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Fuelling the future (part one)

New technologies are emerging to replace the oil and diesel that now power most cars. In the first part of an interview with chinadialogue, Ni Weidou discusses biofuels, electricity, hydrogen, hybrids and more.

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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%.

 

© Rob Welham 

 

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.

by Vj-pdx

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.

© Rob Welham

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.

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.

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Default avatar
匿名 | Anonymous

什么时候汽车才能不烧油?

最好是汽车只烧一次油,然后利用行驶做功发电,积蓄后面行驶所需的动力,自给自足。又节约又环保,希望科学家们早点把这个东西研究出来。

When can vehicles not use petrol any more?

If vehicles get power by burning petrol at the beginning, then it produces energy while driving and provides power for itself. It is energy-saving and environmentally-friendly. I wish scientists can develop it as soon as possible.

Default avatar
匿名 | Anonymous

为什么还是煤?

地下不仅仅是光有煤,还有奔腾的滚烫的火山岩浆,为什么不把这些永不枯竭的能量利用起来呢?比洁净煤更环保。

Only coal?

Apart from coal, there is also boiling magma underground. Why don't we utilize this inexhaustible supply of energy? It will be more environmentally-friendly than Clean Coal.

Default avatar
匿名 | Anonymous

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好文章。冒昧也推荐我自己的博客:
http://wangdunwebsite.blogspot.com/
学术、文笔、趣味兼备。

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Good article!
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Default avatar
匿名 | Anonymous

科学家不是万能的

又见到一个把希望寄托在科学家身上的人,我们的媒体,太多地夸大了科学的作用,尤其是对于环境,科学更多地是在其中扮演了一个反面形象。即使是一百个科学家的作用,或许都顶不上一个政治家;即使所有的科学家都在为环境努力,都肯定抵不上我们自身良好的环境习惯的养成。
二楼的更可爱了,世界上那里有永不枯竭的能源啊。当然,不应该否认人类利用火山的可能性,对了,别忘记还有其他更强大的自然力量,海啸啊,地震啊,都应该利用上,还有流星,也被浪费了,建议科学家把陨石下降的动能转变汽车石油吧,呃。。。这个任务交给雅典娜手下的圣斗士们,也许更加合适。
Aturen

Scientists can not do all the work

Our media always overestimates the power of science. Actually most of the time science plays a negative role in environment protection. Sometimes a politician is hundred times as helpful as a scientist. Our environmentally-friendly habits are more helpful than all the efforts from all scientists.

The Comment2 seems naive. Inexhaustible supply of energy does not exist at all. Probably there is possibility that human would make use of volcano, and the other natural powers like tsunami, earthquake and meteor should be turned into energy. I suggest scientists turn the kinetic energy from the falling of the aerolite into petrol … en I think Athena’s fighters will be more suitable to do it. --- Aturen