Chapter 7 CNG

Still going with the PR that I wrote back in the fall semester. This chapter got short shrift because I realized I spent way too much time on Ethanol and Biodiesel, and this was next.

“It is change, continuing change, inevitable change, that is the dominant factor in society today. No sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be.”

- Isaac Asimov




Compressed natural gas (CNG) is an odorless, colorless, gas that is composed of methane (CH4) and has been pressurized for use in transportation. For a long time, natural gas was considered a by-product of oil drilling and would be flared at the well, a practice still used in some countries. Around the mid-1950s, natural gas came into its own as a commodity and has become a greater component of the United States’ energy market ever since. The US has large quantities of natural gas on domestic lands and is therefore in a position to benefit from its use as an alternative fuel. The following will be a discussion of the general advantages and disadvantages of CNG, its emissions, its ability to support national security, sustainability factors, its economic impact, and future potential.
General Advantages
One of the best advantages of CNG is that the US has an abundant supply of natural gas located within its defined borders. Current reserve estimates total around 591.5 trillion cubic feet (Tcf) of natural gas as dry gas, wet gases, and gas solids. One gasoline gallon equivalent (gge) is 126.67 cf of gas meaning there are over 4.7 trillion gallons of fuel available just from domestic sources . Not all of this gas will be used for transportation, however, as many newer electricity generation facilities use natural gas as well. But it does show that as a component of a general alternative fuel policy, it could provide years of transportation power.
Another interesting development that is very tantalizing is the Phill™ home CNG fueling system. The Phill device is twice the size of a breadbox and mounts to the wall of the consumer’s home, is connected to the house electrical and natural gas supply, and is used to refuel a CNG vehicle. This has to be one of the best developments in alternative fuel distribution, one of the major stumbling blocks to widespread usage. The machine eliminates the hurdle of availability by placing the refueling mechanism in the consumer’s home, a solution that people are much more likely to use than driving to the other side of town.
The machine isn’t perfect though; it has a very slow fueling rate of .42 gge per hour, necessitating overnight refills. Also, it adds an extra cost to owning and operating a CNG vehicle which already suffers from high incremental costs (electrical use is negligible, about $18 per year). It suffers from availability as well, being offered only in six states and three cities, as well as France. The concept is not diminished by these facts, however. That an alternative fuel takes advantage of existing networks of infrastructure to offer refueling in the home reminds one of the 1950s visions of the future.
Natural gas is also a mature industry. It thus benefits from a vast network of pipelines that enable easy and inexpensive transportation of the fuel to all parts of the nation. It is perhaps because of this that CNG has one of the widest available fueling networks, second only to propane. There are over 1,300 CNG fueling stations nationwide in 46 states according to the EPA and it is possible to plan a trip across the country using a natural gas vehicle (NGV), a feat not possible with most other alternative fuels.
Also, prices at the pump are generally much lower in gge compared to gasoline. The Alternative Fuels Price Report for September, 2005, prices CNG $0.65 lower than gasoline and $0.69 lower than diesel. Finally, CNG can replace both gasoline in light-duty vehicles and diesel in heavy-duty vehicles making it a more versatile fuel than ethanol or biodiesel and thus capable of displacing more petroleum.
General Disadvantages
There are disadvantages to using CNG as well, the most prominent being availability NGVs. Currently, there are only three models available to consumers in the US market, two pickups from GM, either dedicated or bi-fuel (CNG only or CNG and gasoline, respectively), and one sedan, the dedicated Honda Civic. These three vehicles didn’t even make the DOE’s www.fueleconomy.gov list of 2006 model year vehicles, an oversight that seems odd considering the source. Given the meager offerings of CNG vehicles, it is not surprising to find that there are only 130,000 vehicles currently driving the roads, only 4 hundredths of one percent of all vehicles.
Even if more vehicles were available, it is questionable how willing people would be to purchase them because incremental costs associated with the vehicles range from $2,500 to $6,000. Perusing Honda’s website garners the following information:
• The gasoline model of the Honda Civic starts at $14,560,
• The Hybrid Civic model starts at $21,850, and
• The Civic NG model starts at $21,760.
This shows the Civic NG being $7,200 more than the same model which uses gasoline, higher than EPA figures. Given this information, it is questionable how many compact car buyers would be willing to pay an $7,000 premium to purchase the natural gas option. It also seems likely that those people willing to pay the premium might opt for the hybrid Civic, which offers guaranteed ability to fuel your car at 180,000 stations nationwide with substantial increases in mileage and reductions in emissions.
Another disadvantage CNG suffers is infrastructure costs. The average cost to upgrade a fueling station is around $300,000 due to the need for thick walled storage tanks and pressurization equipment. Costs are lower for fueling systems that pump at lower speeds but those are only good for fleet vehicles that can take the time to refuel overnight. But this too increases costs for refueling. If a bus fleet uses slow-fill CNG fueling apparatuses, it needs to build more fueling lanes and purchase more machines to fuel the fleet in time for the next day’s business. This can increase costs over the use of fast-fill machines, which are really the only option for retail gas stations. Such high costs are likely to make retail station owners reluctant to upgrade, inhibiting the availability of CNG as an alternative fuel.
Grade for Advantage and Disadvantages: B-
Emissions
Life-cycle emission of CNG can be modeled using the GREET system, making for equal comparison with ethanol and a few other alternative fuels. Chapter 4 presents the findings for emissions of CNG in a comprehensive manner; therefore, this section will be a quick review. Please, use table 4.2 as a reference.
Compressed natural gas is known as the cleanest burning fuel for use in automobiles. Using the GREET model, CNG has less than 50 percent the emissions for all types of pollutants measured, save methane which shows 3.5 times the emissions level. As CNG is composed of 98 percent methane, it is not unusual that emissions of this gas would be higher considering efficiencies of internal combustion engines. Low efficiencies mean more unburned gases escape in the exhaust cycle. In this case, the unburned portion would be mostly methane.
Breaking down the fuel by type of emission, there is an 82.5 percent reduction in carbon dioxide and an 80 percent reduction in other green house gases (mostly hydrocarbons). This shows a large reduction in emission factors that contribute to global warming, making CNG a valuable fuel in this fight. There is also a 41 percent reduction in nitrous oxide and a 92 percent reduction in nitrogen oxides, both of which contribute to smog and ozone formation as well as respiratory problems.
Carbon monoxide is decreased by 54 percent and particulate matter is decreased by 90 percent. These figures show excellent potential for CNG use in EPA non-attainment areas and also for use in diesel engines (think transit) because of major reductions in “black smoke” bellowing from heavy-duty trucks. Finally, there is a 90 percent reduction in volatile organic compounds and a 95 percent reduction in sulfur oxides, both of which contribute to smog and health problems.
Given the low emissions inherent in the use of CNG and its relative availability, it is puzzling that the fuel hasn’t been promoted or used more often. With increased availability of machines like the Phill, it is likely that more consumers will begin to use CNG, which can greatly reduce pollution in urban areas.
Grade for Emissions: A-
National Security
CNG poses problems for national security. It is true that the US has large reserves of natural gas but those reserves only constitute 3 percent of world reserves, a small figure in the scheme of things. Also, the country’s demand for natural gas is greater than its ability to supply it. Already, the US is importing natural gas from Canada and Mexico at the rate of 4.2 Bcf per year and another 652 Mcf per year in liquid form from countries like Egypt, Algeria, and Trinidad. These countries are currently favorable to the US and will most likely remain that way. If demand starts to outstrip their ability to supply, however, the US may be importing another precious commodity from the Middle East, which holds around 40 percent of world reserves.
While CNG offers the ability to replace both gasoline and diesel fuel, US reserves would only last about 27.5 years at current consumption rates if all automotive transport fuels were changed to CNG tomorrow. This would give the nation time to invent and discover new ways of propelling our vehicles but it still show that it is a finite resource, one which would eventually lead to the same problems observed today. Of course, the entire US fleet won’t be converted to CNG tomorrow and won’t ever be. Also, only about one one-thousandth of consumption is attributable to transportation, meaning domestic production would have to increase dramatically to make a serious dent in petroleum consumption.
There is also the problem of availability. While 591 Tcf exist under the lands of the US, only about one eighth of that is technologically accessible. Advances in technology are certain but not necessarily to the extent that projected consumption demands will be met. This only heightens the likelihood of increased importation of natural gas, thus decreasing national security. Regardless, this fuel has the ability to displace a large volume of imported petroleum for a long period of time and its use should be promoted as a component of an overall alternative fuel policy because of this.
Grade for National Security: C
Sustainability
Unfortunately, CNG is not a sustainable fuel. It is a product of the same forces that created petroleum, except the source material was lower in the earth’s crust, which caused it to vaporize. Therefore, it is a finite resource that can, and perhaps will, be depleted in the distant future. Peak oil theorists suggest that natural gas production will also peak some 20-30 years after petroleum production peaks. If you agree with the early peak models that will be around 2030 to 2040, while more conservative models push it back to between 2050 and 2100. Either way, at some point, given current and projected consumption, natural gas will cease to be an option for transportation whereas a fuel like ethanol or biodiesel can be produced in perpetuity.
Grade for Sustainability: C-
Economic Impact
As stated in a previous section, natural gas is a mature industry having been around for over 50 years. The possibility of this fuel creating many new jobs is small, but it does currently employ many people. The Monthly Labor Review journal estimates a decrease of 29 percent in the crude oil and natural gas industry over course of this decade. Field services to oil and gas are expected to rise 7 percent and pipeline services are also expected to decline over the same period. In fact, oil and natural gas industries have seen, and are expected to see, some of the largest and most rapid declines in US industry employment over the current decade.
Industry profits are expected to rise, however, mostly due to rising prices for the commodity. While this will make some people wealthier, it will bite into the budget of most American consumers, making them less able to afford other purchases. Overall, because the natural gas industry is well established it is unlikely it will provide a boom or even a small increase in new jobs or increased economic prosperity.
Grade for Economic Impact: C
Future Potential
What is the future potential of CNG? It is still quite promising. There are not likely to be any major advances in technology as may be seen with ethanol or biodiesel but advances are likely that will make available greater reserves for consumption. The fuel’s ability to replace both major sources of automotive fuel is quite promising and its very low emissions mean it is an excellent prospect as a transition fuel until cleaner and more sustainable resources are developed. It is still hindered by being a finite resource and being proportionately scarce in the US, making it a short-term solution to the nation’s petroleum dilemma.
Grade for Future Potential: B-