Bio-Energy Corn is Gasoline

At present, with the depletion of global fossil fuels such as oil and the rising average temperature, people are forced to look for alternative energy sources. Bioenergy derived from plants such as cellulose, cassava and algae seems to be a promising prospect for humans. - In the future, human beings will not rely on oil, coal and natural gas, but will rely on renewable sources of renewable energy. However, how far is the distance between a wonderful ideal and reality? Why has bio-energy so far only looked beautiful? Please follow the reporter to explore.

Bioenergy:

The best alternative to fossil fuels

Wang Tiejun, a researcher at the Key Laboratory of Renewable Energy and Gas Hydrates of the Guangzhou Institute of Energy Research of the Chinese Academy of Sciences, said in an exclusive interview with the newspaper that bioenergy is the only energy source that can be used as a substitute for chemicals or petroleum among all renewable energy sources. Other renewable energy sources, such as solar energy, wind energy, ocean energy, and nuclear energy, are all non-carbon energy sources and are mainly used in heat and electricity. Industry **To date, people have been relying on the use of fossil fuels containing carbon, such as oil, natural gas and coal, as energy sources for transportation and for the manufacture of chemicals such as rubber and plastics. Aside from non-renewable fossil energy, carbon sources are traced in all renewable energy sources. Biomass energy synthesized from carbon dioxide and water is a unique renewable energy source that can be used as a substitute for fossil energy.

In addition, from the perspective of ecological environment, the combustion of fossil and other energy sources such as oil will generate large amounts of carbon dioxide, which will endanger the environment, increase global temperatures, cause greenhouse effects, and endanger human safety. If biofuels come from plants, carbon dioxide is absorbed from the atmosphere during plant growth. Therefore, in theory, biofuels can reduce the accumulation of greenhouse gases in the atmosphere compared with burning fossil fuels.

Wang Tiejun said that at present, the focus of bio-energy research is to solve two problems, one is the problem of resources. From the perspective of the equivalent of agriculture and forestry (the amount of tons of standard coal equivalent), the amount of biomass in the world ranked fourth in energy reserves, second only to oil, coal and natural gas. However, the difficulty of development is that these resources are very fragmented and difficult to collect. The collection cost accounts for the largest proportion of the cost of bioenergy. During the "Twelfth Five-Year Plan" period, China will deploy and cultivate energy plants as raw materials for biological energy, such as the cultivation of energy plants on non-grain arable land in the western regions of China to solve resource problems.

Another focus of research is on new technology research and the realization of multi-channel conversion technologies. Current bioenergy conversion technologies include biological methods and thermochemical methods. The biological method is to convert biomass into sugar and ferment it with microorganisms to produce biogas, ethanol and other chemicals and liquid fuels. The chemical method is gasification of biomass into hydrogen, carbon monoxide and other biogas, and then it catalyzes the synthesis of liquid fuels through specific catalysts.

Turning waste into treasure:

"Garbage is a resource for misplaced places."

The richness of bio-energy raw materials makes it hard for us to imagine. Xie Yuyuan of the Guangzhou Institute of Energy Research at the Chinese Academy of Sciences told the reporter that the old director once said that there is actually no rubbish in the world. “The rubbish is just a misplaced resource.”

As far as raw materials are concerned, Wang Tiejun introduced that different bioconversion technologies have different applicable raw materials. In the case of biological methods, domestic carbohydrates, such as household waste, poultry excrement, and sugary industrial wastewater, such as kitchen waste, can be converted into biogas such as biogas. In the past, these fuels were used for energy applications such as heating, and now they can be purified, compressed, canned, and used as automotive fuels through large-scale production. This has entered the application demonstration stage in individual regions. In addition, plant cellulose such as straw can also be used to produce fuel ethanol, which is commonly known as ethanol gasoline. For example, five years ago, the country used Chenhualiang to produce ethanol gasoline. At present, people try to produce fuel ethanol mainly from non-food crops such as cassava, sweet potato, sweet sorghum, and straw.

The thermochemical method is mainly aimed at forestry and agricultural wastes such as trees, chips, straws, wheat, and cotton processed shells, and is pyrolyzed and gasified to make transportation fuels and high value-added chemical fuels. The thermochemical method requires that the raw material must be dry material, otherwise it may be because of the large moisture content of the material and the large energy consumption of the process, which affects the equipment.

In addition, liquid fuel can also be "harvested" from algae. Microalgae are the “giants” of photosynthesis. Some algae use up to 3% of incident sunlight, while corn or sugar cane is only about 1%. These algae can more efficiently convert water, carbon dioxide, and sunlight into oil, which can be further converted into hydrocarbon hydrocarbons.

If you want to describe a map of biomass energy conversion, Wang Tiejun said that the recent biomass energy conversion is still mainly for biogas applications, mainly for heat utilization, while the medium and long term is based on the application of liquid fuels and chemicals. Examples include the production of biodiesel, cellulose fuel ethanol, and the manufacture of chemicals such as rubber, plastics, and polymer materials.

One of the bottlenecks in the development of raw materials and high cost

The prospect of biofuels looks beautiful, but after years of research, it has not been able to replace oil to a large extent but has encountered a bottleneck.

Wang Tiejun introduced that currently the scientific community is studying fuel butanol, which has a higher calorific value than ethanol. Its performance is basically the same as that of regular gasoline. It can be mixed with gasoline in any ratio. The application of fuel butanol, which is still in the demonstration stage, is the future development trend. "No problem with biofuel performance, the key is cost," he said.

For biofuel companies, the restriction of raw materials is a major issue. Because bioenergy is different from coal, natural gas, and so on, its raw materials are decentralized and there is no place to store so much raw material. Therefore, the production capacity of related companies is mostly 10,000 tons and 100,000 tons, and will not reach the scale of 1 million tons. In foreign countries, some bioenergy farms are built in areas with wide land, but even if there is land cultivation, it is very difficult to collect raw materials. Assume that the radius of collection is 10 kilometers. To collect and process raw materials, it needs to go through such processes as harvesting, packing, transportation, and warehousing. Each of these procedures requires a lot of manpower and material resources, and the process consumes a lot of energy. If the scale of production is expanded and the radius of collection reaches 100 kilometers, the cost is even more disastrous. In order to obtain raw materials more easily, many bioenergy companies in China are located in rice processing, forestry and other processing bases, but are subject to high manufacturing costs, and there are no industrial giants in the bioenergy field.

In the United States, scientists, corporate CEOs, and government policy makers all have good intentions. The U.S. government has also invested a lot of money. But after decades of efforts, biofuels have not been able to compete with petrol on price so far. . Corn ethanol is now the only type of biofuel in the United States that has reached commercial production scale, thanks to the US government’s financial subsidies. According to the data from the US government audit department, only in 2010 was the corn subsidy of more than 5.68 billion U.S. dollars. In the absence of financial subsidies, corn ethanol cannot compete with gasoline on price.

Wang Tiejun said that with the development of science and technology in the future, the bioenergy field should also have the possibility of creating wealth myths. “At present, two difficulties are technically targeted: First, cheap biomass materials, and second, through the development of new technologies to reduce production costs.” To solve the cost problem, the cultivation of low-cost fuel plants is also a research focus.

The development bottleneck competes with people for food and struggles with food

In addition, the development of bio-energy should avoid the problem of competing with people for grain and land for food. The U.S. government stipulates that corn ethanol must account for 10% of the fuel used by passenger vehicles throughout the country. This policy has promoted a substantial increase in corn ethanol production from 50 million gallons in 1979 to 13 billion gallons in 2010. But the production of these 13 billion gallons of corn ethanol consumes about 40% of the US corn crop, which is grown on 130,000 square kilometers of farmland. In October 2010, the U.S. Congressional Research Service reported that even if all of the U.S. corn were used for the production of ethanol in 2009, its output could only replace 18% of U.S. gasoline consumption. The researchers concluded that it is impractical to attempt to significantly increase the energy security of the United States by increasing the production of corn ethanol. Moreover, if all the corn is used for production, people and livestock will have no food to eat.

In addition, even if only corn stover is used, sugar derived from cellulose is used to produce biofuels, and this method also imposes a burden on the environment and agriculture. After harvesting, corn stalks remain in the field, and decomposition can improve soil fertility, and towing will accelerate soil degradation. In Brazil, because sugar cane is easier to grow, they use sugar cane to replace corn stover to make ethanol. However, in order to obtain a large amount of sugarcane ethanol, people need to level up large-scale tropical rainforests to open up more sugarcane plants and intensify the damage to the original environment.

It can be seen that if corn and sugar cane continue to be used in large quantities to replace oil, it will further pressure the global agricultural system, and global agriculture is trying to provide food, clothing and feed for 7 billion people and livestock. Wang Tiejun said that in the United States, corn is mainly used to produce ethanol fuel, but this practice is strongly opposed in developing countries.

future

Can bioenergy completely replace fossil energy?

According to Wang Tiejun, as far as China is concerned, the application of bioenergy is currently less than 0.5% of national energy consumption. By 2020, biofuels such as ethanol fuel and butanol fuel are expected to replace 10 million tons of transportation fuel. The development of bioenergy and future market prospects will also be affected by fluctuations in fossil fuel prices such as oil.

At present, all the energy contained in the crop, including the plants consumed by livestock, and the trees used in pulp, paper, and other wood products, add up to about 1.8 trillion joules, equivalent to about 20% of the world's energy consumption. It will be impractical to increase this amount in the short term, and it may also cause serious ecological consequences. Researchers at Princeton University stated that the goal of bioenergy should be to produce certain special fuels, such as fuel for aircraft.

There is no end to the development of science. We need to give more patience to bio-energy to completely replace fossil resources.