Thousands of Granite Staters are driving hybrid, electric or alternative-fuel vehicles as a way to save money and protect the environment.
And new CAFE (Corporate Average Fuel Economy) standards are boosting fuel economy for gas-powered cars and light trucks.
But one unintended consequence is that the gas-tax revenues that fund the roads and bridges are decreasing, in New Hampshire and across the nation.
Now there's a growing consensus among state leaders that New Hampshire should find a way to ensure all drivers are paying their fair share.
Michael Pillsbury is deputy commissioner of the state Department of Transportation. He described the problem of highway maintenance: "It takes the same effort as it did a number of years ago, it costs more and revenues are stagnant."
In the New Hampshire Constitution, the state's gas tax is called the "road toll." The state collects 18 cents per gallon from distributors, and dealers add that cost to the price paid at the pump, Pillsbury said.
The system worked just fine for a long time, he said.
"The nice thing about a gas tax is it is a user fee," he said. "If you don't drive very much, you don't pay a tax. If you drive a lot, you pay more because you're using the roads more."
But what happens if your vehicle uses biodiesel, electricity or compressed natural gas (CNG) instead of gasoline? You still use roads and bridges; you're just not helping to pay for them.
According to the state Department of Environmental Services, there were 156 electric cars registered in New Hampshire last year. And there were about 14,000 hybrids, out of a total of 1.4 million vehicles, registered here in 2011.
A previous state law required "alternative energy" vehicles to "pre-pay road toll fees at the time of registration," an amount equal to twice the annual registration fee, Pillsbury noted. It was repealed in 2001.
The idea may get a second look.
No fee on CNG
Rep. Candace Bouchard, D-Concord, chairs the House Transportation Committee. She said the idea of capturing revenue from alternative-fuel vehicles has been discussed in Concord for years.
Her own interest in the issue was reawakened when she learned that a new CNG fueling station was being built in Pembroke. There are other CNG stations - at the state DOT, Nashua Public Works Department and the University of New Hampshire.
"And a lot of commercial fleets are now switching over to CNG," Bouchard said. However, she said, "There's no user fee on that fuel."
Bouchard has begun researching the issue for possible legislation in the upcoming session.
"I look at it as just being progressive. As we're all trying to be more fuel-efficient or looking for other fuel sources, we still have to keep our infrastructure workable," she said.
Sen. David Watters, D-Dover, said he expects to file legislation addressing the issue of hybrids and electric vehicles. He's considering proposing a surcharge on the registration fee for such vehicles.
And while he expects the owners of those vehicles may grumble, Watters noted they're still saving money on the gas tax.
He's also considering proposing that any funds raised by such a surcharge be dedicated to what's called "betterment," money that goes directly to local municipalities for their roads.
That would offset property taxes that would otherwise go to maintain those roads. "And maybe that makes it more palatable," he said.
Gasoline usage trend
In the early 2000s, the gasoline usage the road toll was based on was increasing each year. But that trend has reversed, and revenue from the road toll is projected to drop about a half-percent a year, according to Scott Bryer, road toll administrator at the Department of Safety.
In fiscal year 2005, when vehicles used 860,955,143 gallons of gas, the gas tax brought in nearly $155 million, according to figures provided by the department.
In 2009, the gallonage dropped to 815,353,404, which raised about $146.8 million in road tolls. And for 2013, that figure is projected at 801,737,916 gallons, or about $144.3 million.
Rebecca Ohler is transportation and energy program manager at the Department of Environmental Services' Air Resources Division. She said there have been ongoing discussions between the DES and the DOT about the effects of reducing petroleum use and improving vehicle efficiency.
Her division is tasked with protecting air quality, Ohler said, which includes reducing air pollutants and greenhouse gas emissions from motor vehicles.
"But in our opinion, every vehicle that's on the roadway should be paying their fair share for the support of the roadway network," she said. "Bridges that continue to stand are everybody's concern."
Some states are looking at systems that tax drivers based on how many miles they drive each year, Ohler noted. But here, she said, that would work best on a regional basis, since commuters and vacationers use roads and buy fuel across state lines.
"The solutions in theory are so simple, but in practice are very complex," she said.
"In theory, you just do a formula with the weight of the vehicle and the number of miles driven and you've got your solution. But then there are people that have privacy concerns about not wanting to have to divulge how many miles they drive in a year.
"And it would be very complex to implement because it would mean all of the states need to talk to each other."
Still, officials say the state's current dependence on a gas tax to maintain the roads isn't sustainable as more vehicles use alternative fuels or get better fuel economy.
"I think as we move closer and closer to crisis, there's going to be more impetus for people to keep the conversation going and really bring some solutions to the forefront for broader discussion," Ohler said.
Pillsbury expects some of the privacy and jurisdictional concerns will be worked out over the next decade.