Helps Save Fuel, Swiss Study Finds

Science (June 22, 2010) — Automobile air conditioning systems do not run “free of charge.” In fact in the hot parts of the world they can account for up to thirty per cent of fuel consumption. Even in Switzerland, with its temperate climate, the use of air conditioning systems is responsible for about five per cent of total fuel usage, rising to around ten per cent in urban traffic, as shown by a new study undertaken by Empa on behalf of the Swiss Federal Office for the Environment (FOEN). Furthermore, two thirds of the additional fuel usage could be saved if air conditioning systems were simply turned off when the air temperature falls below 18 degrees Celsius.

Car air conditioning systems require energy to compress the cooling agent, and the greater the degree of cooling required the more energy (i.e. fuel) they use. Little known, however, is the fact that these systems also used fuel when the outside air temperature is cooler than in the vehicle. For this reason the Federal Office for the Environment (FOEN) gave Empa the task of investigating in detail the fuel consumption of six modern cars — both diesel and petrol models — with their air conditioning systems switched on and off under varying ambient temperatures and humidities.

The study, the results of which have just been published in the scientific journal “Environmental Science and Technology,” shows that the fuel consumption of the test vehicles with air conditioning systems in operation increases with rising ambient air temperature and humidity, reaching a value of some 18 per cent on a typical Swiss summer day with an air temperature of 27 degrees and relative humidity of 60 per cent. In addition, the researchers noted that the air conditioning systems in cars with automatic transmissions (which today are the most widely sold models) only turn themselves off when the external temperature drops below 5 degrees, when the cooling system could ice-up. This occurs because air conditioning systems not only cool the air before blowing it into the vehicle interior but also dry it, so as to avoid causing condensation on the front windscreen when it rains, among other reasons. This is of course perfectly sensible and important for safe driving, but only when the air humidity is high, and not all the time — as is currently the case.

Using the standard climate model defined by the Swiss Society of Engineers and Architects (SIA, Bern^*) and allowing for the measured increase in consumption (plus the use of the vehicle during the day), the average annual extra consumption of a petrol-engined car works out to 5.4 per cent. Differentiating between urban, suburban and motorway driving gives additional fuel usage values of 10, 2.8 and 1.3 per cent respectively.

It is known from physiological studies that the average driver feels comfortably warm when the air temperature around the head is 23 degrees. This means that if the outside temperature is below 18°C the car’s air conditioning system could be turned off without any loss of comfort. For the petrol-engined vehicles investigated this would represent a saving of some two-thirds of the additional fuel usage, which is after all 3.6 per cent of the total consumption. When the outside temperature is higher, it is advisable to keep the air conditioning switched on since otherwise the heat may affect the driver’s concentration and reduce safety.

With the diesel fuelled vehicles tested, the additional consumption due to the use of air conditioning, particularly for urban driving, is somewhat lower (2.7 per cent in total). The individual values for urban, suburban and motorway driving in this case are 4.5, 2.3 and 1.2 per cent respectively. The potential saving possible through switching off the air conditioning unit when the outside temperature falls below 18 degrees remains, however, two thirds of the additional consumption for the diesel vehicles tested.

If the entire Swiss automobile fleet is evaluated — that is, including vehicles without air conditioning systems as well as older models with inefficient compressor units — then a figure of 3.1 per cent of additional consumption is arrived at, assuming all air conditioning units are in use over the whole year. This drops to 1 per cent if air conditioning units are switched off when the ambient air temperature falls below 18 degrees. This simple measure could therefore result in a reduction in total fuel consumption of some two per cent across the whole country.

^* The SIA standard climate model contains hourly weather data such as temperature and relative humidity over a compete year and is used by architects to calculate insulation and heating requirements for buildings.

Sourced & published by Henry Sapiecha

India to Focus on Electric Vehicles

A number of lectures on the policies and current states of electric vehicle (EV) development in China and India were delivered at the 24th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition (EVS24), which took place in Norway from May 13 to 16, 2009.

China is planning to allot half the total transportation energy consumption to EVs and fuel cell vehicles (FCVs) that primarily use energy other than petroleum by 2020. In India, on the other hand, the diffusion of EVs has become an important issue due to its environmental problems and transportation conditions.

Gasoline cars, EVs to co-exist for some time in China

Automotive sales are growing extremely fast in China. They reached about 9.3 million units in 2008 and are likely to surpass 10 million units, the largest sales volume in the world, in 2010. The number of vehicles owned in China is currently 40 million and is forecast to reach 150 million in 2020.

C. C. Chan, president of the Electric Vehicle Association of Asia Pacific China, and Duan Ruichun, executive president of Chinese Electro-technical Society China, reported data on automotive development including EVs in China.

China is planning to reduce gasoline cars and hybrids, which are powered primarily by oil, and allot half the total energy consumption in the transportation segment to EVs and FCVs, which are powered by energies other than oil, Chan said.

As half of the existing cars will remain, China will (1) maintain the infrastructure for gasoline and other liquid fuels, (2) make its mileage regulation for gasoline cars etc, meet international standards and (3) give priority to high-efficiency direct-injection engine cars and hybrids until 2020.

Ruichun said China is conducting 863 projects concerning EV and FCV development to meet this goal. As a result of those projects, EVs and hybrids are currently running in 13 cities in China. And the Chinese government is planning to increase the number of those vehicles to more than 1,000 units within three years.

At first, EVs and FCVs will be diffused as means of public transportation. To accomplish this goal, the government will increase the subsidies for purchasers of electric buses, etc. For example, for the purchase of a hybrid, electric or fuel-cell bus with a total length of 10m or more, a subsidy of up to Rmb420,000 (about ¥5.88 million or US$61,600), 500,000 (¥7 million) or 600,000 (¥8.4 million) will be paid, respectively.

As for the purchase of a general EV, a subsidy of up to Rmb50,000 (¥700,000), 60,000 (840,000) and 250,000 (3.5 million) will be granted to the purchaser of a hybrid, EV and FCV, respectively.

Aided by those stimulative policies, China is already at a state where it can start producing core technologies for EVs and automotive platforms, Ruichun said.

“We have already achieved 2,000W/kg output density of a Li-ion secondary battery with a current capacity of 6 to 100Ah and mounted a 1,300W/kg output motor with more than 93% efficiency on a car,” he said, emphasizing the fact that EV development is making smooth progress in China.

EVs are suited for India

Meanwhile, Indian population will outnumber the world’s largest Chinese population, exceeding 1.4 billion in about 2030. The Indian automotive market has been growing at an annual rate of more than 15% as well. The market will maintain the same scale as in the preceding year even during the global recession of 2008 to 2009.

The diffusion of EVs seems to have become a pressing challenge in India.

“Considering environmental issues, we will face a serious trouble if we do not start spreading more EVs in priority to gasoline cars,” said Chetan Maini, deputy chairman and CTO of Reva Electric Company of India.

“In large cities, the degree of atmospheric pollution due to auto emission is by far worse than our safety standards,” said Shanta Chatterji, chairman and managing director of Chattelec Vehicles India Ltd of India. “And the number of deaths caused by diseases from air pollution has already outpaced that of deaths in traffic accidents.”

EVs are suited not only for environmental reasons but also for transportation conditions in India. Behind this is the fact that “long-distance driving is difficult in India because of heavy traffic congestion in urban areas,” Maini said. He revealed that 95% or more of automobiles in India are estimated to travel 80km or less per trip, with 80% traveling 25km or less.

“An EV equipped with a Li-ion secondary battery can travel about 120km per charge,” Maini said. “In other words, more than 95% of cars in India can be covered. Even when traveling 240km, the EV can travel the distance with a quick charge for about 1.5 hours. So, there will be no problem if more than 99% of cars in India are EVs.”

Moreover, there is little chance that traffic congestions will improve in India, where urban population is expected to increase about 50% in 20 years.

Nevertheless, the current hottest car in India is the low-priced gasoline car, “Nano,” which Tata Motors Ltd of India is planning to release. Reportedly, nearly 200,000 units of the Nano have already been ordered.

“The diffusion of the Nano is likely to worsen the current transportation conditions and environmental issues,” Maini said, commenting on the Nano.

The Nano can be used as the second car in urban areas or a convenient car for people in rural areas. In India, the number of cars purchased as the second car has reportedly surpassed that of first car purchases since 2005.

EVs recently started to penetrate India. The total sales of electric motorcycles and EVs were about 10,000 units in 2007 to 2008, but the sales are expected to sharply soar to about 110,000 units in 2008 to 2009. However, electric motorcycles are making up the majority of the sales.

Although there are more than 15 manufacturers of electric motorcycles in India, only few Indian manufacturers deal with EVs or hybrids. At this moment, Reva is the only EV manufacturer and Mahindra & Mahindra Ltd is the only hybrid manufacturer in India. Tata, on the other hand, is planning to market EVs in Europe as a starter.

The Indian government is currently devising policies with three pillars, “ecology,” “economy” and “social equity,” to diffuse EVs. Of these three pillars, EVs hold the key to both ecology and economy, Chatterji said.

Sourced and published by Henry Sapiecha 1st July 2009