Friday, July 24, 2009

Natural Gas Vehicles and Hurdles to Achieve This

This week saw movement in the national Congress on increasing the number of vehicles that run on natural gas, either CNG or LNG. This is a good thing, as natural gas burns much cleaner than does diesel or gasoline, and is much cheaper per mile driven.

The price of natural gas is low at $4 per million Btu, and is expected to remain low for many years. The reason, of course, is abundant, indeed, excessive supplies of natural gas and LNG world-wide. The reasons for the excess supplies are to a small extent the economic recession (this simply reduced demand a bit), but to a much greater extent the recent successful drilling of gas wells into gas-bearing shale formations. ExxonMobil just two weeks ago announced a big gas reservoir in the Horn River Basin in Canada. Several shale formations in the U.S. also are producing great volumes of natural gas, including the Marcellus shale in and near Pennsylvania, and the Barnett shale in Texas.

LNG plants are delivering cargoes of liquefied natural gas, and this has several implications. First, a new LNG terminal in England will provide natural gas to the country, thus reducing any impacts from shut-offs by unfriendly neighbors. Second, LNG is delivered to the west coast of Mexico just south of California, but piped into California. This gas will be essential to meeting California's power plant demand and CNG cars and other vehicles.

If California continues the trend of more CNG vehicles and fewer gasoline vehicles, (a big if as explained below), the existing gas pipelines from Texas will require upgrades to provide additional capacity.

California's regulations currently are somewhat onerous for CNG vehicle conversions, which should be revised. This should be a priority for the Air Resources Board. The ARB has a valid concern that back-yard mechanics should not be converting vehicles to CNG like they swap out a carburetor or install performance headers. Adding the proper modifications for CNG includes, at a minimum, a CNG fuel tank, throttle valve, piping, and other engine modifications. If the vehicle is to have dual-fuel capability, the control system must undergo changes.

Natural gas is the logical fuel for producing electric power and propelling vehicles. It is abundant, cheap, clean-burning, and much of it is produced in the U.S.A. One can only hope that the national Congress will pass the CNG legislation, that the legislation makes sense and is not just a big show, and that President Obama has the good sense to sign it into law.

One other thing about importing LNG, especially into the Gulf of Mexico. Re-gasification requires great quantities of heat, and that heat is derived from ocean water in some processes. The ocean water cools in the process. This is just the opposite of how power plants heat a local body of water with once-through cooling for their steam condensers. It may not be enough to notice or even to measure, but it could help cool the surface waters so that hurricanes (which require warm water to sustain their winds) decrease in strength or even disappear. Another benefit in the Gulf of Mexico might be that cold water absorbs more oxygen compared to warm water, and that could help the notorious "dead zone" in the Gulf.

The floating LNG regasification system referenced above uses a two-tier vaporizer with a closed-loop system of propane vaporizing the LNG, then ocean water is used in the second tier to warm the cold propane. The net effect is colder ocean water with high-pressure natural gas produced for moving via a pipeline to shore.

Roger E. Sowell, Esq.

1 comment:

Ellie in Belfast said...


I knew methane was historically flared off at many sites and that it was not being captured, but floating regassification using ocean heat, well - facinating!