The world has a lot of natural gas and not nearly enough crude oil. To address the imbalance, some companies have tried to convert the gas into a liquid that can substitute for refined oil products like gasoline and diesel, but the idea has not taken off in this country. It may be simpler to convert vehicles instead and have them burn natural gas instead of gasoline or diesel.
Jean ParsonsTanks made of carbon fiber composite materials, incorporating nano-materials to make them lighter and stronger.This logic has become stronger as the price of oil has risen on the global market and the price of American natural gas has declined. Lately oil has been trading at around $100 a barrel, but the same amount of energy can be bought for about $15 as natural gas when that fuel is trading in the range of $2.50 per million B.T.U.’s, as it has recently. (An average barrel is 5.8 million B.T.U.’s.)
Few car drivers will buy a natural gas vehicle, however, because it is hard to find places to fill it. One of the most successful natural gas cars, from a technical standpoint, was the Ford Crown Victoria, which had a trunk so large that even with natural gas tanks squeezed in, there was still space for two bags of golf clubs. Ford started selling it in 1996, but it gave it up as unprofitable in 2004. Converting vehicles to natural gas is expensive.
The fleet market, though, is much stronger, with buses, trash trucks and medium- and heavy-duty trucks using the fuel.
Now, 3M is planning to introduce a new product that it says will make the conversions easier and allow the natural gas to be squeezed into a smaller space. Natural gas on vehicles is usually stored at a pressure of 3,500 pounds, and the tank is the most expensive single component of the conversion, which can run $8,000 or more over all. But by using a new material, 3M says it can allow storage at higher pressures in a lighter tank (which takes less energy to haul around), at a lower cost.
The company uses carbon composites, which are carbon fibers woven into a cloth-like mat, interspersed with an epoxy that holds them together. That technology is fairly standard.
The innovation is that 3M is putting nanoparticles into the epoxy. These sit between the fibers and increase their stiffness and the strength of the composite over all. Carbon fibers have always had very good tensile strength, meaning that if something pulls on either end, they cannot be pulled apart. But if they are creased, the layers can come apart and the structure is weakened. By adding stiffness, the nanoparticles reduce that damage.
The company also lines the inside of the tank with an impermeable plastic. Its longer-term idea is that the tank technology will have other uses. “We think we’ve got a winning solution for hydrogen, which is much higher pressure,’’ said Rick Maveus, the company’s global business manager for advanced composites. The hydrogen would be used in fuel cells.
3M has an agreement with Chesapeake Energy, a natural gas company that converts vehicles and builds fueling stations, that calls for Chesapeake to pay $10 million for design and certification work. (The new product cannot be sold until it is approved by the Environmental Protection Agency, which 3M says will take most of the rest of this year.)
It is 3M’s hope that better onboard storage will improve market acceptance of natural gas trucks and buses. “If you can address the issue of range and capacity, we would place our bets on compressed natural gas,” Mr. Maveus said.
