Featured Research

from universities, journals, and other organizations

Hybrids as city runabouts, natural gas fueled cars for the country

Date:
September 14, 2010
Source:
Swiss Federal Laboratories for Materials Science and Technology (EMPA)
Summary:
If you are looking for an environmentally friendly automobile, think about getting a hybrid car or one running on natural gas. In terms of carbon dioxide emissions both perform significantly better than gasoline or diesel fueled vehicles.

This diagram shows CO2 emissions from hybrid cars, natural gas fueled 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.
Credit: Swiss Federal Laboratories for Materials Science and Technology

Hybrid cars and those fuelled by natural gas 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 hybrid cars. 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 renewable fuels 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 fuel consumption 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.

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. 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 CO2 emission 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.


Story Source:

The above story is based on materials provided by Swiss Federal Laboratories for Materials Science and Technology (EMPA). Note: Materials may be edited for content and length.


Journal Reference:

  1. Robert Alvarez, Peter Schlienger, Martin Weilenmann. Effect of hybrid system battery performance on determining CO2 emissions of hybrid electric vehicles in real-world conditions. Energy Policy, 2010; DOI: 10.1016/j.enpol.2010.07.008

Cite This Page:

Swiss Federal Laboratories for Materials Science and Technology (EMPA). "Hybrids as city runabouts, natural gas fueled cars for the country." ScienceDaily. ScienceDaily, 14 September 2010. <www.sciencedaily.com/releases/2010/09/100914100256.htm>.
Swiss Federal Laboratories for Materials Science and Technology (EMPA). (2010, September 14). Hybrids as city runabouts, natural gas fueled cars for the country. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2010/09/100914100256.htm
Swiss Federal Laboratories for Materials Science and Technology (EMPA). "Hybrids as city runabouts, natural gas fueled cars for the country." ScienceDaily. www.sciencedaily.com/releases/2010/09/100914100256.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
China's Drone King Says the Revolution Depends on Regulators

China's Drone King Says the Revolution Depends on Regulators

Reuters - Business Video Online (July 30, 2014) Comparing his current crop of drones to early personal computers, DJI founder Frank Wang says the industry is poised for a growth surge - assuming regulators in more markets clear it for takeoff. Jon Gordon reports. Video provided by Reuters
Powered by NewsLook.com
3Doodler Bring 3-D Printing to Your Hand

3Doodler Bring 3-D Printing to Your Hand

AP (July 30, 2014) 3-D printing is a cool technology, but it's not exactly a hands-on way to make things. Enter the 3Doodler: the pen that turns you into the 3-D printer. AP technology writer Peter Svensson takes a closer look. (July 30) Video provided by AP
Powered by NewsLook.com
Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins