Natural gas waits for its moment

Paul Stenquist

asdCars and trucks powered by natural gas make up

a significant portion of the vehicle fleet in many parts

of the world. Iran has more than two million natural gas

vehicles on the road. As of 2009, Argentina had more

5 than 1.8 million in operation and almost 2,000 natural

gas filling stations. Brazil was not far behind. Italy and

Germany have substantial natural gas vehicle fleets.

Is America next?

asdWith natural gas in plentiful supply at bargain

10 prices in the United States, issues that have limited its

use in cars are being rethought, and its market share

could increase, perhaps substantially.

asdAccording to Energy Department Price

Information from July, natural gas offers economic

15 advantages over gasoline and diesel fuels. If a

gasoline-engine vehicle can take you 40 miles on

one gallon, the same vehicle running on compressed

natural gas can do it for about $1.50 less at today’s

prices. To that savings add lower maintenance costs.

20A study of New York City cabs running on natural

gas found that oil changes need not be as frequent

because of the clean burn of the fuel, and exhaust-

system parts last longer because natural gas is less

corrosive than other fuels.

25asdToday, those economic benefits are nullified by

the initial cost of a natural gas vehicle — 20 to 30

percent more than a comparable gasoline-engine

vehicle. But were production to increase significantly,

economies of scale would bring prices down. In an

30 interview by phone, Jon Coleman, fleet sustainability

manager at the Ford Motor Company, said that given

sufficient volume, the selling price of natural gas

vehicles could be comparable to that of conventional

vehicles.

35asdIt may be years before the economic benefits

of natural gas vehicles can be realized, but the

environmental benefits appear to be immediate.

According to the Energy Department’s website,

natural gas vehicles have smaller carbon footprints than

40 gasoline or diesel automobiles, even when taking into

account the natural gas production process, which

releases carbon-rich methane into the atmosphere.

asdThe United States government appears to favor

natural gas as a motor vehicle fuel. To promote the

45 production of vehicles with fewer carbon emissions, it

has allowed automakers to count certain vehicle types

more than once when calculating their Corporate

Average Fuel Economy, under regulations mandating

a fleet average of 54.5 miles per gallon by 2025.

50 Plug-in hybrids and natural gas vehicles can be

counted 1.6 times under the CAFE standards, and

electric vehicles can be counted twice.

asdAdapting natural gas as a vehicle fuel introduces

engineering challenges. While the fuel burns clean, it

55 is less energy dense than gasoline, so if it is burned

in an engine designed to run on conventional fuel,

performance and efficiency are degraded.

asdBut since natural gas has an octane rating of 130,

compared with 93 for the best gasoline, an engine

60 designed for it can run with very high cylinder pressure,

which would cause a regular gasoline engine to knock

from premature ignition. More cylinder pressure yields

more power, and thus the energy-density advantage

of gasoline can be nullified.[...]

65dUntil the pressurized fuel tanks of natural gas

vehicles can be easily and quickly refueled, the fleet

cannot grow substantially. The number of commercial

refueling stations for compressed natural gas has been

increasing at a rate of 16 percent yearly, the Energy

70 Department says. And, while the total is still small,

advances in refueling equipment should increase

the rate of expansion. Much of the infrastructure is

already in place: America has millions of miles of

natural gas pipeline. Connecting that network to

75 refueling equipment is not difficult.

asdAlthough commercial refueling stations will be

necessary to support a substantial fleet of natural gas

vehicles, home refueling may be the magic bullet that

makes the vehicles practical. Electric vehicles depend

80 largely on home charging and most have less than half

the range of a fully fueled natural gas vehicle. Some

compressed natural gas home refueling products are

available, but they can cost as much as $5,000.

asdSeeking to change that, the Energy Department

85 has awarded grants to a number of companies in an

effort to develop affordable home-refueling equipment.

[...]

Available at: <https://www.nytimes.com/2013/10/30/au-tomobiles/natural-gas-waits-for-its-moment.html? :pagewantted=allemodule=SserchemabReward=relbias%3Ar%2C%7B%222%22%3A%22RI%3A18%22%7D%>

Retrieved on: Sept 3^rd, 2014. Adapted.

A célula H4 do trecho de planilha Excel 2010 (português), apresentado abaixo, foi preen...