Cement production in China is a significant emitter of carbon emissions, but technological advances and an economic slowdown could see the sector becoming a main player in scoring the country’s climate action goals

PROBLEM
China produced 2.13 billion tonnes of cement in 2018, 52% of global output, emitting 1.3 billion tonnes of carbon dioxide, equivalent to around 10% of its national emissions

SOLUTION
Change to low carbon cement production, use waste instead of coal to power the sector and reduce the oversupply of cement as the economy slows

KEY QUOTE
“It is like vegetable producers; you need a whole range [of cements] to meet all customers needs. The future construction industry will have more tailor-made and specialised applications.”

Low hanging fruit for reducing huge volumes of carbon emissions is waiting to be plucked in China. Take the cement industry. By halting overproduction of cement in a slowing economy and applying decades-old knowledge to more energy efficient and less carbon emitting production processes, the country could make a significant dent in its CO2 reduction goals. Pressure is mounting on China to act. More and more countries are pledging to release no more carbon dioxide than they produce by 2050, or earlier. To reach so-called “net zero” emissions, all heavy industry has to make significant investment in changing production processes and none more so than the cement industry. Of the 60% contribution by China’s manufacturing industry to the record 13.7 billion tonnes of CO2 emitted by the country in 2018, a quarter of global emissions, fully 1.3 billion tonnes came from cement production, around 10% of national emissions. The 2.13 billion tonnes of cement produced by China in 2018 represented 52% of global cement output in that year. Yet China has no use for such large volumes of cement. The country has been struggling for years with a serious overcapacity problem. In 2013, the government issued formal guidance including a “resolute curb on the blind expansion of production capacity”, banning production that would increase net cement capacity and ordering an end to sub-standard cements. Together these measures were supposed to stop the manufacture of 340 million tonnes of cement a year. But in May 2018, Emir Adiguzel, former World Cement Association chairman, complained China still had 895 million tonnes of cement production capacity surplus to demand, or 45% of global production overcapacity. The national industry target for 2020 is to concentrate at least 60% of production capacity with the top ten manufacturers and to close idle production capacity. Such action would reduce production capacity by 400 million tonnes and raise the utilisation rates of remaining plants to 80% from 68%. The logic is that fewer cement players will make it easier to close factories and reduce production. Demand for cement and concrete is also expected to shrink. After 30 years of annual growth averaging 10%, China’s economy is slowing. “Old growth drivers — a growing labour force, migration from rural areas to cities, high levels of investments and expanding exports — are waning or having less impact,” says The World Bank Group in a September 2019 report. And improved cement quality will lead to longer building lifetimes. In mid-2019, scientists at Baoing and Beijing universities projected Chinese cement consumption in 2030 at 1.3 billion tonnes, half of that in 2017, and cement CO2 emissions of up to 511 million tonnes, 61% down on 2018 levels.

TECHNICAL AND POLITICAL PROGRESS
Technical and political progress is also underway, as in other regions, to shrink CO2 emissions from cement manufacturing. China, on joining the Paris Agreement in 2016, pledged to peak, not reduce, carbon emissions by 2030. Since then the country has stepped up its carbon reduction ambitions. New and weighty measures on CO2 emissions abatement and climate change are expected to feature prominently in the country’s upcoming 14th Five Year Plan. The top-level policy blueprint will include economic development guidelines for 2021-2025. And the country is showing greater commitment to tackling climate change and environmental issues. Compliance with pollution measures, such as nitrogen oxide emissions levels by the cement sector, is already much better than five years ago, says Ian Riley, chief executive officer of the World Cement Association. Pressure to comply could be stepped up further when China launches a social credit system at the end of 2020 to reward and punish certain behaviours. It will apply to individuals and companies. Businesses that violate environmental regulations could end up on public blacklists. And a European-style carbon trading system encompassing cement is on the horizon.

DATA ISSUES
One issue hampering climate action in China until now has been a lack of reliable and comparable data, but this is changing. A draft standard for CO2 reporting in the cement sector is expected to be approved within the next few months, says Riley. Information can then be added to the Getting the Numbers Right database. Managed by the Global Cement and Concrete Association, the database holds CO2 and energy performance information on the global cement industry. “From looking at energy efficiency, use of alternative fuels and the overall low clinker factor in China, we know Chinese producers will be at the lower end of the scale in terms of CO2 emissions per tonne,” says Riley. China’s average clinker factor — the ratio of clinker in one tonne of cement — was roughly 0.65, compared with Europe’s higher 0.73 in 2018. But caution needs to be exercised as a low factor can also mean lower quality cement. China’s average clinker factor has increased from 0.6 in recent years partly as a result of a government-driven phase-out of low grade cement production. Properly logging CO2 emissions from Chinese cement producers is a necessary step on the road to a European-style cap and trade mechanism. Pilot CO2 emissions trading systems encompassing cement and other industries have been tested in several Chinese cities and provinces since 2012. “But ensuring the schemes deliver policy goals and rule out cheating has been problematic,” says Riley. “The pilot schemes have had little impact, but have raised awareness and got the ball rolling.” The national CO2 emissions trading system originally scheduled for 2016 never materialised. “Instead, the government decided in 2017 on a national trading system for CO2 emissions from electricity in preference to a broader scheme that might be more easily compromised,” he explains. The initiative will be launched in 2020, with cement and other industries to be included at a later stage. The exact timeline is unclear.

CAPTURING WASTE HEAT
Despite the absence of a trading system, regulations introduced in recent years have impacted CO2 emissions, says Riley. He describes China’s approach to climate issues as “scientific”. Once a technological solution is proven, it is often swiftly implemented, he says. Riley gives excess heat recovery (EHR), where waste heat in kiln exhaust gases is recovered and used mainly for electricity generation, as an example. Since the efficacy of the technology was proven around a decade ago, all newly built Chinese kilns have been equipped with waste heat recovery systems, improving energy efficiency — 15% of input energy is wasted, compared with 35% from a modern gas power station. Conch Cement, a large Chinese producer, reports the advantages of EHR in its 2018 sustainable energy report. A clinker production line with a daily output of 5000 tonnes can use captured waste heat to produce 210-240 megawatt hours of electricity a year, saving around 25,000 tonnes of coal and reducing CO2 emissions by 60,000 tonnes. Last year, Conch’s electricity generation from waste heat was 8.3 terrawatt hours, saving just short of three million tonnes of coal and reducing CO2 emissions by eight million tonnes. Older cement works still operating without state-of-the-art waste heat recovery systems will be pushed to take action after the Chinese government warned in July 2018 that favourable electricity prices enjoyed by high-energy-consuming industries, including cement, will be phased out by 2025.

INDUSTRIAL SYNERGIES
Similarly, the co-processing of industry and urban waste is not specifically aimed at reducing CO2 emissions, but nevertheless contributes to carbon mitigation. Selected wastes are fed into kilns and burnt, with the ash becoming part of the clinker material for cement. Other wastes are burned as alternatives to coal or gas to generate the high kiln temperature required for clinker production. Every 10% increase in alternative fuel use reduces CO2 emissions by roughly 3%. Different industries are working together to create circular economies where one sector’s waste becomes another’s raw material. Partnering polyvinyl chloride (PVC) production with neighbouring cement manufacture means waste carbide sludge from PVC production can replace natural limestone in cement production, reducing CO2 emissions by 40-50% compared with conventional Portland cement clinker. Use of urban waste in the cement sector is also starting. Most still goes to landfill sites or is piled up in waste mountains, but the country’s National Development and Reform Commission issued directions on waste collection and sorting in July 2018, including a call for cement and organic fertiliser companies to use waste as a resource to partly replace coal and avoid methane emissions from fermenting stored organic waste. Urban waste in China is predicted to expand by two-thirds to an annual 500 million tonnes by 2030. The country currently has about 100 co-processing projects to dispose of municipal solid wastes, sewage sludge and hazardous wastes and demonstrate best practice for a circular economy and green cities.

LOW CARBON OPTIONS
Sixty-three per cent of emissions from cement are linked to the chemical process involved in clinker production, a significant component of cement. Simply decarbonising the energy used by cement kilns and their ancillary processes will not be enough for the country to meet its climate commitments. Low carbon cements will be needed. These new products are not yet widely used, but their higher costs may start to be accepted as regulations demand lower emissions or a carbon price is applied to otherwise cheaper cement products. Examples include calcium sulfoaluminate (CSA) cements. They cost more because of expensive raw materials, but are useful for making special purpose mortars and concretes where rapid strength development is required, including in low temperature applications, and offer emissions savings of around 20% compared with conventional Portland cement clinker. And industrial-scale production trials of reactive belite-rich Portland cement (also known as high-belite cement or HBC) — offering a 10% emissions reduction in the clinkering process —are happening. HBC is widely acclaimed for building hydro power dams without thermal cracks. CSA and HBC production are running commercially at around one million tonnes each year, says Tongbo Sui, vice president of Sinoma International Engineering, a global supplier of cement manufacturing plants and technology. “These are not big volumes,” he admits. “But this is just the beginning.” Research is also well underway on limestone calcined clay cement with Chinese government support and international cooperation. The shrinking availability of traditional supplementary cementitious materials (SCMs), such as slags and fly ash to replace some of the clinker, means alternatives are needed. Kaolinite containing clays are widely available and can be calcined to produce an SCM with a clinker/cement factor as low as 0.5, while maintaining strength equivalent to that of pure Portland cement, says Sui. He predicts these options will partly replace conventional Portland cement in the years to come. “It is like vegetable producers, you need a whole range to meet all customers needs,” says Sui. “The future construction industry will have more tailor-made and specialised applications.”

ARTIFICIAL INTELLIGENCE AND CCS
Artificial intelligence (AI) is another solution gaining ground in China’s cement industry. Sophisticated systems use big data volumes to minutely control processes in ways that go beyond human capabilities, improving efficiency and reducing CO2 and other emissions. “In general, cement has been quite late in getting into AI, but there are clear benefits in new and established plants,” says Riley. A flagship factory integrating AI from the design phase for a clinker line with an output of 5000 tonnes a day, built by the China National Building Material company, was opened in 2015 for the company’s subsidiary China United Cement-Tai’an in Shandong province. And where residue CO2 emissions are unavoidable, the potential of carbon capture and storage or use is being explored. Anhui Conch hit the headlines in 2018 with the world’s largest pilot carbon capture and purification plant. It is early days though. The demonstration unit at its Baimashan plant in the city of Wuhu in Anhui province separates and purifies only 50,000 tonnes of the over one million tonnes of CO2 emitted from a cement kiln exhaust gas each year. Finding a profitable market on a large scale for the CO2 is not easy. “We need sustainable emissions mitigation and need to start right now, proceeding step by step. All these solutions are needed, there is no single answer, we need a broad package and we cannot wait,” says Sui.

TEXT Sara Knight