Industry gears up for a lighter footprint
Cost, convenience and technology are restricting the commercial appeal of environmentally friendly models, writes Philip Lord
THE car is about to undergo revolutionary change, the most significant since the world’s first car, built by Karl Benz, coughed into life in 1886. In 2007, the car’s contribution to detrimental global CO levels is well- documented. Fortunately, there are many new innovative paths car companies are walking down to reduce the car’s carbon footprint.
While it appears plausible that we will all drive zero- emissions electric cars in some form or another in 15 years, at the moment problems with cost, convenience and battery technology are restricting their mass- market appeal. Bridging the gap between existing cars and the electric cars are cleaner, more efficient developments based on present technology.
For example, Volkswagen has recently taken two well- known performance technologies and successfully married them not only for driving pleasure but also for the environment. The Volkswagen Golf’s Twincharger TSI engine is both turbocharged and supercharged — which has been done before in high- performance applications, but never in a run- of- the- mill road car engine that displaces only 1.4 litres.
The turbocharger and supercharger are both air pumps — pumping in air into the cylinders, squeezing in every last bit of air and, in conjunction with a sophisticated, high- pressure direct fuel injection system, makes the engine highly efficient. A turbocharger, driven by the engine’s exhaust gases, does not work well at low revs when exhaust gas output is low, while the opposite is true of a supercharger, which is driven from the engine via a belt drive. The clever part of the TSI engine is that its supercharger and turbocharger work in series, making the most of their respective strengths and efficiency. Depending on engine load, the supercharger is disengaged by a magnetic clutch by 2400 rpm, by which time the turbocharger has built- up pressure and can do its best air- pumping work up to the engine’s 7000rpm redline.
The beauty of this technology is that it allows you to put your foot down without leaving a huge carbon footprint. For a small 1400cc petrol four- cylinder engine, the TSI’s outputs are startling: 125kW and 240Nm of torque between 1750 and 4500rpm. Claimed fuel consumption is 7.7L/ 100km, 0- 100km is achieved in 7.9 sec and CO output is 183g per km. Volkswagen claims that performance compares with a 2.3- litre engine, but fuel consumption and emissions are 20 percent less. Volkswagen’s own naturally aspirated Golf 2.0- litre is slower, thirstier and emits more CO2.
The modern turbo- diesel engine is known for its excellent torque and fuel- burning efficiency with corresponding low fuel consumption and CO2 emissions, but it’s also wellknown for emitting relatively high levels of pollutants such as nitrogen oxides and diesel particulates, or soot.
Mercedes- Benz may have the solution to this diesel dilemma in the form of its BlueTec technology, introduced last year and most recently shown at the 2007 Geneva Show as the Vision C220 BlueTec.
The C220 BlueTec engine has all the features of current diesels technology, such as four valves per cylinder, third- generation common- rail direct injection, turbocharging with a variable nozzle turbine and exhaust gas recirculation. And just like many current EU4 emissions- compliant turbo- diesels, this BlueTec engine features an oxidising catalytic converter, which reduces emissions of carbon monoxide and unburned hydrocarbons, as well as a particulate filter. However, what is special about this engine is a nitrogen oxides storage catalytic converter, which when combined with an additional ‘ Selective Catalytic Reduction’ catalytic converter, slashes nitrogen oxides emissions.
The Vision C 220 BlueTec has a power output of 125kW and a peak torque figure of 400Nm but uses only 5.5L/ 100km, and Mercedes claims the technology is so clean that it will soon be ready to comply with tough EU6 emission regulations, which are not enforced in Europe until 2015.
A persuasive solution for CO reduction is the hybrid, as most employ an electric motor for the short trips with the added convenience of an on- board battery charging system for the longer trips that battery reserves alone will not sustain. The most recent development comes from General Motors, who created and subsequently abandoned its EV- 1 electric car trial 11 years ago. GM has made a cautious return to electric cars with its Chevrolet Volt concept. GM has signalled it is serious about putting a version of Volt into production — its first electric- motor motivation, internal combustion engine- assisted hybrid.
The Volt uses GM’s E- Flex platform, a chassis specifically designed to accommodate electric vehicle components. While GM calls it an electric vehicle, it is actually a series hybrid — it has a turbocharged, 1.0- litre threecylinder engine that acts as a generator charging the Lithium Ion battery pack. A 120kW electric motor drives the Volt and the battery is charged by plugging it in to any standard domestic outlet and is fully charged in about 6 hours.
The Volt will travel 60km on battery power but if further travel is needed and there is no time to hook up to mains power, the Volt has a range of more than 1000km when its engine automatically starts and supplies charge to the batteries. If driven for 35,000km annually, and charged on mains power every night, GM claims that the Volt will reduce CO emissions over a car that achieves 10L/ 100km by 4.4 metric tonnes.
GM believes that flexibility is needed for cars like Volt, as the dictates of a particular market require. Accordingly, GM has designed the Volt platform to cater for ethanol, hydrogen fuel cell or pure battery power.
The only thing that is holding up GM’s first production run is battery design. Once it finds a satisfactory Li- Ion battery pack — and can obtain enough volume to supply the production lines — then it appears Volt will be set for mass production.
While GM’s hybrid is an improvement of technology already available, no one has produced a significant zero- emission car — the closest perhaps was the ill- fated GM EV- 1 of 1996. Electric cars typically have a short range before the battery runs out of power. It presents no problems for short- haul use but for the touring ability required by most car owners, the headache has been how to get battery- power electric cars to drive without long recharge times.
The US company Tesla Motors may be the first to go close to solving this problem when its battery- powered $ US98,000 sports car goes on sale later this year. The Tesla Roadster is powered by a lithium- ion battery pack that Tesla Motors claims is its biggest innovation, allowing the Roadster a range of 300km and a supercar- like 0- 100km/ h acceleration time of 4 seconds. It also claims the battery pack will last up to 160,000km and is recyclable. The Roadster relies on mains power ( and to a small degree, regenerative braking, where the car’s brakes feed electricity back into the battery) and Tesla claims after a 160km drive the battery back will replenish after only two hours of charging.
The Tesla Roadster may be this year’s most significant automotive technology breakthrough. While Tesla claims it has conducted Roadster durability tests with no major issues, the global automotive industry will be watching very closely to see if the Tesla experiment works.
Twincharger: Volkswagen has married two well- known performance technologies