kw lithium-ion model–a much larger version of those used in cell phones and laptops–that delivers more electric power and better fuel economy. A plug-in charging system that can be accessed above the car’s left rear bumper is then installed.

When the battery runs down to where a one-third charge remains, the PHEV starts acting like a regular hybrid, using the gasoline engine to maintain that level. But the engine and brakes don’t recharge the battery much further. Instead, a full charge requires a regular 110-volt outlet.

Before being converted to a plug-in, Shedd’s off-the-shelf hybrid averaged 45 to 50 mpg. He now gets 75 to 90 mpg driving the same routes. On in-town trips of less than 20 miles, the car can average between 120 and 150 mpg.

That means far fewer trips to the gas station, as long as Shedd can plug his car in at the end of the day.

“When plugged in, a PHEV can recharge in four hours,” says Ed Torrero, CRN executive director. “Doing so consumes around 4 kilowatt-hours, or about 40 cents, of electricity. It’s cheaper to fully recharge the battery this way than charging it with the gasoline engine.”

Charging can also be done at night, when demand for electricity is low and, in some cases, rates are lowered to reflect this. A PHEV can run on the equivalent of $1 per gallon for gas—a price not seen in this country since February 1999.

While pocketbook advantages to drivers are obvious, plug-ins also offer the promise of reduced reliance on imported oil and lower greenhouse gas emissions. Combined, electricity generation and transportation account for close to three-quarters of U.S. greenhouse gas emissions, blamed as a principal contributor to climate change.

Even in a scenario where few changes are made to the nation’s current electric generation mix—with coal continuing to provide about one-half of all power produced—widespread adoption of PHEVs could reduce carbon dioxide emissions by as much as 500 million metric tons a year by 2050, according to a recent study by the Palo Alto, CA-based Electric Power Research Institute, a non-profit research consortium for electric utilities, and the National Resources Defense Council in New York City. That’s equal to permanently taking more than one-third of cars off the nation’s roads.

At the moment, plug-in hybrid electric vehicle development remains hampered by costs and still-evolving battery technology. Nickel-metal hydride batteries, for their part, are plagued by low energy density–the charge held relative to size.

On the other hand, lithium-ion batteries, such as those being deployed by CRN, are not yet proven. However, a report by the California Air Resources Board found them “making impressive technical progress worldwide,” especially in regards to longevity and safety.

Another technical hurdle involves electric utilities’ ability to handle a surge of electric-driven cars. If PHEVs are charged during times of low electricity demand, the current power grid could “fuel” as many as 180 million without the need for new generation, according to the U.S. Department of Energy Pacific Northwest National Laboratory in Richland, WA. But a rapid and more widespread adoption of the technology could severely strain distribution systems, such as those owned and maintained by your local electric co-op.

“Plug-ins have the potential to create the greatest end-use product, and greatest challenge, for electric utilities since air conditioning was introduced in the 1950s,” explains Torrero. “Air conditioning load grew much faster than expected and caught a lot of utilities unprepared. This research project is contributing to an early understanding of the technology so we can avoid any similar unintended consequences.”

When driving his PHEV, Shedd often fields questions along these lines. A popular concern is: if everyone on my block drives a plug-in hybrid, and comes home from work and plugs in at the same time, won’t we have brownouts?

“In my opinion, it’s a non-issue,” insists Shedd. “In recharging, the car draws less energy than a hair dryer. And we don’t have brownouts in the morning when everyone is getting ready for work, drying their hair, and making coffee.”

Jackson EMC recently retired its PHEV when the odometer reached 103,000 miles, and Shedd has since moved on to work as a southern regional manager with the National Rural Electric Cooperative Association. But wanting to continue his participation with CRN, Shedd “put his money where his mouth is” and bought the car from the co-op.

“I’m a huge fan of the technology—it works very well,” Shedd concludes. “This car and I, we go way back.”

Scott Gates writes on technology and energy efficiency for NRECA.