chinadialogue: In recent years, car ownership in China has been on the rise, exacerbating oil shortages and continuously pushing up the price of oil — much to the concern of the people of China. Do cars need to run on oil?
Weidou Ni: Currently in China, the domestic capacity for oil production is around 180 million tonnes. However, last year demand for oil stood at approximately 310 million tonnes, so about 130 million tonnes had to be brought in from abroad. And China’s need for oil is still relentlessly increasing, leading to a higher and higher dependency on oil imports. This not only means the spending of a considerable amount of foreign currency reserves, but also could pose a threat to energy security in China if the situation in the supplying countries of the middle east and Africa becomes unstable.
The supply shortages of liquid fuel for automobiles (mainly petrol – gasoline — and diesel oil) is going to be the bottleneck in China’s modernisation, especially with the rapid growth of the car industry and car ownership in recent years. In 2005, China produced 5.7 million cars, lagging behind only the United States and Japan to be the world’s third-largest automobile producer. From 2004 to 2005, there was an increase in car ownership of 20% and, over the last few years, the amount of vehicle fuel consumed also has increased very quickly, by approximately 12%.
The level of production is low in the national oil reserves, and liquid fuel for automobiles has to be supplied under safe circumstances. So, we should consider a question: is it essential for all cars to use petrol or diesel for fuel? Practice dictates that we use petrol and diesel to power cars, but in the event of an oil shortage, then we should look for another path.
chinadialogue: Which chemical compounds could replace petrol and diesel?
Ni: At the moment, the main substitutes for petrol and diesel to have undergone extensive research are methanol, dimethyl ether and bioethanol. Methanol (CH3OH), a petrol substitute, has a very high octane rating (or octane number). The higher this rating, the greater the “anti-knock” of the methanol (thereby reducing engine knock). Thus, when methanol is used in a petrol vehicle, this can increase the level of compression in the air cylinder, which in turn increases the heat efficiency of the engine.
Methanol petrol substitutes can be made with up to 1.6 parts methanol to 1 part petrol. Of course, there are also a number of problems with using methanol for fuel. For example, metal corrosion, expansion of rubber components, difficulty igniting the engine in the cold, exhaust fumes (such as formaldehyde), and so on. However, with a few years’ hard work, an appropriate solution can be found to all these problems. With a low methanol-petrol mix (10%), only a small number of modifications need to be made to the original engine; for a high methanol content (85%) or for using pure methanol, redesign of the engine is necessary.
That said, Chinese research units working in this field have already designed and successfully tested pure-methanol cars. There is still a large amount of scientific research and development work to be carried out in this field, and the experience accumulated during the applied use of methanol will lead to continuous improvements.
Diesel substitute dimethyl ether (CH3OCH3) has a very high cetane value, and the higher this value, the better the combustibility. In an engine, dimethyl ether combusts completely; therefore, the exhaust is notably superior to that of a conventional diesel engine. Emissions of nitrogen oxide can be reduced by over 50% compared to those of a conventional diesel engine; the engine noise is also lowered and there is no black smoke in the exhaust.
However, dimethyl ether is a gas in constant temperatures and it is only under high pressure, like 5.1 pascal, that it liquidises; therefore, it is necessary to pressurise the fuel lines system of the engine. In addition, with only 1:30 parts dimethyl ether to diesel, the friction damage caused to spare parts of the fuel-injector system and the precise control of the fuel-injection timing all have new problems which need solving.
Another possible oil substitute is bioethanol, but it is critical that this energy source does not compete with cereals and other subsistence agricultural outputs for land and water, even if a unit area has a high output rate. Biodiesel utilises the oil from oil-containing plants, animal fat and waste foodstuffs as the raw material for the liquid fuel that is manufactured. From a technological perspective, it is — in principle — ready to be introduced. The great task facing experts in agricultural energy will be how — through genetic engineering and molecular biology — to cultivate drought-resistant, alkali-resistant and high-yield varieties of energy crops on a large scale.
chinadialogue: Several years ago, “hydrogen-energy economics” was widely touted, climaxing in 2000 with the test run of China’s first-ever hydrogen fuel-cell vehicle. So how is the fuel-cell car developing now? Is it on its way to commercialisation?
Ni: I don’t really agree with the wording “hydrogen-energy economics”, and in recent years the speculation over hydrogen has been somewhat excessive. A lot of people don’t really understand what hydrogen-energy economics is all about. One statement which completely misleads people is that hydrogen energy can transform “from water to water” — this is to say that, after electrolysis, water turns to hydrogen; then, after burning, the hydrogen turns back to water and, therefore, it has zero emissions.
Solid hydrogen is just an energy source, like electricity. It can only be obtained from other non-renewable energy sources. Electrolysis consumes a large amount of electricity. Currently, getting 1 kilograms (kg) of hydrogen gas requires at least 9 kg of pure water and 45 to 50 kilowatt-hours of electricity — and this electricity comes mainly from fossil fuels.
Although there has been a great deal of investment into hydrogen fuel cells, there are still many problems which have not been solved, even in the United States or Japan. For example, the price of fuel-cell cars, the storage of hydrogen gas, the infrastructure for hydrogen supply, transportation and so forth. It is vital to have positive development of basic research into fuel-cell cars, but as to how long it actually will take for true commercialisation? I would say 15 to 20 years, at the very least.
chinadialogue: So do you think there is an alternative source of power for cars which is superior to hydrogen fuel cells?
Ni: Comparatively speaking, I am more in favour of electric cars. This is because electricity is already in widespread use and, moreover, it is extremely efficient. A good example here is hybrid cars. One main feature of a car engine is to recharge the battery, and when necessary to also help drive enabling the optimum engine performance thus reducing energy consumption.
“Plug-in” cars have been developed overseas. These cars, powered by storage batteries, can reach speeds in the range of 50 to 60 kilometres (km) per hour, and the storage battery can very easily use the electricity supply for recharging. Normally, the distances travelled in a city to and from work, or to run errands, are short — so you do not need to use liquid fuel. It is only when you want to travel a long distance in one day that you finally start up the engine, thus allowing the amount of fuel consumed by the engine to be reduced considerably.
Pure electric cars (lithium ion) have recently travelled 300km after a single charging. Urban public transport has set an example by using super-capacity zinc-air batteries, and other electricity-propelled means of transport are rapidly developing. At the moment, the main problem for electric cars is in the storage battery. If there is a breakthrough on this aspect of storage batteries in the future, the big question will be whether hydrogen fuel cells can maintain their status in terms of car power.
Looking at hydrogen fuel cells as car power’s highest goal is misguided. The course of 100 years of technological development testifies to this. Electricity is the best energy source. Many types of fossil fuels, renewables and nuclear power can all produce electricity; moreover, electric energy has already established a basic spread over the whole planet, as well as covering the national network of China. To re-build a hydrogen network is absolutely unrealistic and, furthermore, is not needed.
chinadialogue: What is the current situation regarding the development of substitute fuels in China? Has this development led to difficulties?
Ni: In general, supplying a new kind of fuel for use in cars is never going to be plain sailing. It is expected that problems will occur. But, because of this, we need our technicians to work twice as hard. Through working from theory to practice, back to theory and then back to practice again, China’s own path become clear.
The use of ethanol fuel was an innovation of China’s – linked to its domestic situation — and marks a turning point in shaping the special nature of the nation’s car industry. This approach is not often used abroad, or has only just begun (with Volvo and Mitsubishi). Similarly, if we begin with emphasising research and practice, China can advance, innovatively and with great strides, on its own path.
Next: The question of coal
Weidou Ni is a professor of thermal engineering, and was formerly vice president at Tsinghua University. He is a member of the Chinese Academy of Engineering and vice chairman of the Beijing Association for Science and Technology. Ni is also a leader of the energy strategy and technology team at the China Council for International Cooperation on Environment and Devleopment.