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.
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