Natural gas fuelled cars for the country environmentally friendly

September 14, 2010
Energy monitor of a hybrid vehicle

If you are looking for an environmentally friendly automobile, think about getting a hybrid car or one running on natural-gas. In terms of CO2 emissions both perform significantly better than gasoline or diesel fuelled vehicles. On behalf of the Swiss Federal Office for the Environment (FOEN), Empa has conducted an investigation into the CO2 emissions of hybrid cars. When compared to natural gas fuelled vehicles, hybrids do better during inner-city driving, whereas on the motorway natural gas has the upper hand.

Hybrid cars and those fuelled by produce significantly less carbon dioxide (CO2) than equivalent vehicles running on gasoline. In the course of a study undertaken on behalf of the Swiss Federal Office for the Environment (FOEN), the results of which were recently published, Empa has investigated the CO2 emission behavior of current . A comparison with gasoline and natural gas fuelled vehicles concludes that hybrid vehicles are the cleanest during inner-city driving whilst natural gas fuelled cars do best on the motorway. When driven in rural areas, both types do equally well. Under mixed conditions (that is real, everyday driving) vehicles based on both concepts offer reductions of up to 25 per cent in CO2 emissions compared to conventional gasoline fuelled automobiles. Hybrid drive systems and natural gas engines therefore represent an important technical measure for reducing CO2 emissions which can be put to use immediately, as do vehicles powered by such as biogas and ethanol derived from waste matter.

Practically-based comparisons in the laboratory

During the study, Empa engineer Robert Alvarez and colleagues, compared the of three different hybrid cars. The fuel usage characteristics were measured on a dynamometer, both for the standard driving cycle as well as for “real world” driving profiles, which better simulate everyday driving under inner city, rural and motorway conditions. In addition, the researchers measured the amount of energy returned to the storage batteries during regenerative braking (known as recuperation) and the current supplied by the batteries to deliver extra torque to the engine when necessary.

CO2 emissions from hybrid cars, natural gas fuelled cars and gasoline fuelled cars (3 vehicles in each category). To make the comparison more representative, the CO2 emissions are given per kWh of power delivered during the driving profile.

The comparison with conventional gasoline engined cars showed that hybrids achieve up to twice the efficiency in city driving, which naturally has a very positive effect on their fuel consumption and CO2 emission levels. The repeated strong acceleration and braking phases combined with the modest speeds characteristic of urban “stop-and-go” driving particularly favor hybrid drive systems. Full hybrids, which can use purely electrical propulsion for short distances, achieved even better values under these conditions than mild hybrids, which do not have this ability, or the luxury-class hybrid evaluated in the test. Because of their weight, vehicles belonging to the latter category are generally equipped with a large internal combustion engine and a comparatively smaller electric motor.

On the other hand, during rural driving hybrids show little savings in terms of fuel consumption or CO2 emissions and on the motorway none at all compared to gasoline engined vehicles. Because of the power required to propel the vehicle at country-road or motorway speeds the electric motor is hardly able to offer any additional support to the internal combustion engine. In summary, hybrid vehicles are therefore ideal as city runabouts.

Natural gas fuelled vehicles are another alternative

In terms of CO2 emission reduction, natural gas fuelled vehicles represent another alternative, with the further advantage of significant additional economy. Technically, they are practically identical to gasoline fuelled vehicles, but they generate less carbon dioxide because natural gas contains less carbon than gasoline. Their level of CO2 emission lies about 20 to 25 per cent below that of an equivalent vehicle fuelled with petrol, but above that of a full hybrid (see figure). During rural driving conditions natural gas fuelled cars and hybrids are equally “clean”, and on the motorway natural gas fuelled vehicles actually emit less CO2 than hybrid cars. Taken over all three driving profiles, the total levels of natural gas powered automobiles are therefore quite comparable to those of hybrid vehicles, and when rural and motorway driving predominate then they are in fact better.

Explore further: AT&T to put 8,000 natural-gas vehicles on road

More information: "Effect of hybrid system battery performance on determining CO2 emissions of hybrid electric vehicles in real-world conditions", R. Alvarez, P. Schlienger, M. Weilenmann, Energy Policy (2010), published online on 3rd August 2010, DOI:10.1016/j.enpol.2010.07.008

Related Stories

AT&T to put 8,000 natural-gas vehicles on road

March 11, 2009

(AP) -- AT&T Inc. said Wednesday it will spend up to $350 million over five years to buy more than 8,000 Ford Motor Co. vans and trucks, then convert them to run on compressed natural gas.

Different energy mixes will fuel plug-in hybrid cars

August 18, 2010

Few drivers know exactly which well in which country their gasoline comes from, and from an environmental standpoint, it may not matter. Burning petroleum from the United States, Canada, Russia or Iran would each release ...

Reducing CO2 through technology and smart growth

February 11, 2009

A Georgia Tech City and Regional Planning study on climate change, published February 10, 2009 online by Environmental Science and Technology, shows that "smart growth" combined with the use of hybrid vehicle technology could ...

Study: Are plug-ins the next wave of hybrid vehicles?

September 25, 2007

Is America ready for rechargeable cars? Teams of researchers at the University of Michigan and Pacific Northwest National Laboratory will explore this question and others with $2 million from the U.S. Department of Energy's ...

UC Davis Will Study Users of New Plug-in Hybrid Cars

October 30, 2007

The latest green car goes under the UC Davis microscope today: a hybrid sedan modified to recharge from a standard 110-volt electric outlet. It can travel as far as 20 miles on batteries before drinking a drop of gasoline, ...

Recommended for you

The world needs to rethink the value of water

November 23, 2017

Research led by Oxford University highlights the accelerating pressure on measuring, monitoring and managing water locally and globally. A new four-part framework is proposed to value water for sustainable development to ...

'Lost' 99% of ocean microplastics to be identified with dye?

November 23, 2017

The smallest microplastics in our oceans – which go largely undetected and are potentially harmful – could be more effectively identified using an innovative and inexpensive new method, developed by researchers at the ...

Mysterious deep-Earth seismic signature explained

November 22, 2017

New research on oxygen and iron chemistry under the extreme conditions found deep inside the Earth could explain a longstanding seismic mystery called ultralow velocity zones. Published in Nature, the findings could have ...


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (2) Sep 14, 2010
If you add to the natural gas fuel an accurate penalty for the amount of CO2 separated from the raw natural gas at the production well (50 to 100% by volume), THEN it rapidly becomes a far worse fuel regarding climate change then heavy oil, oil sands, or even CTL. This site

claims that the associated CO2 which is separated out and vented is "0% to 8%" but I've seen documents from Japanese companies producing LNG in Indonesia who state that ratio is closer to 100%.

All I'm saying is that these topics are typically a lot more complex than they look like at first glance. Be sure you know where you're going before you start running.
1.5 / 5 (2) Sep 14, 2010
Natural gas is clearly best, and cleanest in other emissions besides CO2. In addition, the energy cost is currently 50 cents per gasoline gallon equivalent (gge), without taxes, compared to bulk gasoline at $1.98. Utah has lots of natgas filling stations selling at about $1.50 per gge. (

We're missing a big opportunity in natural gas as vehicle fuel. The US has 100-200 years' supply, already comprising 23% of all US energy. Oil supplies 35% of all US energy, and we're wasting $400 billion a year importing much of it.
not rated yet Sep 14, 2010
Well, electric hybrid autos fueled primarily by solar thermal generation with an auxiliary generator fueled by diesel or gasoline (oil sands eventually shale), natural gas (less efficient overall but acceptable) are clearly the way to the future. Given the existence of the liquid fuel infrastructure in place, and the potential for N America to become import-independent this way (Canada's oil sands) it looks like the right way to go. And BTW, the minute natural gas becomes significant for road fuel you'll see the price (and road taxes) rise to exactly compete with liquid petroleums.
1.5 / 5 (2) Sep 14, 2010
When compared to natural gas fuelled vehicles, hybrids do better during inner-city driving, whereas on the motorway natural gas has the upper hand.

ARE YOU KIDDING! You needed a study to tell you this? Come on folks. Now lets consider a hybrid car running on natural gas rather than gasoline... lets do a study! Common sense folks.

hybrids only get the great mileage in city driving, this is well known. Gas is better than gasoline. A gas hybrid is better than a gasoline hybride. Seriously guys, stop studying, we need real implementation on a large scale.

I don't think natural gas is the ideal solution, it has the exact same health consequences as gasoline, more cancer, shorter lifespans, birth defects, etc,etc,etc.

lengould100 ,

Hydrogen hybrid with heat recover, plug-in capacity, solar cells, and regenerative breaking is the future if they ever let it come to fruition.

No more studies are required, we have the technology for mas production now. I am serious.
3 / 5 (2) Sep 15, 2010
"Hydrogen hybrid"

And pray tell, where would you be getting that hydrogen from?
1 / 5 (1) Sep 15, 2010
If your smart enough to ask that question, you should already know that answer. NUCLEAR + Renewables buddy. Nuclear can generate hydrogen at 95% efficiency via high temperature electrolosis.

Anyone who advocates generating hydrogen via fossil fuels is either seriously ignorant, probably the result of propaganda, or just a plain old stooge for big oil.

Does this answer your question sufficient;y? Any more challenges?
2.3 / 5 (3) Sep 15, 2010
Yes, there are many more challenges. Before any system can replace the existing system it must be economically equal to or better than the existing system over the course of its entire product lifetime, and also acceptable to consumers in terms of usability and maintenance. Hybrids are too expensive right now, both in terms of initial cost and in terms of cost of ownership over time. Then there is also the infrastructure needs to consider. You have to have fueling/charging stations and logistics, mechanics who know how to work on them, spare parts distribution and logistics, etc. Any time you have two competing systems, you will add costs to both systems because of duplicated efforts and overhead too. It's not like you can just pass a law and make it happen. I surely don't want to go turn in my gasoline burning car, which is fully paid for and running well, in exchange for an expensive hybrid. Also: anything that needs batteries isn't ready for mainstream due to battery problems alone.
1 / 5 (1) Sep 15, 2010

All those challenges are address, as is the case with any successful endeavor:

Before any system can replace the existing system it must be economically equal to or better than the existing system...

-hydrogen hybrids have FAR cheaper fuel when produced from nuclear than a gasoline car.
-zero pollution
-reduction in cancer rates and, as a result, healthcare costs.
-no loss of performance is required nor usability, hydrogen actually takes less time to fuel.
-maintenance isn't a serious issue. If we took the stance of education before implementation we wouldn't have the internet... these happen in parallel. Dealer machanics will be trained long before any product is brought to market.

Hybrids are too expensive right now..

- they are a bit high in price, and ugly, right now, but this is changing rappidly.

1.5 / 5 (2) Sep 15, 2010
infrastructure needs...

Agreed, lets get on it now! Seriously, how long did it take to replace the old fueling stations with pay at pump stations (this has occured many times), how long did it take to put an ATM machine at every store? Installing charging stations would be far cheaper than any of the previous stated projects, which all require power + communication and other components while charging stations are the size of a lunch box and only require power connectors.

Any time you have two competing systems, you will add costs to both systems

-agreed, but this is just initial costs not long term. fossil needs to be fazed out. Rather than subsidizing oil and gas, we can subsidize consumer hybrid purchases.

Also: anything that needs batteries isn't ready for mainstream due to battery problems alone

-your gas car has a battery two buddy. Also, it only takes a small solar array connected directly to the battery to tripple its life.
Those were nonissues
1 / 5 (1) Sep 15, 2010

Quoting myself
your gas car has a battery two buddy. Also, it only takes a small solar array connected directly to the battery to tripple its life.

-battery manufacturers don't want you to know this. A very small influx of current while the car is sitting significantly reduces plate (anode/cathode) corrosion.
not rated yet Sep 15, 2010
My EV's get 250 and 600mpg equivalents. And they use lead batteries!! It's that reason that EV's are the future.

For instance a car run on NG gets say 50mpg. But an EV run from a cogen 50% eff NG powerplant, would go 250-300 miles on the same base NG. Plus EV's can run on nukes, or you can make your own power by wind or solar. 1kw of PV or wind, under $2k now, can charge an EV for 30-50 yrs.

H2 in an ICE or foolcell gets 1/4 the mileage for the same energy input. There is no H2 capability which is very costly and who wants a 10k psi tank in their car?

NG has the same safety problem. Unless it's design from scratch, NG in cars is dangerous at 5-10k PSI. Now for NG hybrid trucks, NG is a winner.
1 / 5 (1) Sep 15, 2010
Thanks JerryD, I'm not at all against EVs, so long as we dont produce the electricity from fossil. Once these new advance batteries come out (if they let em) Whoopi
not rated yet Sep 15, 2010
The best solution to our transportation needs I have heard of so far has been using nuclear/solar power to create steam, then using that steam to produce syn-gas and from that liquid hydrocarbon fuel (gasoline equivalent). All the carbon atoms come from biomass. Sine we are not trying to get the energy from the biomass at very low efficiency, we can use anything that grows, directly and without preprocessing.

The whole process is carbon neutral because all of the carbon was biomass sequestered CO2 from the air.

Best of all, we can keep the same infrastructure, because we are just getting the liquid fuel from a different source, not trying to replace it. Add in hybrids to make everything more efficient and you have a complete carbon neutral transportation sector.
1 / 5 (1) Sep 16, 2010
"The whole process is carbon neutral because all of the carbon was biomass sequestered CO2 from the air."
-only in theory. Carbon isn't raelly stored in plants until they die and are burried, especially considering the artifical fertizler issue. Again, burning hydrocarbons produces carcinogens which kill a lot of unknowing innocent people.
-Why not just produce hydrogen, which would inevitably be a more efficient process (you got to get the C and H for the hydrocarbon from somewhere! Why not just produce the H and forget the C)
-Infrastructure: Our infrastructure is, literally, crumbling and farly obsolete, why not just replace it? It really isn't that big of a challenge, it's smaller than the healthcare challenge in my eyes.
-The infrastructure, as I am sure you are aware, is going to be completely replaced or overhauled may times in the life of this country over the next 1000 years, just get used to it. If we took your stance, we would still be talking over telegraph lines.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.