The Past, Present and Future of Ethanol Production for Energy in China

By Ashlee Bushee

November 16, 2022
The Past, Present and Future of Ethanol Production for Energy in China

What Drives Ethanol Demand?

China is currently the third largest producer of ethanol (4% of global production) a year, which is far behind the United States (54%) and Brazil (30%) as the first and second producers. China’s crude oil consumption reached 648 million tons (2018) and 70% of this is depended on outside suppliers. It is anticipated that at the current consumption rates the global supply of crude oil, liquid hydrocarbons, and biofuels are expected to last through 2050. If petroleum resources last until 2050, it will depend on how much additional consumption countries will use with rising wealth and accelerated use in response to climate change events. Earlier this year India reopened 100 coal mines that went into rapid production to have enough energy to make it through a summer heat wave. From personal experience living through the polar vortex that hit Texas early 2021, the impact of that storm resulted in not only additional fuel to provide heat for homes designed for hot climates, but also the additional fuel to manufacture, deliver and install new pipes, furniture, carpets etc. that were destroyed when pipes burst as a result of the power grid failure and unexpected cold temperatures. The estimated cost to repair from this storm was $20 billion. As a result of uncertainty in oil and in climate events, China seeks to expand its production and use of ethanol energy in an attempt to have a more secure energy future that doesn’t compromise the food supply. In this article I will provide a brief introduction into the rise of the ethanol industry in China and then their hope to utilize crop straw as a cellulosic feedstock to meet demands.]

Four Stages of Ethanol Implementation in China

China is considered to have entered into ethanol production at a late stage. When they began investing in ethanol research in 2002 the U.S. and Brazil were already mass producers (which is in part what has led to the large gaps in output).

  • Pilot Phase, 2001-2003. Ethanol production is researched to address four primary concerns: a large surplus of wheat and corn, improve the quality of the ecological environment, find energy alternatives, and improve value of agriculture.

The outcome of this initial phase was to pilot vehicles in two provinces that used 10% anhydrous ethanol in the fuel. The 1990 Clean Air Act (RFG Fuel) and the Renewable Fuel Standard set forth in the Energy Independence and Security Act of 2007 are two legislative policies on the U.S. front that resulted in cars using E10 or E15 fuel. The Bush administration was widely ridiculed for this as people assumed that this would result in a direct increase in the price of foods that also came from corn.

Four Stages of Ethanol Implementation in China

  • Promotion and Development Phase, 2004-2006. Ethanol advances from research to larger production and 30 cities in China start manufacturing it. This phase is supported by the National Development and Reform Commission and the Ministry of Finance which results in ethanol plants having financial support even if they report a loss. Research is still underway for the development of non-grain ethanol plants including sorghum, fibrous materials, and cellulosic.

China appears on the world ethanol production map with 416 million gallons produced; a small number in comparison to Brazil with 6 billion gallons.

  • Iteration and Improve Phase, 2007-2012. Having early signs of government support to create and grow the ethanol industry it reinvigorates its initial plan with an emphasis on ethanol as a means to promote energy conservation, reduce greenhouse gases, and mitigate climate change. Goals were set to utilize 10% renewable fuels by 2010, and grow outputs by 10 million tons. Administration focuses on food security push for a non-grain bioethanol and the creation of a lignocellulosic (using straw and other abundant grasses) refinery plant.

Administration focuses on food security push for a non-grain bioethanol

  • Expansion Phase, 2013 – current. Achieve full coverage of vehicles using ethanol gasoline and advance large-scale production of cellulosic ethanol and the industries around it to gain more market share. There was a focus on using the cassava, straw, and steel industrial tail gas as feedstocks to manufacture ethanol.

When ethanol became an area to explore in the early 2000’s, ethanol from food sources were heavily subsidized by the Ministry of Finance at close to $480 per ton of ethanol. For comparison, in the U.S. the ethanol industry has been subsidized at close to a $900 per ton. As food security took priority in China the subsidy was gradually reduced until it was cancelled in 2016, and subsidies for non-food and cellulosic materials started to increase in 2012 until it reached a peak around 2016 at $154 per ton of ethanol. Production in China has only hit close to 30% of the target over the past few years, but has a projected capacity of 32 million tons of ethanol production. Missing these targets has prompted leaders to consider the industry as a whole and the impact of raw material supply and land use. A recent study funded by National Wildlife Federation and the U.S. Department of Energy, found that because of the land use changes to grow corn, along with processing it is actually 24% more carbon intensive than gasoline.

land use changes to grow corn, along with processing it is actually 24 percent more carbon intensive than gasoline

Waste Materials for a New Process

Because of the raw material supply constraints for starch and sugar cane, China is exploring using straw which is a byproduct of the agriculture industry as a feedstock. Agriculture activity in China has had a continuous increase from 2004 to 2015 and has increased from 685.95 million tons of straw in 2005 to 897.06 million tons in 2016. This raw feedstock is processed similar to a starch or sugar that under goes fermentation plus a few additional steps for preparation and needed alternative microbes for fermentation. The straw, lignocellulosic biomass, is more resistant to degradation than starch or corn and the pretreatment process reduces the degree of polymerization and crystallinity and increases the surface area. This initial step accounts for about 20% of the cost, but this step will increase the output of step 2 enzymatic hydrolysis. There are 4 modes of pretreatment physical, chemical, physiochemical or biological. Physical treatments often require a high amount of fuels to power the process of degradation through grinding, milling or radiation treatments. Chemical treatments are effective but often require high heat, a lot of water, corrosion and difficulty in recovery. Currently physiochemical and biological pretreatments are being studied for their potential to obtain the desired results, but researchers are hesitant that biological treatments are scalable.

The second step enzymatic hydrolysis adds cellulase (the enzyme) and lignocellulose is hydrolyzed to form the fermentable sugars for ethanol production. This step accounts for 20-50% of the cost.  Now that the original straw material has been broken down into hexose (mainly glucose) and pentose (mainly xylose), the ethanol fermentation process begins. Starch and sugar ethanol fermentation use saccharomyces cerevisiae, or Zymomonas mobilis, and can metabolize glucose into ethanol very efficiently. These can’t metabolize pentose and alternative strains are needed.  Researchers have engineered strains S. cerevisiae, Z. mobilis, and Escherichia coli which can metabolize hexose and pentose.  The last step is to distill out the ethanol from other products in the fermentation process.

Although using cellulosic material (straw) requires pretreatment processes with advanced technology this could be a viable pathway for China to grow their bio-ethanol industry that starts from the waste of the agricultural industry. This could align with their goals to create bio-ethanol to improve the quality of life and not restrict food supply. The United States and Brazil might also have to look for more viable means of production as land, water and chemical use become more regulated.

Terms

Enzymatic Hydrolysis: Enzymatic hydrolysis is the process in which cellulases are added to hydrolyze pretreated lignocellulosic biomass into fermentable sugars. (sciencedirect.com)

 

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