Latest Articles by Ni Weidou

Fuelling the future (part one)

Weidou Ni — Wed, 27 Dec 2006 14:34:00 +0000

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.

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.

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.

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.

Fuelling the future (part two)

Weidou Ni — Wed, 27 Dec 2006 10:26:00 +0000

Clean-coal technology and improved fuel efficiency are crucial to China. In the second part of an interview with chinadialogue, Ni Weidou urges development of integrated systems with a range of benefits.

chinadialogue: In China, coal is the dominant energy source and the majority of this coal is used directly for burning. What serious environmental problems are caused by burning coal?

Weidou Ni: The distinguishing characteristics of China’s natural energy resources are abundant coal, scarce oil and a little gas, so in terms of primary energy production and consumption, coal has always held a dominant position. In 2005, China’s standard coal consumption reached 2.22 billion tonnes, standing at almost 70% of total energy consumption. In the use of this coal, 80% is directly for burning. Coal burned by coal-fired power plants accounts for over 50% of this. Over 70% of power plants on China’s electricity grid are coal-fired, while hydro, nuclear and other sources of power for electricity production account for no more than 30% of the total.

When coal burns, apart from producing a large amount of smoke and dust, it can also release the harmful substances carbon monoxide, carbon dioxide, sulphur oxide, nitrogen oxide, hydrocarbon organic matter and so forth. If there are no controls on these pollutants, they will have significant damaging effects on humans’ health and environment.

Carbon dioxide is universally acknowledged to be a greenhouse gas, and reducing CO₂ emissions has the world’s attention. China’s carbon dioxide emissions are the second highest in the world right now, and coal is the main source of this.

Another pollutant from coal, sulfur dioxide, is the main culprit causing acid rain and, at present, the sulfur dioxide produced from burning coal accounts for more than 90% of total national sulfur dioxide emissions in China, the country with the highest such emissions in the world.

chinadialogue: Which methods can effectively remove the harmful pollutants produced from coal burning?

Ni: Reduction of carbon dioxide emissions is currently based on adopting clean coal technology and increasing the efficiency of power generation. At present, the mainstream technology for increasing the efficiency of burning coal is supercritical and ultra-supercritical power generation. In simple terms, “supercritical” is using a coal-fired boiler to heat water so that it evaporates, generating steam pressure as high as the critical pressure parameter. The optimum or highly efficient super-critical parameter is the “ultra-super-critical” point.

To tackle the issue of reducing sulphur dioxide, China has already launched comprehensive efforts for sulphur removal in coal-fired power generation. Up to the end of 2005, thermal-electric sulphur-removing systems with a capacity in excess of 200 million kilowatts of power were built nationally, making up approximately 20% of the total installed capacity at thermal power plants, and forming over 2 million tonnes of sulphur-removal capability.

However, due to the short time in which a large number of sulphur-removing facilities were constructed, management of safety and supervision was not to the required standards -- leading to a quality of sulphur-removal engineering which struggles to provide a guarantee of efficacy. After construction, many of the sulphur-removing systems were unable to operate normally, efficiency was low, there was a high occurrence of breakdowns, and the desired sulphur-removal results were not attained.

We need to find a more effective method for clean use of coal. Presently, coal gasification technology is seen as the cleanest method of coal transformation. It can be considered as the foundation for the future of clean-coal technology.

chinadialogue: What is coal gasification? Can all the environmental problems caused by burning coal be completely avoided by coal gasification?

Ni: Coal gasification technology can reduce the environmental impacts from the coal-use process to the lowest levels. Coal gasification is a thermochemical process, which uses coal or petroleum coke for raw material, and oxygen and steam for the gasification medium. At a high temperature, by a partial oxidation reaction, the raw material is transformed from a solid fuel into a gaseous fuel (main components: carbon monoxide and hydrogen).

This coal gasification technique is not new technology. It has long been employed widely in chemical engineering -- in ammonia synthesis and methanol production – so it is relatively well developed. In the wake of testing and approval of the concept of an integrated gasification combined cycle (IGCC) and its commercialisation, the use of the synthesised gas gained through coal gasification becomes one kind of clean-coal power-generating technology.

The reason why it is clean is because the synthesised gas -- which is made during gasification and contains sulphur components -- can be passed through purification technology, which removes ash and the majority of the sulphur oxides. This technique of removing the sulphur prior to burning is easier and more effective than removing sulphur dioxide from the coal smoke after it has burnt. Following from this, the use of coal gasification unites power generation and chemical engineering to form a system of multi-generation.

chinadialogue: How did coal gasification come to be the core ofthe multi-generation energy system?What are the advantages of establishing this kind of a system?

Ni: This multi-generation energy system from the coal-gasification process emerged from both the perspectives of environmental pollution and of finding an improved solution to the problem of liquid-fuel shortage. To briefly explain, it uses coal-gasification technology to change coal into a synthesis gas. After purification, this synthesised gas can be used for chemical-engineering product synthesis -- for example, methanol and ether, which are both very good liquid-fuel substitutes -- and power generation.

This kind of system of combined power-generation and chemical engineering can be used in achieving the optimal use of energy flow and matter flow, and in comparison to individual production, it can reduce energy consumption, as well as being able to achieve clean-coal power generation. And where it is needed, it can also bring about reductions in carbon-dioxide emissions.

In the long run, mankind must integrate the reduction of carbon dioxide into the energy process, and the multi-generation system provides very favourable conditions for doing this. It is much easier than extracting carbon dioxide from the smoke of a coal-burning power station. To sum up, it optimally brings together the manufacturing processes of many kinds of products. And this has striking benefits for basic investment, unit cost of product, pollution discharge (sulphur, mercury, particulate matter) and so forth, compared to the separate production of these related products.

chinadialogue: Is the technology for this multi-generation system well developed? How can it be brought into widespread implementation? Where do the current obstacles lie?

Ni: The technology that constitutes the large part of the multi-generation energy system is well developed. As long as each sector in China -- coal, chemical engineering, power generation -- breaks down the sector boundaries, to join forces and work together, and to increase international partnerships, then within three to five years it would be possible to establish a large-scale, pilot multi-generation energy installation, while having a significant number in use by the year 2020.

Presently, the multi-generation energy system has already got the nation’s attention. In China’s National High-Technology Research and Development Plan (863 program) -- from the most recent round of public announcements -- multi-generation systems and pilot engineering-project research have been linked together. Evidently, China will be creating an engineering demonstration project for the multi-generation system.

These multi-generation systems have exceptional potential for raising the efficiency of energy use and reducing environmental pollution -- so it would not be a mistake for a generation of people to engage in researching this.

chinadialogue: Currently, the shortage of liquid fuel for cars is becoming more serious day by day. Could the multi-generation system be used as an energy supply for cars?

Ni: Methanol, dimethyl ether and such are produced in the multi-generation energy system, and these can serve as oil-substitute products -- so this system could alleviate the nation’s oil shortage.

For example, a mix of methanol and petrol can be adjusted to different proportions of methanol, and 100% methanol can even be used as fuel for specially manufactured cars. In comparison to petrol and other traditional liquid fuels, methanol liquid fuel possesses some remarkable, differentiating features. It comes from many raw materials, has plentiful sources, burns completely and produces clean exhaust, while dimethyl ether is a good substitute for diesel. It can be seen from the burning process that, compared to diesel, it features slightly higher efficiency, less pollution and less noise. It now only needs improvements made to the oil-burning system.

Currently, colleges and universities in China -- for instance, Shanghai Jiaotong University and Xi’an Jiaotong University -- have research under way into the use of methanol and dimethyl ether. This includes research into problems such as friction damage caused to spare parts of fuel-injection systems, precise control of fuel-injection timing and the effects of sealing performance. The results of the research already have been put into use, and Shanghai is to have 10 to15 dimethyl ether-powered public buses in pilot operation.

Home page photo by LHOON

Energy integration for China

Weidou Ni — Mon, 11 May 2009 06:26:00 +0000

Energy security and climate-change challenges mean that China must make use of diverse power sources. The key is to integrate them early on, writes Ni Weidou.

Twenty-first century China faces five major energy challenges: demand for energy is rocketing, with supplies under pressure; there is a shortage of liquid fuels; energy generation is causing severe pollution; greenhouse gases continue to be emitted; and a rapidly urbanising rural population of 800 million need a source of clean energy. These factors all threaten China’s plans for sustainable development; hence energy strategy, policy and technology need to be directed toward a solution.

Some facts will not change in the medium or long term: mining and burning coal cause major environmental and ecological damage, with coal burning to blame for 70% to 80% of all sulphur dioxide (SO2), nitrogen oxide (NOx), mercury (Hg), PM2.5-10 and carbon dioxide (CO2) emissions. However, predictions show that coal is set to play a major role in energy supply up to 2050 and beyond; it will account for 50% to 60% of energy in 2050 (as opposed to around 70% currently), with 2 billion tonnes burned annually. The proportion of coal used in electricity generation will increase, from 50% currently to over 70% by 2020. This means CO2 emissions from coal-burning power generation will account for 60% of total CO2 emissions, and the costs of capturing that carbon will be huge.

Faced with worsening energy scarcity, environmental damage and climate change, China is striving to develop renewable energy sources; in particular, large-scale wind power generation.

China has ample quantities of wind to harness: an estimated 600 million to one billion kilowatts of potential wind power on land and a further 100 million to 200 million kilowatts at sea. China plans to build 30 million kilowatts of wind power capacity by 2020 and adjustments to that plan may see that figure rise to 100 million. As wind power only works at full capacity for an average of 2,000 hours, 100 million kilowatts of wind power capacity is equivalent to a 32 million kilowatt power plant. Therefore in 2020, 100 million kilowatts of wind power capacity will account for about 2.29% of China’s total 1.4 billion kilowatts of total electricity generation. Solar thermal power will account for less than 100,000 kilowatts in trial projects, and solar photovoltaic power no more than wind power. Biomass will generate the equivalent of 300 million tonnes of coal using agricultural straw, and the same again using wood.

China’s total energy consumption is rapidly increasing; generation capacity (primarily coal-burning plants) is being installed at a rate of 60 to 80 gigawatts annually: more than three times the Three Gorges Dam every year. In such a rapid expansion the role that renewable energy can play is extremely limited; the scope for substituting fossil fuels is even less. There is no hope that renewable energy will account for any significant proportion of China’s total energy supply; therefore it cannot solve any of China’s major energy issues. We must accept the reality of coal-driven power and find a route to sustainable development of energy, the economy and the environment.

Renewable energy is by nature scattered and unpredictable. China should allow diverse energy sources, including coal, oil, natural gas, nuclear, hydropower and wind, to complement each other, rather than compete with each other. A national energy system should be an organic whole, which uses a range of energy sources to provide power to end users via a “broad energy system” that diverse energy sources feed into, with each type of energy playing to its strengths. If we regard renewable energy as primary power sources plugged into an overall system, we must identify the strengths of different types of renewable energy and use these for strategic positioning within the overall system. The use of renewable energy must take into account national and local circumstances and applications: putting the right energy sources in the right places across the country.

To this end, fossil and renewable energy sources should be combined. Co-fired power plants can burn both coal and biomass; solar thermal collectors, heat pumps and natural gas can be used jointly to supply power for buildings. Solar thermal energy can be used to boost the temperature of boilers in thermal power plants. Gas turbines and compressed air can be used to store energy generated by wind turbines. Wind power and coal-based chemical plants can be combined. These are all viable uses of renewable energy sources.

China’s wind-rich areas, such as the provinces of Xinjiang, Inner Mongolia, Gansu and Ningxia, tend to be sparsely populated. Local demand for power is low and energy-hungry population centres and industrial centres are distant. However, there are plans for 10 gigwatts of wind power generating capacity in these areas (known as the “Three Gorges of the sky”), where local power networks are weak and of low capacity. The unpredictable nature of wind power means that large-scale connection to the power grid will result in instability and the additional control mechanisms to prevent it will increase costs. Similarly, other energy sources must be in place for when wind power is not available, creating an extra cost. The grid is thus currently the major bottleneck for wind power development.

Meanwhile, China’s oil shortage and reliance on overseas supplies gives rise to a number of energy security issues. A comprehensive resolution of the shortage in liquid fuels will only come from coal-based substitutes, such as coal-based methanol or dimethyl ether. Biodiesel and ethanol from cellulose crops such as corn can only be a small part of the solution. Of course, coal itself is a scarce resource, but less scarce than others. One-eighth of mined coal could be used to produce vehicle fuel every year without causing any major disruption to the overall energy supply. The use of these coal-based substitute fuels, as well as substitutes for oil-based plastics and fibres, are driving the coal chemical industry. By 2020, China will be using 300 to 400 million tonnes of coal in the chemical industry. However, this will result in large CO2 emissions, along with large water consumption. China’s coal-rich areas tend to be very water-poor, and the extra carbon emissions do not fit with the development of a low-carbon economy and combating climate change.

Large-scale development of wind power is the current trend, but the connection to the grid is a major issue. Meanwhile the coal chemical industry will come under pressure to reduce carbon emissions. Therefore, we need to find a way to use wind power and to make the chemical industry greener.

It happens that China’s wind-rich areas are also rich in coal, and this is where development of the coal chemical industry is planned. Tens of gigawatts of wind power capacity will be installed, alongside up to ten million tonnes of coal-based methanol production capacity. This provides an opportunity to combine the two industries and make the production of methanol more environmentally friendly.

There are already grand plans for coal-to-methanol plants in the provinces of Inner Mongolia, Ningxia, Shaanxi and Gansu. But if these plans are not integrated with China's overall energy policy the plants will become major sources of CO2 and large consumers of water – and therefore incompatible with the environment and sustainable development. In the long-term, they will impact on China’s energy and environment.

Therefore it is essential to research integrated and optimised energy arrangements on a local basis, with overall planning and staged implementation from trials to commercialisation to scaling-up. Resources such as wind and coal must not integrated early on, before decisions are locked in for decades to come and different industries become cut off from each other. Locking in bad decisions will hold back a new, efficient energy system and present multiple problems for energy saving and emissions reduction.

Ni Weidou is professor of thermal engineering and 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 also heads the energy strategy and technology team at the China Council for International Cooperation on Environment and Development.

Homepage image from LHOON