There is nothing really new about using Compressed Natural Gas (CNG) as a vehicle fuel. It works well in internal combustion engines and it is possible to squeeze enough energy on board in a reasonable size tank at a reasonable pressure to provide gasoline or diesel equivalent range. There are modification kits available for a number of automobiles, there is at least one production automobile (Honda Civic GX) and there are a number of options for buses (Viking CNG BS-III, New Flyer C/L30LF, C/L35LF, C/L40LF, etc.) suitable for municipal fleets.
The new thing, the reason that talk about CNG is growing, is that natural gas now costs about half as much per unit energy as gasoline and has an even greater cost advantage over diesel fuel.
With new software and lean-burning regimes available, CNG powered engines have improved their fuel economy to the point where they have reached essential parity with engines powered by the sister fossil fuels of gasoline and diesel. To compare fuel cost per mile, it is not a bad approximation to compare fuel costs per BTU, (or MMBTU, or therm).
I know, there are enough different units out there to cause some confusion, but if you want to do battle with the energy suppliers, you have to learn their language. Two thumb rules worth knowing – multiply the cost of natural gas in $/MMBTU by 6 and you will find out how much an oil equivalent barrel of natural gas costs. Multiply the cost of a gallon of diesel fuel by 7 and you will find out its cost in $/MMBTU.
One of my most frequently visited web sites is Bloomberg.com: Energy Prices where you can find the market prices for a number of different fuels. There you can find daily market prices (without taxes and retail mark ups) for natural gas, gasoline and distillate fuels (heating oil and diesel fuel are essentially the same composition.) Example: today, natural gas delivered to New York City gate (a trading hub) costs $13.92, the equivalent of $83.50 per barrel when converted to oil equivalent units. Diesel fuel costs $3.92 per gallon, the equivalent of $27.50 per MMBTU. Arm yourself with this information and you can see why people in decision making positions are looking hard at CNG again.
CNG vehicles have been around for a while, have good track records for safety and cleanliness, and have a growing pool of satisfied customers. The federal government also provides some generous subsidies for both individuals and fleet purchasers. Under the Energy Policy Act of 1992, natural gas qualifies as an alternative fuel, which gives it a certain tax status by providing EPAct credits.
Throw in those incentives, a shift in the market price to significantly favor natural gas and some long term marketing efforts by coalitions that include Sierra Club, NRDC, ExxonMobil, CleanAir.org, PowerCompare.org, Natural Gas Vehicle Association and Chesapeake Energy and you may soon see a lot more of those CNG vehicles on the road.
Of course, those who know me at all know that I have difficulty producing an energy related article without bringing up nuclear power, so here is the expected plug. In recent memory, natural gas has actually been far less expensive than it is today. In 2003, for example, an MIT study about energy futures assumed that the high price case would be $4.00 per MMBTU with about a 5% annual increase.
Using that prediction, gas should cost just $5.10 per MMBTU, not $13.92. The difference is that gas is now the “go to” electricity fuel. A little more than 20% of the electricity in the US is produced by burning natural gas – the quantity of gas consumed in power plants has increased by 30% since 2000.
When we begin building and operating new nuclear power plants, which run on abundant fuel that costs just $0.50 per MMBTU (including the waste storage fee), we will free up a lot of gas and drive down its market price. That will make room for a lot of domestically powered CNG vehicles and reduce the amount of oil that we need to import. (The reason I “shouted” the word OR in the title is that every BTU of gas can only be burned once. Every bit that burns in power plants cannot be burned in vehicle engines.)
That kind of talk makes it hard for aggressive nukes like me to build coalitions with other energy suppliers who are thoroughly enjoying their current market power, but how does it sound to you?
Photo credit – DC Metro CNG bus by Rod Adams under Creative Commons. (Taken in going home traffic on June 25, 2008)