A 'natural' solution for transportation

Feb 03, 2012 By Jared Sagoff
A 'natural' solution for transportation
Researchers at Argonne have begun to investigate adding one more contender to the list of possible energy sources for light-duty cars and trucks: compressed natural gas (CNG). Credit: Mercedes Benz.

As the United States transitions away from a primarily petroleum-based transportation industry, a number of different alternative fuel sources—ethanol, biodiesel, electricity and hydrogen—have each shown their own promise. Hoping to expand the pool even further, researchers at the U.S. Department of Energy's Argonne National Laboratory have begun to investigate adding one more contender to the list of possible energy sources for light-duty cars and trucks: compressed natural gas (CNG).

Compressed natural gas is composed primarily of methane, which when compressed occupies less than one percent of the volume it occupies at standard pressure. CNG is typically stored in cylindrical tanks that would be carried onboard the vehicles it fuels.

Because the domestic production of natural gas has increased dramatically over the past ten years, making a large number of the cars and light trucks currently on the road CNG-compatible would help to improve U.S. energy security. "As a country, we don't lack for natural gas deposits," said Argonne mechanical engineer Thomas Wallner. "There are fewer obvious challenges with direct supply than with most other fuels."

Natural gas currently comes primarily from deep underground rock structures, including shale. Recent improvements with hydraulic fracturing, or "fracking," a controversial process that some critics claim can hurt the environment, have made it economical for natural gas companies to extract a greater supply of natural gas from unconventional sources.

Like gasoline, both the production and combustion of CNG release into the atmosphere. To be able to make an accurate comparison to gasoline, scientists and engineers will need to look at each stage of the fuel's production and use, said Argonne environmental scientist Andrew Burnham.

Unlike gasoline, however, CNG markets are relatively insulated from geopolitical shocks, said Wallner. "The price of CNG has been and will probably continue to be both cheaper and more stable over the long term than gasoline," he said.

CNG currently costs the equivalent of about $2 per gallon, roughly half that of current gasoline prices, according to Wallner.

In order for CNG to take hold, many more stations will need to offer it as an option, and the infrastructure for delivering and distributing the fuel around the country will have to be built up. There are currently fewer than 1,000 publically available CNG refueling stations in the United States, in comparison to nearly 200,000 gas stations.

Argonne already has the capability to help automotive industry leaders test and analyze CNG vehicles. In particular, Argonne's Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model gives experts the ability to examine the greenhouse gas emissions of various fuels from "well-to-wheels," involving each stage of production, distribution and combustion. "We have years of expertise working with industry to develop alternative-fuel vehicles as well as the tools necessary for the public to understand the impact of these vehicles on the environment," said Argonne mechanical engineer Michael Duoba.

Although CNG vehicles emit fewer greenhouse gases than conventional automobiles as fuel is combusted, "upstream" challenges in production and distribution of CNG—particularly methane leakage -- make it somewhat less attractive when it comes to preventing climate change. "There are a lot of points in the life-cycle of the fuel where we still need better data," Burnham said. "There are technological opportunities for us to capture the leaked and reduce greenhouse gas impacts."

For heavy-duty applications, like city buses, CNG might have the potential to cut down emissions of particulate matter and nitrogen oxides, helping municipalities to meet more stringent EPA standards enacted in the past few years, according to Burnham.

In Wallner's view, CNG vehicles—like plug-ins and diesel-powered automobiles—will serve the transportation needs of some, not all. "It's important to see each of these technologies as a part of the solution but not the entire solution," he said. "The more we invest in their development, the closer we'll come to a portfolio that makes sense both economically and environmentally."

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antialias_physorg
4 / 5 (3) Feb 03, 2012
"There are fewer obvious challenges with direct supply than with most other fuels."

Well, the one challenge with such a non-renewable source is: CO2.
Eikka
2.3 / 5 (4) Feb 03, 2012
Well, the one challenge with such a non-renewable source is: CO2.


Methane happens to be the easiest biofuel to produce. You toss biomatter and water in a bucket, introduce methanogenic bacteria, and they convert 99% of the stuff they can eat into methane in the absence of oxygen.

CNG is basically methane, so once the fossil supplies run out, we can simply make more.

And CNG engines can easily run on propane or other gaseous fuels. The lack of infrastructure is not a problem as long as the local fuel station has a propane tank, or has standard propane cylinders that they send for refills. You can bridge the gap with propane until there's enough CNG vehicles around to warrant a dedicated tank and pump.
Eikka
2 / 5 (3) Feb 03, 2012
One pound of propane equals roughly 0.17 gallons of gasoline, so a standard 20 pound propane cylinder contains the equivalent of 3.4 gallons of fuel.

If your car does 40 miles to the gallon, that's 137 miles you can drive, and when you run out you just pull up and exchange your cylinder to a full one.

If the engine in your car was actually a SOFC (a fuel cell), it would turn over 50% of the fuel into electricity. Assuming 250 Wh per mile and 50% overall efficiency, you'd go about 230 miles on a 20 pound cylinder.

So, it's not a problem at all if you can't find a CNG pump. Most fuel stations have propane refills, and if you keep visiting the same station for a fill-up, it becomes more economical for them to get a CNG pump for you.
ryggesogn2
1 / 5 (6) Feb 03, 2012
The US and 50 state govts are going to have to shift from a gasoline use tax to something else or the states and feds will oppose alternate fueled vehicles.
The only reasonable alternate will be some type of toll system. GPS and cellular technologies will enable methods for documenting and recording the toll charges. This would also support traffic management changing toll rates as a function of the time of day.
Shootist
1.8 / 5 (5) Feb 03, 2012
ethanol, biodiesel, electricity and hydrogen


ethanol: 1/2 the btu/lbs of petroleum. costs more in energy to make and distribute than is recovered in its burning

Electricity is made from coal. Coal is good. Coal is great. Coal will be our savior. But it is more efficient to turn the coal into synthetic gasoline and burn it as gas, rather than burning coal into electricity, then storing that electricity in batteries.

Biodiesel is good as long as it is made from waste products. But it too, costs more in energy to produce than it releases in combustion.

Hydrogen is not an energy source it is a form of energy storage. There ARE NO HYDROGEN MINES. It also costs more energy to produce than it releases in combustion.

We need Sources of Energy not Energy Sinks.
Eikka
4.5 / 5 (2) Feb 03, 2012
Electricity is made from coal. Coal is good. Coal is great. Coal will be our savior. But it is more efficient to turn the coal into synthetic gasoline and burn it as gas, rather than burning coal into electricity, then storing that electricity in batteries.


Not really. The process of turning coal into gasoline requires a lot of water, and it runs at 50% efficiency at best because you also need to produce hydrogen on the side. Gasoline, after all, is a hydrocarbon.

50% left after production, 25% left after the engine, leaves you with just 12% of what you started with.

Electric cars on the other hand, 37% at the turbine, 75% at the end of the grid and through the battery, leaves you with 28% of your energy remaining.

Clearly the electric car is better than synthetic gasoline from coal.
kochevnik
1 / 5 (2) Feb 03, 2012
GPS and cellular technologies will enable methods for documenting and recording the toll charges. This would also support traffic management changing toll rates as a function of the time of day.
The world outgrew your tenancy society in the 15th century. Fail.
GrandM4x
1 / 5 (1) Feb 03, 2012
It also costs more energy to produce than it releases in combustion.


Of course it does. That's thermodynamic second law. Currently water electrolysis is from 50 to 70 efficient. If electricity is made from renewable energies, then it is not a big problem. It may be a nice way to store energy. Unfortunately, hydrogen needs to be stored at very high pressure (up to 700 bar) so it is quite unpractical. Also, the lack of infrastructure is a showstopper. There is no silver bullet.

antialias_physorg
5 / 5 (3) Feb 03, 2012
Methane happens to be the easiest biofuel to produce. You toss biomatter and water in a bucket, introduce methanogenic bacteria, and they convert 99% of the stuff they can eat into methane in the absence of oxygen.

The article talks about gas foound in the ground ('shale', 'deposits', ...) and released via fracking. Doesn't sound like environmentally friendly/sustainable solutions are part of the idea.
GrandM4x
3 / 5 (2) Feb 03, 2012
The article talks about gas foound in the ground ('shale', 'deposits', ...) and released via fracking. Doesn't sound like environmentally friendly/sustainable solutions are part of the idea.


It can also be made from organic waste. Overall, CNG is certainly the most interesting carbon-based fuel and the cleanest. I doubt the electric car industry will grow as fast as we'd want. Maybe CNG can participate.
antialias_physorg
5 / 5 (4) Feb 03, 2012
It can also be made from organic waste.

Certainly. I just found the way the article was written misleading. The 'natural' part in the headline seems bogus (on the other hand, 'natural' was in quotes)

Unrelated to the article: Burning stuff in a carnot cycle for mobility just seems so last millennium.
ryggesogn2
1 / 5 (3) Feb 03, 2012
Oil is not natural?
Burning stuff in a carnot cycle for mobility just seems so last millennium.

What is more efficient, robust and ready for prime time?
GrandM4x
1 / 5 (1) Feb 03, 2012
Oil is not natural?
Burning stuff in a carnot cycle for mobility just seems so last millennium.

What is more efficient, robust and ready for prime time?


Batteries are just too bulky and expensive for transportation. We will have to wait a few years before we can ditch our ICE. Plus they are becoming much more efficient. Direct injection just started. Now people play with EGR, valve timing, injection pressure, multi-shot injection, injection timing, throttle-by-wire, boost pressure. We are starting to optimize all these parameters at the same time.
kochevnik
5 / 5 (1) Feb 03, 2012
What is more efficient, robust and ready for prime time?
Somalia and Yemen, according to you
canuckit
not rated yet Feb 03, 2012
"More than 10 years ago, Fiat introduced the 'Natural Power' line, through which it established a leadership position in vehicles powered by CNG Compressed Natural Gas."

http://green.auto...icles-t/
Eikka
not rated yet Feb 03, 2012
What is more efficient, robust and ready for prime time?


Solid Oxide Fuel Cells.

They're not yet reliably miniaturized to vehicle use, but if you want to make electricity out of methane, they're pretty much the best you can get.

The only thing that can compete in efficiency are complex multi-stage combined cycle powerplants that basically run jet engines to turn generators and then steam turbines with the exhaust heat of the jet engines.
Callippo
1 / 5 (1) Feb 04, 2012
The IAP Short Course (7 days) on Cold Fusion and Lattice Assisted Nuclear Reactions at Massachusetts Institute of Technology MIT has meticulously developed the salient point that skeptics of cold fusion were wrong, and that scientific theories do exist for understanding the difficult to achieve reactions. http://coldfusion...it-again This solution will indeed make all "natural" solutions pretty uncompetitive. Wouldn't be cheaper and more considerate environmentally to invest into cold fusion research directly, rather than into methods of harvesting of methane from rocks? These methods aren't cheap and environmentally friendly at all. The methane is expelled from rock with hot steam and detergents, which contaminate the sources of underground water. http://news.natio...n-water/
ryggesogn2
not rated yet Feb 04, 2012
"More than 10 years ago, Fiat introduced the 'Natural Power' line, through which it established a leadership position in vehicles powered by CNG Compressed Natural Gas."

http://green.auto...icles-t/

CNG vehicles are readily available, except that refueling stations are not ubiquitous.
Automobiles are part of a system and all aspects of that system need to be considered.
antialias_physorg
not rated yet Feb 04, 2012
What is more efficient, robust and ready for prime time

That really depends on what kind of countries and with what kind of infrastructure present you're looking at.
In most of Europe electric vehicles are ready for prime time because distances are shorter and the ability to put up a recharge-station infrastructure in minimal time is there.

In the US...well...oil is probably the thing that will have to be used for the foreseeable future.
ryggesogn2
not rated yet Feb 04, 2012
I have heard tourists to the USA say that they plan to drive around the US visiting the most popular tourist spots.
The first day they plan to visit the Statue of Liberty, the second day Chicago, the third day the Grand Canyon, ...
If anyone plans to drive across the country, or even a 2-3 day drive, if one has to map out fuel stop because of a specialty fueled vehicle, most people would use a vehicle the can be fueled at any fuel station along the route.
I like the idea of driving a car onto a freight train and letting it do the driving while I hang out in a passenger car. But there are rules against that.
Eikka
not rated yet Feb 04, 2012
In most of Europe electric vehicles are ready for prime time because distances are shorter and the ability to put up a recharge-station infrastructure in minimal time is there.

In the US...well...oil is probably the thing that will have to be used for the foreseeable future.


Technically, Europe is bigger than the US. Go from Portugal to Lapland, and that's something like 5000 miles for you. The difference is that there isn't a culture of driving from coast to coast just to meet your grandparents, because they're likely to live in the same state as you.
ryggesogn2
not rated yet Feb 05, 2012
The difference is that there isn't a culture of driving from coast to coast just to meet your grandparents, because they're likely to live in the same state as you.

One can travel across all 50 states and still speak the same language and use the same money and not need a passport.
Driving 5-6 days across the country is not as common as flying. 5-6 days vs 6-7 hours flying?