Car companies are going green
7 Jun 2008
Faced with rising gas prices and stringent CO2 emission standards, auto manufacturers are "going green" by introducing new car models with reduced or zero carbon footprint. There are many different technologies emerging in various stages of development. Some of the new technologies are conceptual and will never make it beyond trade shows. Some are currently in the demo or trial phase but still several years away from being production-ready. Other green car technologies are a reality and already being shipped to various places in the world. This article provides an overview of the major initiatives and issues.
Evolutionary Initiatives
Many manufacturers are pursuing an evolutionary green car approach. Incremental improvements to fuel efficiency and CO2 emissions generally include vehicle weight reduction, improved aerodynamics and tweaks to the engine design. Two popular green cars that fall into the evolutionary category are the Hybrid and Smart Car. The Hybrid retains the fossil fuel-based internal combustion engine but also includes an electrical power source. The electric motor provides highly efficient torque at low RPMs when the gas engine is inefficient providing much better fuel efficiency when driving in the city. The Smart Car provides a substantial reduction in car volume, making the vehicle much lighter.
Hybrids A hybrid is a vehicle that can run on two or more sources of energy, typically gasoline and electricity. The Toyota Prius is an example of a gas/electric hybrid, also referred to as a Hybrid Electric Vehicle (HEV). The Prius recovers energy from the braking system when the brakes are applied. Acceptance of HEVs was initially very slow due to the high price tag. Now, a decade later, more than 250,000 HEVs are manufactured per year. The Prius delivers over 40 mpg and is the most popular HEV. Honda, Ford and Chevy have marketed hybrids with various levels of success. All of the major players are now planning on producing green car hybrids. This is likely due to government imposed standards. A spokesman for GM predicted that 4 out of 5 cars sold in 2020 will be hybrids as a result of increasingly tougher emissions standards.
Although there is much hype about HEVs the environmental benefit tends to be somewhat overstated. HEVs are best suited for city driving where 10%–20% fuel can be saved, depending on driving conditions, the driver and car maintenance. On the highway fuel economy is slightly lower than traditional vehicles. Look for Toyata to continue to lead the hybrid technology in the future. The longer term goal for the Prius is to deliver fuel efficiency up to 90 mpg. This will be achieved by making the vehicle lighter by using carbon fiber and aluminum. Expect plug-in Lithium-Ion batteries within several years from most car manufacturers. Plug-ins can be charged at night when electricity demand is low. There are still battery issues to be worked out (safety, temperature, performance) before we can expect mass-production. Recently a fleet of Google Prius Hybrids were converted to plug-ins.
Micro-Hybrids An initiative similar to the HEV, but without the large battery, is called micro-hybrid. The micro-hybrid, also called “stop-start”, causes the engine to stop idling during car slow down and stop conditions. This technology saves an estimated 5% - 15% for city driving and comes with a much lower price tag than full blown hybrids. Stop-start was introduced by Peugeot-Citroën on the Citroën C3 in 2004 and will be installed on most Peugeots and Citroëns in the EU on or around 2010.
Supercapacitor Hybrids Another variation of the gas/electric design is being developed by BMW. Instead of using a stack of rechargeable batteries, BMW is investigating use of super-capacitors, making the car lighter, faster and more efficient. As with hybrids, super-capacitors are charged by energy recovered by regenerative braking. The capacitors store less power but unlike rechargeable batteries, all 100% of what is stored can be utilized. The electricity is used during standing-start acceleration where an electric motor has an advantage over the internal combustion engine. The prohibitive price of the super-capacitors has prevented other manufacturers from entertaining this solution. 20% improvement in fuel efficiency has been reported.
Smart Cars If you are looking for a 2 passenger car to commute across town, no storage space and not much power over 45 mph then the Smart Car may be the choice for you. The small body in conjunction with a diesel engine makes it possible to achieve up to 70 mpg. Diesel engines are more efficient than gasoline and inherently low in hydrocarbon and CO2 emissions. The big surprise with this small car is the results being attained on safety crash tests, performing better than much larger and heavier cars. The Smart Car, made by Mercedes-benz, has turned out to be extremely popular with the dramatic rise in fuel prices. This car isn't the answer for everyone, however. Larger individuals, and drivers seeking good acceleration, will be disappointed. A Micro Hybrid version of the Smart Fortwo is being introduced in 2008. This model will be one of the most environment friendly cars available to the general public.
Revolutionary Initiatives
Some car manufacturers are being more aggressive by researching technologies not directly linked to fossil fuel such as hydrogen and compressed air. These energy sources promise significantly reduced or zero carbon emissions. But it should be recognized that electricity is still required for these solutions. The generation of electricity requires fossil fuel, nuclear power plants or alternative energy sources such as solar, wind or hydro. Therefore the problems are shifted from the automobile to a power generator. The theory being that it is easier to control emissions at a central power generator than at the car. In most cases these (revolutionary) approaches require a new energy infrastructure, making it much less practical for mass production in the near and mid-term. Two revolutionary technologies are the hydrogen fuel cell and compressed air engine.
Hydrogen Fuel Cells In 2003 President George W. Bush announced the U.S. government’s hydrogen fuel initiative for safe and cheap hydrogen fuel cell vehicles. Unfortunately the motive to move to a hydrogen-based society had nothing to do with carbon emissions or the environment. The initiative was issued to reduce America’s dependence on foreign sources of energy. Although there are several car manufacturers that have developed concept models and some have been demonstrated and even put into limited use, there are no fuel cell cars in mass production. The technical and economic challenges for large-scale use of hydrogen fuel cells are enormous. It is ikely to be several decades before they see the consumer market if it happens at all. Alternatives such as the Plug-in Hybrid Electric Vehicle (PHEV) appear to be much more viable. Unfortunately a great deal of money has been spent developing the hydrogen fuel cell technology and has been a distraction from other potential solutions for curbing greenhouse gases. The consensus among experts is that there are more practical, cleaner and safer ways to reduce vehicle emissions. Hydrogen is considered by many to be one of the most expensive and least efficient methods of tackling greenhouse gases.
Compressed Air Cars How would you like to drive a car with zero emissions and only costs a few dollars to fill up? It may be possible in the near future with vehicles employing compressed air engines. The air compression is simply a way of storing energy similar to a rechargeable battery. Indian manufacturer Tatamotors is planning a limited production run of compressed air vehicles for use in India and a few other countries. Unfortunately, this particular car model will not meet U.S. safety standards primarily due to the construction of the vehicle. Moteur Development International (MDI), the French manufacturer of compressed air vehicles, is planning a larger vehicle for the U.S. market in 2010. The Mexican government has ordered 40,000 air powered vehicles to be used as taxis in Mexico City.
One advantage of the compressed air engine is the use of few moving parts, resulting in a light engine that is almost 100% efficient delivering power to the wheels. In contrast the traditional car’s engine only delivers about 16% of power to making the wheels turn. The rest of the energy is used to move all of the engine parts (pistons, cams), transmission, accessories or lost generating excess heat. Another advantage that compressed air has over other technologies is the environmental impact. There are no concerns regarding battery disposal compared to an electric vehicle since there are no batteries to power the car. The vehicles will remain operational longer since the engine has far fewer parts and few moving parts. The lighter weight implies that the tires will last longer, another disposal concern.
Although the compressed air solution sounds like a godsend there are some disadvantages. First of all, use of air compression to store energy is not particularly efficient. Second disadvantage is that the required air pressure is significantly higher than what is provided at a typical gas station for filling tires. Electricity is required to fill the tank and thus the carbon emissions problem is transferred from the vehicle to the electric power plant. It could take up to 4 hours for a refill at home through the electrical grid (although this could often be done during off-hours at night). Using a high pressure air pump this time could be reduced to approximately 3 minutes. It all comes down to availability of high pressure air pumps. The infrastructure is not there for mass use. Another problem is that the Air Car, like the HEV, suffers with low temperature usage. These cars likely won’t be used in cold weather climates. The final concern is the safety of driving around with compressed air tanks.
Auto manufacturers should be looking at combining air with other technologies (such as hybrids and stop-start) but nothing of this nature has come out of the laboratory yet. All in all a very interesting technology that is starting to be employed in selective niche markets.
Is there hope?
Even though there is significant progress with green car technology we still have not answered the question “Is there hope for humanity?” Some experts indicate that the earth’s population will need to cut greenhouse gases by 50% from 2005 levels by 2050 or suffer dire consequences. This while the world economies and population increase at a rate in excess of 3% per year. Introduction of green cars WILL NOT solve the climate change problem. Car emissions play a small (but significant) part in the overall problem. Every individual, business and government is responsible for self-examinatiom and elimination of all our carbon emissions.
More Information
Feel free to include this article in your eZine or circulate it with the condition that no content or hyperlinks (including those below) be changed. Minor cosmetic changes can be made without authorization. Content and/or hyperlink change requires the written permission from the author. Credit must be given to the author (Steve Auger from www.goinggreenformychildren.com).
Steve Auger
| 
Copyright 2008