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Could China adopt more ‘trees-to-power’ technology?

The ‘negative emissions’ technology BECCS could help the world reach carbon neutrality, but a lack of biofuels and space is hampering progress in China.

China has achieved great success in forestation. But what if you could continue growing trees to capture carbon from the atmosphere, burn the wood to generate power, and then capture the CO2 released during combustion for storage underground? It sounds like a possible route to carbon neutrality.

BECCS, or bioenergy with carbon capture and storage, also sounds too good to be true. But in its 2018 special report, the Intergovernmental Panel on Climate Change described carbon dioxide removal (CDR) technologies including BECCS as indispensable if warming is to be limited to 1.5C. CDR could offset remaining emissions from sectors where zero carbon is not feasible by absorbing between 100 billion and 1 trillion tonnes of CO2 by 2100.

Existing and potential CDR measures include forestation, land restoration and soil carbon sequestration, BECCS, direct air carbon capture and storage (DACCS), enhanced weathering and ocean alkalinisation. These vary widely in terms of maturity, potential, costs and risks, with only forestation and BECCS close to maturity.

Currently, China is not running BECCS trials, due to a lack of the necessary technology and biofuels. But in the future, when China has exhausted its options for emissions reduction, these negative emissions technologies may be needed to achieve carbon neutrality.

Issues with carbon capture and storage

In March, Wang Can, a professor at Tsinghua University’s School of Environment, wrote that research and trials of negative emissions technology are urgently required.

Both parts of BECCS – bioenergy (BE) and carbon capture and storage (CCS) – are essential.

Because of the costs involved, China has restricted trials in CCS technologies mostly to carbon capture, utilisation and storage projects, or CCUS, with the hope that cash flows from the utilisation component can help cover part of the costs of operating the technology.

In fact, six of the country’s eight operational CCS trials are CCUS projects based in the oil fields in China’s north, according to data from the Global CCS Institute. But even with cost reduction from more use, many CCS trials remain too expensive to operate in China. This limits China’s ability to test and improve key technological components of CCS in preparation for possible future deployment.  

The captured CO2 is mostly used for enhanced oil recovery. When oil wells become unproductive, it is possible to extend their life span by pumping in CO2 to force residual crude oil to come to the surface. The bulk of the CO2 remains sequestered below ground.

This is not an ideal technological path from the point of view of carbon neutrality: recovered oil ultimately gets burned and releases carbon again. But in the absence of massive government subsidies, CCUS is a relatively economic way of getting trials off the ground in China, allowing technological learning to happen.

In one of its reports, the Asian Development Bank estimated that overall CCS costs in China’s coal chemical industry could come close to zero, if the CO2 captured was sold to oil firms at around 100 yuan (US$15) per tonne.

But existing attempts at this kind of enhanced oil recovery don’t look promising as far as profitability is concerned. A research team led by Qin Jishun of the Research Institute of Petroleum Exploration and Development (RIPED) calculated that based on a 500,000-ton project in a Jilin oil field, profitability would require oil prices at $90 per barrel, a minimum 10 per cent bump in extraction rates and a stable supply of CO2.

But this March oil was trading at around $60 a barrel; CO2 enhanced oil recovery is on average increasing extraction rates by only 7.4 per cent, and there is no reliable and affordable supply of CCUS-sourced CO2.

The paper also points out that China’s CCUS trials are mostly small and of little commercial value. With no external pressures to reduce emissions, or policy support, oil firms have little incentive to roll out CCUS.

Li Jia, associate professor at the China-UK Low Carbon College at Shanghai Jiao Tong University, told China Dialogue that the high costs of carbon capture at coal-fired power plants means high prices for CO2. That makes oil firms unwilling to buy, and so it’s difficult to make it a commercial reality. “As far as I’m aware, there are no successful examples of partnerships between power plants and oil firms in China,” Li said.

Besides the difficulty of getting CCUS trials up and running, China is also struggling with other technological preparations.

A 2017 report on climate strategy pointed out that China was running very few trials of carbon storage in saline aquifers, the technology expected to become the country’s main option for large-scale geological carbon storage. Saline aquifers make up 95.6 per cent of this potential storage capacity, far more than oil, natural gas and coal gas fields. Trials in monitoring and early warning systems for carbon storage, and large-scale CO2 transportation have also been few and far between.

The only whole-process demonstration of carbon capture and storage in saline aquifers was built by China Shenhua Energy Company in Inner Mongolia in 2011. The project was designed to store 100,000 tonnes of CO2 per year. But according to one expert associated with the Global CCS Institute, who preferred to remain anonymous, the project has stopped operating due to bad economics.

The above-mentioned 2017 report on climate strategy recommended that China promote large-scale and whole-process CCUS trials between 2020 and 2030, run engineering trials of combined carbon capture and saline aquifer storage, and aim to capture 30-50 million tonnes of CO2 per year through CCUS by 2030.

The report referred to calculations by the Pacific Northwest National Laboratory and the Chinese Academy of Sciences’ Wuhan Institute of Rock and Soil Mechanics, which found the country could capture 3.8 billion tonnes of CO2, with enhanced oil recovery and saline aquifer storage able to sequester 1 billion and 100 billion tonnes respectively.

Even including projects that are not yet officially running, China’s CCS trial projects are capturing only 5.4 million tonnes of CO2 a year. Emissions, meanwhile, are around 10 billion tonnes. “If the government wants to use CCUS to reduce emissions on that scale, existing efforts are virtually negligible,” said the anonymous expert. “There are huge challenges for China if it wants to see that increase by orders of magnitude.”

Biofuel supply scarce

The “BE” part of BECCS is also a problem. Where should the biofuel come from? Using BECCS to meet the Paris Agreement’s 2C target would require 3 per cent of the freshwater currently appropriated for human use, 7–25 per cent of agricultural land, and 25–46 per cent of arable plus permanent crop area, according to a 2016 paper by Pete Smith et al, published in Nature magazine.

The supply of the biofuels BECCS requires (wood, straw, agricultural waste, algae) is constrained by the availability of land and freshwater, and the need to protect biodiversity.

Since 2006, China has committed to retaining 1.8 billion mu (1.2 million hectares) of arable farmland. And in 2011, the idea of ecological red lines was proposed to help preserve biodiversity. The work of defining those redlines is largely complete, with 25 per cent of China’s land and sea area now under legal protections.

“There’s only so much farmland, you can’t lose any. There’re only so many forests, you can’t lose those either. And some places are barren, you can’t grow biofuels there,” said the anonymous expert. “If you want to move forward with BECCS, you need to have the Ministry of Ecology and Environment and the Ministry of Natural Resources, which are responsible for the ecological redlines, sit down with the Ministry of Agriculture, which is responsible for the arable land red line. I fear it would be hard to bring them together just for CO2 removal. But if you don’t tackle the provision of land and water, and the impact on food, biofuel development is going to be limited.”

The biofuel-fired power generation is also expensive. Biofuels are less energy-dense than fuels such as coal, meaning larger quantities are needed to generate the same amount of electricity. Getting hold of biofuels in the first place is difficult.

Straw and other agricultural waste products have to be sourced from thousands of individual farms, and the processes of procuring, processing, storing and transporting account for much of the overall cost. In a recent paper, Liu Wei and others point out that burning biofuels for power generation is only 20 per cent energy efficient, and most biofuel power stations are making a loss.

Not yet the right time

So given these two constraints, what hope for BECCS in China?

The anonymous expert says that China’s focus now is on cutting emissions by improving energy efficiency and reducing energy use in sectors such as coal-fired power, steel and cement manufacturing, and oil and gas. “We should be starting with preventing emissions in the first place. Tech like CCS will come into play when all other approaches have been exhausted.” He expects to see CCUS used on a wide scale only after 2030, or even 2040.

Li Jia thinks it will be earlier, saying that during the 14th Five Year Plan period (2021–25), China will cut emissions from the electricity sector by expanding renewables such as wind and solar. Cities will only consider requiring CCUS installed at coal-fired power plants after they have reached peak carbon, according to Li. “Most Chinese cities are expected to see peak carbon earlier than the 2030 deadline,” she said, “so there may be a rush to roll out CCUS between 2025 and 2028.”

Regardless of which timetable you look at, BECCS is still some way off.

The anonymous expert said China needs more policies to help implement CCUS. “Currently there are expressions of support, but no actual measures.” Looking overseas, the US provides an economic incentive for firms to install CCUS tech, in the form of tax breaks. If China adopted a carrot and stick approach and provided subsidies like those for the wind and solar power sectors, a large-scale CCUS rollout would come much sooner.

Meanwhile, other research has found China lacks regulations governing CCS, again hampering its growth. For example, there are no laws on the ownership of subterranean spaces where CO2 might be stored; no norms for assessing the environmental impact of CCUS projects; or rules on long-term responsibilities for carbon sequestration sites. But long-term security of such sites is a challenge that must be considered.

When it comes to biofuel-fired power generation, Li Jia thinks that small-scale trials, with biofuel used to provide 5 per cent of the fuel for gigawatt-scale generators, would mean most power plants could find adequate biofuel supply within a radius of 20–50 kilometres, as China’s rural areas produce more straw and other agricultural waste than their overseas equivalents. But the government must put policies in place for such trading between farmers and power plants if those purchases are to actually happen.

The large scale roll-out of bioenergy-fired power generation is likely to pose challenges for China due to shortages of straw, and this could cause the government to consider the planting of other crops such as trees solely for biofuel production. But the demand for wood from the UK’s biggest BECCS plant, Drax, has already damaged biodiversity of natural forests in the US, where it sources its biofuel, with native hardwood species in the Deep South, such as the cherry bark oak, being systematically replaced by fast-growing pines, leading to criticism from environmentalists.

Chen Ying, a researcher with the Chinese Academy of Social Sciences’ Research Institute for Eco-civilisation, has said in an interview with China Dialogue that BECCS technology requires more mature and economic CCS technologies, and assurances sequestered carbon will not leak, along with minimised impacts on the environment. “There are a lot of issues and blanks, and early research and preparation are essential,” she said.

This article was originally published on China Dialogue under a Creative Commons licence.

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