Energy crops are renewable energy, inexhaustible. In addition to providing unlimited prospects for energy development and solving the energy demand crisis, they can also reduce the production of industrial waste, which is conducive to environmental protection.
Planted exclusively forenergyAs a work closely watched by people, the energy crisis is one of its main driving forces.In the energy crisis, most industrializationcountryOnly then did our agricultural sector realize its role.In thesecountryWithout support and protection for agriculture, more and more land will be abandoned.Therefore, it may be more realistic to convert some agricultural land into energy and industrial products.However, if the agricultural land is to be used to produce energy and industrial products successfully, it must not only meet the requirements of environmental protection, but also be economically reasonable.Modern agriculture increasingly depends on external inputs, especially energy, fertilizer andpesticidesAnd other high-energy commodities.
Chinese name
Energy crops
Foreign name
energy crop
Alias
Elephant grass
Advantages
mushroom
Main role
Provide people with a variety of chemicals and energy
As for the definition of energy crops, there are many expressions in the domestic literature from different perspectives.For example, all crops that can be effectively converted into energy substitutes can be called energy crops;Or, energy crops refer to all kinds of cultivated plants for the purpose of providing fuel raw materials or fuel oil.The director of the Agricultural Experiment Institute of the Taiwan Administrative Agriculture Commission summarized this concept from the perspective of emphasizing the convertibility of energy crops: energy crops refer to the way of energy production that can utilize crops to grow endlessly, and convert solar energy into chemical energy of plants (heat energy of fuel) through photosynthesis. This energy conversion can be carried out at normal temperature and pressure,It is a promising and efficient energy production method.[1]
Crop advantages
The ideal biofuel crop should have high photosynthetic efficiency.From the current situation,Miscanthus Crops can be regarded as an ideal biofuel crop."Mang".Native to North China and Japan, this plant has many advantages:
1. Rapid growth: it can grow 3 meters high in season, so the local people call it "elephant grass".
2. Spicy growth: This crop grows fromSubtropicalreachthe temperate zoneIt can grow everywhere in a wide area, and grows luxuriantly under strong sunshine and high temperature conditions, with high utilization rate of fertilizer and water.During the growth period, chemical fertilizers and pesticides can not be applied, and the powerful root system on its rhizome can effectively absorb nutrients.
3. Complete combustion: "awn" is drier than "awn" during harvest, and there will only be 20% - 30% water in the plant. How much does this crop absorb from the atmosphere during growthcarbon dioxideThe amount of carbon dioxide released during combustion does not increase the content of carbon dioxide in the atmosphere.
4. Low cost: The energy generated by awn crops is twice as much as the biodiesel produced by rapeseed, and its cost is less than 1/3 of that of planting rape.
5. High yield: According to the test, the yield of this biofuel crop is up to 44 tons per hectare.If the average annual "harvest" of 12 tons of oil per hectare is higher than any other existing energy plants, and it can be harvested continuously for many years.
Main role
Green plants will provide people with more and more diverseChemicalsAnd energy.Biodiesel refined from energy crops can replace oil and reduce human's excessive dependence on oil.Therefore, the development and planting of energy crops not only make energy renewable and comprehensive utilization, reduce environmental pollution, but also create opportunities for the recovery of agricultural economy.Energy crops will become another new way for human beings to develop renewable energy.
Energy crops are renewable energy, inexhaustible.Lin Qicong, a lecturer doctor of Oldenburg University in Germany, pointed out in the research results published in the Energy Quarterly that every hectare of rape can produce 1200 liters of vegetable oil and 1060 liters of oxygen (the amount of oxygen required by 40 people in a year). Vegetable oil is not only edible, but also can be converted into biodiesel through simple chemical reaction;Oxygen is good for purifying air.
The results show that biodiesel does not contain sulfide, so it will not form acid rain;In addition, it can avoid filling soil by biological decomposition.Groundwater pollution.At present, countries all over the world are moving to new energy, hoping to reduce greenhouse gas emissions while maintaining industrial development.
The planting and utilization of energy crops are of great significance to increase farmers' income and solve the problems of agriculture, rural areas and farmers.Land desertification, water and soil loss, pollution and other problems are very serious in China. The development and cultivation of energy crops suitable for China can effectively use degraded, returned farmland and wasteland that is not suitable for farming, which will greatly help ecological restoration.[2]
Common varieties
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sorghum
Sweet sorghum is a kind of energy crop with excellent characteristics. It has a broad development prospect to use sweet sorghum to produce fuel alcohol in China.[3]It has strong climate adaptability, simple planting method, good genetic variability, and many parts of the world have mastered the experience of planting sorghum.Sorghum is more resistant to drought than corn, and its water utilization efficiency is much higher than corn. When drought occurs, sorghum can remain in a "sleep" state, and it can quickly recover its vitality once the humidity increases.It also has strong soil adaptability and low requirements for nutrition.The yield of some hybrid varieties has reached 10t/hmtwoGrain, plus 100t/hmtwoGreen straw with high sugar content.Although the United States has carried out research on sugar sorghum for more than a century, it is relatively late to carry out research on syrup sorghum. The main purpose of this research is to produce edible syrup.Sorghum can also be used to produce ethanol, and ethanol can be used as the raw material for sugar production in the off-season.
Sugar cane
Sugar caneIt was earlier studied as an energy crop,[2]It is a crop that can grow in many parts of the world, and is traditionally used as the raw material for producing sugar and alcohol.In addition, it is also a potential cellulose raw material.Some high-yielding "energy type sugarcane" hybrids have been bred, and the experimental yield has reached 253t/hmtwo(about 76t/hmtwo）。AustraliaBy fermenting the sugar in sugarcane with their newly cultivated excellent sugarcane, each ton of sugarcane can produce 90L ethanol.Brazil has a high yield of sugarcane and a low cost of ethanol production. Its fuel ethanol has already entered commercial operation and has strong competitiveness.[2]In Brazil, there are 12 alcohol plants with the best benefits, and the output of sugarcane planted has reached 89t/hmtwoThe alcohol output per ton of sugarcane is 79L, which is equivalent to an annual alcohol output of more than 7000L per hectare of land.Jerusalem thistle (artichoke) is a tuberous plant, which originally grows in eastern North America.It has strong vitality and can tolerate harsh conditions, especially in dry, cold and relatively poor soil conditions. It is a good variety suitable for planting in poor areas.The tubers are rich in inulin, which can produce fructose under the action of acid or hydrolase, and then ferment fructose to produce ethanol.According to the test results of France and the United States, 85L ethanol can be produced per ton of tubers. If 40t tubers are produced per hectare, it is equivalent to 300-400L ethanol produced per hectare.
In addition, in addition to tubers, 7~8t dry leaf vines can be produced per hectare. Because they can be used as fuel, they can provide some energy for ethanol processing.Cassava has attracted worldwide attention as an alternative raw material for ethanol production, especially in Brazil and Australia.In Brazil, in order to promote ethanol production, cassava is used as a supplementary substitute for sugarcane, because cassava can be grown in acidic and barren land, while sugarcane can only grow in a more suitable environment.
vegetable oil
Vegetable oil (or mixed with diesel) can be used as fuel of internal combustion engine.A short-term evaluation test has been carried out on 40 different vegetable oils in internal combustion engines, including soybean oil, peanut oil, cottonseed oil, sunflower seed oil, rape oil, palm tung oil and castor oil.Many parts of the world have experience in planting sunflowers, so many experimental plans use sunflower seed oil.
The vegetable oil fuel industry can bring many important and attractive benefits, such as:
1. For most state-owned and private vegetable oil production plants, they can rapidly increase production once needed, often requiring only one growing season's advance preparation time.
2. Planting most oil crops only requires the same technology as planting common crops (such as corn).
3. The fuel produced by 1 hectare of good oil crops can meet the planting requirements of 8-20 hmtwoFuel for other crops.
4. Due to the simple technology of oil pressing and oil pumping, oil plants can be directly produced on farms, or on a cooperative scale or industrialized scale.
5. Most oil crops have strong adaptability and cold tolerance.
6. Vegetable oil is safe to store and use.
7. The by-products from oil pressing can often be used as high protein animal feed.Hydrocarbon producing plants have been proposed to directly use plants to produce gasoline and other hydrocarbons.For example, in order to extract hydrocarbons with molecular weight very close to petroleum and produce by-product sugar from Euphorbia Lathys, research on Euphorbia Lathys has been carried out in California.Under the condition of irrigation, each hectare of land can obtain 2t oil and 5t sugar every year.In order to evaluate the economic feasibility of this method, at least five attempts have been made in other parts of the world, but the results obtained by different researchers are different.
Switchgrass
Switchgrass(Scientific name:Panicum virgatum），Perennial herbPlant, easy to reproduce, with thick grass stalks, up to 3m high.Switchgrass is an ideal energy crop with strong adaptability, large yield potential and environmental friendliness.[4]Distributed onU.S.ATexasGrassland area toCanada, can be used for refiningethanolFuel.
Switchgrass is a native plant in North America, so it does not need fertilization and irrigation. If a large number of crops such as corn are planted in North America, it can reduce the impact of agriculture on ecology and help wild animals such as birds.The biomass of switchgrass is up to 20t/hmtwoIt has strong adaptability to poor soil, and its perennial characteristics reduce management intensity and investment.[2]
As one of the energy crops, switchgrass has the following characteristics:
1. Cellulosic ethanolCellulose ethanol can reduce carbon emissions more than corn ethanol.The cost of growing switchgrass is cheaper than planting corn;However, the current productionCellulosic ethanolThe cost of is still relatively high.
2. Direct combustionSwitchgrass can be directly burned to obtain energy. At present, there are ways to overcome air pollution. Switchgrass can replace (part of) coal.
3. Water and soil conservationSwitchgrass has deep roots and can be used for water and soil conservation.Planting switchgrass can also increase the content of soil organic matter.
4. FeedSwitchgrass is an excellent cattle feed, but it is toxic to horses, sheep and goats.
biodiesel
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Biodiesel is a so-called "clean and safe" new fuel that can replace petrochemical diesel by using renewable resources such as vegetable oil or animal oil.Compared with traditional petrochemical fuels, biodiesel has the characteristics of renewable, easy biodegradation, low combustion pollution emissions, etc.Therefore, some countries regard biodiesel as the key direction of bioenergy development.
At present, the EU is the main region in the world to develop and apply biodiesel.According to relevant EU materials, the development of biodiesel in the EU has not only the consideration of ensuring energy security, but also the intention of protecting the environment and reducing greenhouse gas emissions.About 90% of EU's greenhouse gas emissions come from the transportation industry.As per《Kyoto Protocol》According to the regulations, the EU will reduce the number ofcarbon dioxideEmissions.It is estimated that it is very difficult for the EU to complete this indicator during this period.
The EUBiomass fuelAs a major alternative energy source.According to the EU Biofuels Strategy, the proportion of biomass fuels in all fuels in EU countries will increase from 2% in 2005 to 5% in 2010?75%, 10% in 2020.The EU plans to achieve the goal of 25% biomass fuel in transportation fuel by 2030.The biomass fuel developed by EU mainly uses rapeseed to develop biodiesel.In 2007, the EU produced about 8 million tons of biodiesel. It is estimated that the production capacity of biodiesel will reach 13.5 million tons in 2010.This means that EU countries must expand the planting area of rapeseed and increase the production of rapeseed to provide more raw materials for biodiesel development.At present, Germany has planted more than 1 million hectares of rapeseed specially used to produce biodiesel.
In short, with the increase of population, peopleDietary structureAnd the development of biomass energy with food as raw material, the demand for food consumption will continue to increase.according toFAOAccording to the prediction made before 2000, the world food demand is expected to increase by 2030Annual average growth rate13%, equivalent to the growth rate of grain production;It is predicted that the world's total demand for food for various purposes will increase from 1864 million tons in 1999 to 2830 million tons in 2030, of which the demand for edible food will increase from 1003 million tons in 1999 to 1406 million tons in 2030;It is estimated that the total food demand of developing countries for various purposes will increase from 1129 million tons in 1999 to 1917 million tons in 2030, of which the demand for edible food is expected to increase from 790 million tons in 1999 to 1185 million tons in 2030;It is estimated that the average annual growth rate of world feed grain demand will be 19% from 1999 to 2015 and 15% from 2015 to 2030.However, the prediction of FAO is somewhat sluggish after all, lagging behind the actual increase of food consumption demand. At that time, the world did not use food to develop biomass energy on a large scale, so it is estimated that the average annual growth rate of world food demand will be 13% by 2030, slightly lower than the actual growth rate of food consumption demand.The United States alone will consume 100 million tons of corn according to the biomass energy development plan by about 2020, and the actual consumption will be more.Therefore, the future tense pattern of world food supply and demand has initially taken shape, and the world food crisis is just a "short and concentrated" reflection of this pattern.
Utilize technology
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Biomass energy resourcesThere are many kinds and technologies.Biomass energy includes crop stalks, forestry residues, oil plants, energy crops, domestic garbage and other organic wastes.
At present, the amount of crop straw resources that can be used as energy each year is about 150 million tons of standard coal, the amount of forestry surplus resources is about 200 million tons of standard coal, and the potential planting area of oil plants and energy crops such as jatropha curcas, rapeseed, castor, sumac, pistachio chinensis and sweet sorghum can meet the annual output of 50 million tonsBioliquid fuelRaw material demand.In theory, the amount of industrial organic wastewater and livestock farm wastewater can produce nearly 80 billion cubic meters of biogas, equivalent to 57 million tons of standard coal.According to the current technical situation of biomass energy utilization in China, the focus of biomass energy utilization will be biogas, biomass power generation, biomass liquid fuel, etc.
biogas technology
The biogas utilization technology in China is basically mature, especially household biogas, which has a development history of decades.Since 2003, rural household biogas construction has been included in the national debt project, and the annual investment of the central financial fund has exceeded 2.5 billion yuan. With the strong promotion of government policies, household biogas has formed a scale market and industry;Since 2000, large and medium-sized biogas projects such as livestock farms, food processing, distilleries, and urban sewage treatment plants have also begun to develop. By the end of 2008, about 30 million rural household biogas digesters, 140000 biogas digesters for domestic sewage purification, more than 2700 livestock farms and industrial wastewater biogas projects have been built nationwide, with an annual biogas output of about 10 billion cubic meters,It has provided high-quality living fuel for nearly 80 million rural people.At the same time, with the continuous progress and improvement of biogas technology, China's household biogas systems and components have basically achieved standardized production and professional construction. In most areas, biogas technology service organizations have been established, with strong technical service capabilities.The process technology of large and medium-sized biogas projects is mature, and a professional design and construction team has been formed. The service system is basically complete, and the conditions for large-scale development have been met.
Biopower generation
Energy crops are the basic link of biomass energy development,[2]In addition to biogas, the application of other biomass energy technologies in China is still in the initial stage of industrialization.In terms of biomass power generation, we have basically mastered technologies such as agricultural and forestry biomass power generation, urban garbage power generation, and biomass dense briquette fuel, but the current development and utilization scale still needs to be expanded.By 2006, the installed capacity of biomass power generation in China had exceeded 2.2 million kW, including 1.7 million kW for bagasse, 50000 kW for rice husk, and 400000 kW for urban waste incineration. In addition, there are some small-scale demonstration projects of biomass gasification power generation.By the end of 2008, more than 1.5 million kilowatts had been put into production.In terms of biomass gasification and landfill gas power generation, more than 100000 kilowatts were put into production in 2007, and 200000 kilowatts were under construction.At present, more than 10 biomass direct fired power generation projects are under construction nationwide, with an installed capacity of more than 200000 kilowatts.The installed capacity of the mixed combustion project is about 500000 kilowatts.However, to achieve the development goals of 5 million kW and 30 million kW of biomass power generation in 2010 and 2020, there are still problems to be solved, such as resource dispersion, high cost of raw material collection, continuity and assurance of raw material supply.
Bioliquid fuel
In terms of bio liquid fuel, in order to alleviate the contradiction between oil supply and demand, the state actively promotes the research and development of bio liquid fuel technology and pilot demonstration work.During the "Tenth Five Year Plan" period, the state approved the construction of four pilot projects for the production of biofuel ethanol with aged grain as raw material, forming an annual production capacity of 1.02 million tons. Since 2004Heilongjiang, JilinLiaoning、Henan、Anhui5 provinces andHebei、Shandong、Jiangsu、Hubei27 prefectures and cities in 4 provinces carried out the pilot work of ethanol gasoline for vehicles, and the output reached 1.65 million tons in 2006.Since 2007, the country has begun to restrict the production of fuel ethanol using grain as raw material, and the development momentum of fuel ethanol has slowed down.In the near future, the key technology research and development direction of China's biological liquid fuel is to use non grain raw materials (mainly sweet sorghum, cassava and lignocellulose) to produce fuel ethanol technology, and toJatropha curcasAnd other oil-bearing crops as raw materialsBiodiesel technologyAnd build a large-scale raw material supply baseBiomass liquid fuelProcessing enterprises.At present, small-scale experiments have been carried out to produce biodiesel from sweet sorghum and cassava as raw materials and jatropha curcas as raw materials, which has accumulated experience for large-scale development and utilization of biological liquid fuel in China.It is estimated that by 2010, the annual production capacity of fuel ethanol will reach about 2 million tons, and the annual production capacity of biodiesel will reach 200000 tons, replacing a total of 2 million tons of refined oil annually.At the same time, some enterprises in China are researching and developing bio liquid fuel technology with straw, wood and other non grain raw materials, and have made some breakthroughs, which is expected to form large-scale production capacity around 2010.However, in general, the development of biomass power generation and bio liquid fuel, whether to achieve the goals of the long-term development plan of renewable energy, is fraught with difficulties.
Main problems
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In fact, even though it is widely used in the United Statestransgenic technologyProduction of corn for ethanol fuel processing, but in the current situation of tight arable land supply and frequent drought and other disasters, the prospect of significantly increasing corn production is still not optimistic.Even if the US corn production increases in the next 20 years, the demand for corn processing ethanol fuel may grow faster than the corn production.Therefore, the supply and demand of the world corn market will remain very tense in the future.
It is foreseeable that corn prices will remain high for a long time in the future.This is a terrible thing for developing countries with insufficient food production and supply capacity.This may lead to the soaring price of corn, and drive the price of all food varieties to rise, which will then be transmitted to the livestock production field. The price of meat will also rise, and the world inflation seems to be in front of us.
What needs to be added is that in addition to producing ethanol fuel, the United States is one of the first countries to develop biodiesel and carry out commercial applications.The commercial application of biodiesel in the United States can be traced back to the early 1990s.In order to promote the application of biodiesel in our country, the United States formulated a corresponding biodiesel standard in 1998 to strictly regulate the production and use of biodiesel.As of April 2005, there were more than 60 biodiesel production enterprises in the United States, including those to be built, with an annual production capacity of nearly 1 million tons.According to the plan of the United States, its biodiesel production capacity will reach 1.15 million tons by 2011 and 3.3 million tons by 2016.According to its natural resource endowment, soybean is the main raw material for biodiesel production in the United States.Soybean oil is the main edible oil in developing countries.In recent years, the price of soybean and oil has been rising, which is closely related to the development and application of biodiesel in the United States.
Demonstration base
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In July 2007, the Ministry of Agriculture issued the Development Plan for Agricultural Biomass Energy, which proposed that by 2010, a number of agricultural biomass energy demonstration bases should be built, key technologies in some fields should reach the international advanced level, the degree of industrialization should be significantly improved, the scope and scale of agricultural waste utilization should be significantly expanded, and the structure of rural domestic energy consumption should be significantly optimized,Farmers' income from agricultural biomass energy industry has been increasing
The proportion and status of agricultural biomass energy in national energy consumption are rising.By 2015, a number of agricultural biomass energy bases will be built, the technological innovation and industrial development system will be basically completed, the cost of development and utilization will be significantly reduced, and the marketization of agricultural biomass energy industry will initially be realized.Biomass energy industry has become an important field of agricultural development, which can promote farmers' income increase, improve rural living conditionsNew socialist countrysideIt plays an increasingly important role in ensuring national energy security and protecting the ecological environment.By 201O, the total number of rural household biogas in China will reach 40 million (18 million new households), accounting for about 30% of the suitable farmers, and the annual production of biogas will reach 15.5 billion cubic meters;By 2015, the total number of rural household biogas will reach about 60 million, the annual production of biogas will be about 23.3 billion cubic meters, and the industrialization of biogas will be gradually promoted.In, 4000 large-scale breeding farms and biogas projects in breeding communities were newly built, with an annual increase of 336 million cubic meters of biogas;By 2015, 8000 large-scale breeding farms and breeding community biogas projects will be built, with an annual biogas production of 670 million cubic meters.
Development prospect
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Face problems
Energy security and food security are two major issues facing mankind.However, China's national conditions are different. China has more people and less land, and the pressure of food security exists for a long time. Therefore, China cannot develop energy crops at the expense of food security, which requires us to follow a path of biomass energy development with Chinese characteristics.Always adhere to the basic principle of "not competing with people for food, not competing with food for land".Specifically, we should grasp three aspects:
First, we should strictly control the use of corn, oilseeds and other crops to produce biomass raw materials.
Second, insist on making full use of straw and livestock manure waste to develop biogas, gasification and solidification of straw, and partial replacementFossil energy。
Third, on the premise of not competing with grain for land, moderately develop energy crops and produce biomass raw materials.[5]
development potential
China still has great potential in the utilization of rural waste.In China, 700 million tons of crop straw, nearly 3 billion tons of livestock manure and 360 million tons of rural garbage are produced every year. These are the huge potential of developing biomass energy.At present, we have explored some successful ways. For example, in recent years, we have been vigorously developing the rural biogas industry in rural areas, and transforming livestock manure and even domestic garbage into energy for production and living.By the end of 2007, the number of rural biogas users had reached 26.5 million, with an annual biogas production of 10.2 billion cubic meters.What is the concept of 10.2 billion cubic meters?Equivalent to 16 million tons of standard coal, equivalent to more than 44 million tons of emission reductioncarbon dioxide。This is the largest and most realistic biomass energy.[5]
