Energy crop
Encyclopedia
An energy crop is a plant
grown as a low cost and low maintenance harvest
used to make biofuel
s, or combusted for its energy content to generate electricity or heat. Energy crops are generally categorized as woody or herbaceous (grassy).
Commercial energy crops are typically densely planted, high yielding crop species where the energy crops will be burnt to generate power. Woody crops such as Willow or Poplar are widely utilised, as well as temperate grasses such as Miscanthus
and Pennisetum purpureum (both known as elephant grass). If carbohydrate content is desired for the production of biogas
, whole-crops such as maize
, Sudan grass
, millet
, white sweet clover
and many others, can be made into silage and then converted into biogas.
Through genetic modification and application of biotechnology
plants can be manipulated to create greater yields, reduce associated costs and require less water. However, high energy yield can be realized with existing cultivars.
Energy generated by burning plants grown for the purpose, often after the dry matter is pelletized. Energy crops are used for firing power plants, either alone or co-fired with other fuels. Alternatively they may be used for heat or combined heat and power
(CHP) production.
. The fastest growing sector of German biofarming has been in the area of "Renewable Energy Crops" on nearly 500,000 ha land (2006). Energy crops can also be grown to boost gas yields where feedstocks have a low energy content, such as manures and spoiled grain. It is estimated that the energy yield presently of bioenergy crops converted via silage to methane is about 2 GWh/km². Small mixed cropping enterprises with animals can use a portion of their acreage to grow and convert energy crops and sustain the entire farms energy requirements with about 1/5 the acreage. In Europe and especially Germany, however, this rapid growth has occurred only with substantial government support, as in the German bonus system for renewable energy.Similar developments of integrating crop farming and bioenergy production via silage-methane have been almost entirely overlooked in N. America, where political and structural issues and a huge continued push to centralize energy production has overshadowed positive developments.
European production of biodiesel
from energy crops has grown steadily in the last decade, principally focused on rapeseed
used for oil and energy. Production of oil/biodiesel from rape covers more than 12,000 km² in Germany alone, and has doubled in the past 15 years. Typical yield of oil as pure biodiesel may be is 100,000 L/km² or more, making biodiesel crops economically attractive, provided sustainable crop rotations exist that are nutrient-balanced and preventative of the spread of disease such as clubroot
. Biodiesel yield of soybeans is significantly lower than that of rape.
Energy crops for biobutanol are grasses. Two leading non-food crops for the production of cellulosic bioethanol
are switchgrass
and giant miscanthus.
There has been a preoccupation with cellulosic bioethanol in America as the agricultural structure supporting biomethane is absent in many regions, with no credits or bonus system in place. Consequently a lot of private money and investor hopes are being pinned on marketable and patentable innovations in enzyme hydrolysis and the like and therefore America is viewed by some technology planners as falling further behind Europe in real bioenenergy gains.
Bioethanol also refers to the technology of using animal and human grains, principally corn (maize seed) to make ethanol directly through fermentation, a process that is widely reputed to consume as much energy as it produces, therefore being non-sustainable. New developments in converting grain stillage (referred to as distillers grain stillage or DGS) into biogas energy looks promising as a means to improve the poor energy ratio of this type of bioethanol process. 2007 saw a setback in the economics of building grain refineries in the USA while the shipment of grains and ethanol by rail car has prompted the train industries largest growth phase since 50 years.
energy crops as giant miscanthus, switchgrass
, jatropha
, fungi, and algae
.
Also byproducts (green waste
) of food and non-food energy crops can be used to produce biofuels.
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
grown as a low cost and low maintenance harvest
Harvest
Harvest is the process of gathering mature crops from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper...
used to make biofuel
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
s, or combusted for its energy content to generate electricity or heat. Energy crops are generally categorized as woody or herbaceous (grassy).
Commercial energy crops are typically densely planted, high yielding crop species where the energy crops will be burnt to generate power. Woody crops such as Willow or Poplar are widely utilised, as well as temperate grasses such as Miscanthus
Miscanthus
Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one species Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one...
and Pennisetum purpureum (both known as elephant grass). If carbohydrate content is desired for the production of biogas
Biogas
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung, and kitchen waste can be converted into a gaseous fuel called biogas...
, whole-crops such as maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, Sudan grass
Sudan grass
Sudan grass, , is a species of grass raised for forage and grain, native to tropical and subtropical regions of Eastern Africa. The plant is cultivated in Southern Europe, South America, Central America, North America and Southern Asia, for forage or as a cover crop.It is distinguished from the...
, millet
Millet
The millets are a group of small-seeded species of cereal crops or grains, widely grown around the world for food and fodder. They do not form a taxonomic group, but rather a functional or agronomic one. Their essential similarities are that they are small-seeded grasses grown in difficult...
, white sweet clover
Melilotus albus
Melilotus albus , is a legume sometimes grown for forage. White sweet clover is a major source of nectar for an apiary...
and many others, can be made into silage and then converted into biogas.
Through genetic modification and application of biotechnology
Biotechnology
Biotechnology is a field of applied biology that involves the use of living organisms and bioprocesses in engineering, technology, medicine and other fields requiring bioproducts. Biotechnology also utilizes these products for manufacturing purpose...
plants can be manipulated to create greater yields, reduce associated costs and require less water. However, high energy yield can be realized with existing cultivars.
Solid Biomass
Note: The terms biofuel, biomass, and so on, are often used interchangeably.Energy generated by burning plants grown for the purpose, often after the dry matter is pelletized. Energy crops are used for firing power plants, either alone or co-fired with other fuels. Alternatively they may be used for heat or combined heat and power
Combined Heat and Power
Combined Heat and Power may refer to:* Cogeneration* Combined Heat and Power Solar...
(CHP) production.
Gas biomass (Methane)
Anaerobic digesters or biogas plants can be directly supplemented with energy crops once they have been ensiled into silageSilage
Silage is fermented, high-moisture fodder that can be fed to ruminants or used as a biofuel feedstock for anaerobic digesters. It is fermented and stored in a process called ensiling or silaging, and is usually made from grass crops, including corn , sorghum or other cereals, using the entire...
. The fastest growing sector of German biofarming has been in the area of "Renewable Energy Crops" on nearly 500,000 ha land (2006). Energy crops can also be grown to boost gas yields where feedstocks have a low energy content, such as manures and spoiled grain. It is estimated that the energy yield presently of bioenergy crops converted via silage to methane is about 2 GWh/km². Small mixed cropping enterprises with animals can use a portion of their acreage to grow and convert energy crops and sustain the entire farms energy requirements with about 1/5 the acreage. In Europe and especially Germany, however, this rapid growth has occurred only with substantial government support, as in the German bonus system for renewable energy.Similar developments of integrating crop farming and bioenergy production via silage-methane have been almost entirely overlooked in N. America, where political and structural issues and a huge continued push to centralize energy production has overshadowed positive developments.
Biodiesel
European production of biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
from energy crops has grown steadily in the last decade, principally focused on rapeseed
Rapeseed
Rapeseed , also known as rape, oilseed rape, rapa, rappi, rapaseed is a bright yellow flowering member of the family Brassicaceae...
used for oil and energy. Production of oil/biodiesel from rape covers more than 12,000 km² in Germany alone, and has doubled in the past 15 years. Typical yield of oil as pure biodiesel may be is 100,000 L/km² or more, making biodiesel crops economically attractive, provided sustainable crop rotations exist that are nutrient-balanced and preventative of the spread of disease such as clubroot
Clubroot
Clubroot is a common disease of cabbages, radishes, turnips and other plants belonging to the family Cruciferae . It is caused by Plasmodiophora brassicae, which was once considered a slime mold but is now put in the group Phytomyxea. It has as many as nine races. Gall formation or distortion takes...
. Biodiesel yield of soybeans is significantly lower than that of rape.
Typical oil extractable by weight
| Crop | Oil % |
|---|---|
| copra Copra Copra is the dried meat, or kernel, of the coconut. Coconut oil extracted from it has made copra an important agricultural commodity for many coconut-producing countries. It also yields coconut cake which is mainly used as feed for livestock.-Production:... |
62 |
| castor Castor oil plant The castor oil plant, Ricinus communis, is a species of flowering plant in the spurge family, Euphorbiaceae. It belongs to a monotypic genus, Ricinus, and subtribe, Ricininae. The evolution of castor and its relation to other species are currently being studied.Its seed is the castor bean which,... seed |
50 |
| sesame Sesame Sesame is a flowering plant in the genus Sesamum. Numerous wild relatives occur in Africa and a smaller number in India. It is widely naturalized in tropical regions around the world and is cultivated for its edible seeds, which grow in pods.... |
50 |
| groundnut Peanut The peanut, or groundnut , is a species in the legume or "bean" family , so it is not a nut. The peanut was probably first cultivated in the valleys of Peru. It is an annual herbaceous plant growing tall... kernel |
42 |
| jatropha Jatropha Jatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female... |
40 |
| rapeseed Rapeseed Rapeseed , also known as rape, oilseed rape, rapa, rappi, rapaseed is a bright yellow flowering member of the family Brassicaceae... |
37 |
| palm Arecaceae Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates... kernel |
36 |
| mustard seed Mustard seed Mustard seeds are the small round seeds of various mustard plants. The seeds are usually about 1 or 2 mm in diameter. Mustard seeds may be colored from yellowish white to black. They are important spices in many regional foods. The seeds can come from three different plants: black mustard , brown... |
35 |
| sunflower Sunflower Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads... |
32 |
| palm Arecaceae Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates... fruit |
20 |
| soybean Soybean The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses... |
14 |
| cotton Cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal.... seed |
13 |
Bioethanol
Energy crops for biobutanol are grasses. Two leading non-food crops for the production of cellulosic bioethanol
Cellulosic ethanol
Cellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants.It is a type of biofuel produced from lignocellulose, a structural material that comprises much of the mass of plants. Lignocellulose is composed mainly of cellulose, hemicellulose and lignin...
are switchgrass
Switchgrass
Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico...
and giant miscanthus.
There has been a preoccupation with cellulosic bioethanol in America as the agricultural structure supporting biomethane is absent in many regions, with no credits or bonus system in place. Consequently a lot of private money and investor hopes are being pinned on marketable and patentable innovations in enzyme hydrolysis and the like and therefore America is viewed by some technology planners as falling further behind Europe in real bioenenergy gains.
Bioethanol also refers to the technology of using animal and human grains, principally corn (maize seed) to make ethanol directly through fermentation, a process that is widely reputed to consume as much energy as it produces, therefore being non-sustainable. New developments in converting grain stillage (referred to as distillers grain stillage or DGS) into biogas energy looks promising as a means to improve the poor energy ratio of this type of bioethanol process. 2007 saw a setback in the economics of building grain refineries in the USA while the shipment of grains and ethanol by rail car has prompted the train industries largest growth phase since 50 years.
By dedication
Dedicated energy crops are non-foodFood
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
energy crops as giant miscanthus, switchgrass
Switchgrass
Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico...
, jatropha
Jatropha
Jatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female...
, fungi, and algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
.
Also byproducts (green waste
Green waste
Green waste is biodegradable waste that can be composed of garden or park waste, such as grass or flower cuttings and hedge trimmings, as well as domestic and commercial food waste...
) of food and non-food energy crops can be used to produce biofuels.
See also
- Agricultural byproduct
- Algal fuel
- Anaerobic digestionAnaerobic digestionAnaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/or to release energy....
- BiogasBiogasBiogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung, and kitchen waste can be converted into a gaseous fuel called biogas...
- Biotech crop
- Cellulosic ethanolCellulosic ethanolCellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants.It is a type of biofuel produced from lignocellulose, a structural material that comprises much of the mass of plants. Lignocellulose is composed mainly of cellulose, hemicellulose and lignin...
- non food cropsNon Food CropsThe term non food crop applies to the use of agricultural crop for uses other than human or animal consumption .The range of crops with non-food uses is broad...
- Short rotation coppiceShort rotation coppiceShort Rotation Coppice is coppice grown as an energy crop. This woody solid biomass can be used in applications such as district heating, electric power generating stations, alone or in combination with other fuels.- Species used :...
- Short rotation forestryShort rotation forestryShort Rotation Forestry is grown as an energy crop for use in power stations, alone or in combination with other fuels such as coal. It is similar to historic fuelwood coppice systems.- Species used :...
- Table of biofuel crop yieldsTable of biofuel crop yieldsThe following table shows the vegetable oil yields of common energy crops associated with biodiesel production.This is unrelated to ethanol production, which relies on starch, sugar and cellulose content instead of oil yields....
- Vegoil
- MyriophyllumMyriophyllumMyriophyllum is a genus of about 69 species of freshwater aquatic plants, with a cosmopolitan distribution. The center of diversity for Myriophyllum is Australia with 43 recognized species...
External links
- Energy Crops for Fuel.
- Energy crops at Biomass Energy Centre.
- Center for Sustainable Energy Farming