Energy crops
Introduction
An energy crop is a plant grown as a low-cost and low-maintenance harvest used to make biofuels, such as bioethanol, or combusted for its energy content to generate electricity or heat. Energy cropsare generally categorized as woody or herbaceous plants; many of the latter are grasses (Graminaceae).
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.
Type of energy crops
1. Solid biomass
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.
2. Gas biomass (methane)
Anaerobic digesters or biogas plants can be directly supplemented with energy crops once they have been ensiled into silage. The fastest growing sector of German biofarming has been in the area of "Renewable Energy Crops" on nearly 500,000 ha of land (2006) Energy crops can also be grown to boost gas yields where feedstocks have 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.
3. Liquid biomass
Biodiesel
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 attra
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Energy crops their worldwide usage Data and
1. Energy crops
Introduction
An energy crop is a plant grown as a low-cost and low-maintenance harvest used to
make biofuels, such as bioethanol, or combusted for its energy content to generate electricity or
heat. Energy cropsare generally categorized as woody or herbaceous plants; many of the latter
are grasses (Graminaceae).
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.
Type of energy crops
1. Solid biomass
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.
2. 2. Gas biomass (methane)
Anaerobic digesters or biogas plants can be directly supplemented with energy crops once they
have been ensiled into silage. The fastest growing sector of German biofarming has been in the
area of "Renewable Energy Crops" on nearly 500,000 ha of land (2006) Energy crops can also be
grown to boost gas yields where feedstocks have 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.
3. Liquid biomass
Biodiesel
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
3. preventative of the spread of disease such as clubroot. Biodiesel yield of soybeans is
significantly lower than that of rape
Typical oil extractable by weight
Crop Oil %
copra 62
castor seed 50
sesame 50
groundnut kernel 42
jatropha 40
rapeseed 37
palm kernel 36
mustard seed 35
sunflower 32
palm fruit 20
soybean 14
4. Bioethanol
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.
Energy
There are two key indicators when evaluating various crops for biofuel: fuel yield per acre and
net energy yield of the biofuel, minus energy used in production and refining. This table
compares crops. The energy content of ethanol is about 67 percent that of gasoline. The energy
content of biodiesel is about 90 percent that of petroleum diesel
Ethanol and Biodiesel Yield per Acre from Selected Crops
Fuel Crop Fuel Yield (gallons)
Ethanol
Sugar beet (France) 714
Sugarcane (Brazil) 662
Cassava (Nigeria) 410
Sweet Sorghum (India) 374
Corn (U.S.) 354
5. Wheat (France) 277
Biodiesel
Oil palm 508
Coconut 230
Rapeseed 102
Peanut 90
Sunflower 82
Soybean 56
Top 3 energy crops
1. Sugar cane: If there is one country that has done the most to wean itself from oil and
increase its use of biofuel, it is Brazil. The South American country started going green after
the 1973 Middle East oil embargo reduced shipments of oil worldwide. When the price of oil
climbed, the Brazilian government encouraged its farmers to plant more sugarcane. They
then processed that sugarcane into ethanol. Brazil invested billions of dollars to make the
transition and eventually sugarcane ethanol became less expensive than gasoline. By the mid-
1980s, every driver in Brazil was driving a vehicle that was ethanol-powered. Today, almost
all cars in Brazil have "flexible" fuel engines that can run on either gasoline or ethanol.
Brazil's climate is well suited to growing sugarcane. However, producing ethanol from
sugarcane is six times less expensive than producing ethanol from corn. Growing sugarcane
requires fewer chemicals, including pesticides and fertilizers. But when harvesting
6. sugarcane, farmers must burn their fields, which spew massive amounts of greenhouse gases
into the atmosphere
The share of sugar cane to be used for ethanol production at the worldwide level is
expected to reach almost 35% in 2019.
7. Climatic Requirement for Sugarcane Cultivation:
1. Sugarcane is a tropical crop.
2. It requires warm and humid climate for growth while cool, sunny and dry climate for ripening.
3. The temperature requirement is 20 0 C to 26 0 C.
4. Germination does not take place when temperature goes below 7 0 C.
5. Both the extremes of temperature is harmful.
6. Severe cold arrests the growth, while attack of stem borer increases in hot weather.
7. It requires more than 1,375 mm annual rainfall when grown as rainfed crop.
8. Rainfall deficiency produces a fibrous cane, whereas too heavy rainfall reduces sugar content.
2. Wheat: When it comes to ethanol production in the United States, wheat is corn's ugly
stepsister. While refineries produce ethanol from various types of "feedstock," including
wheat and barley, roughly 90 percent of America's ethanol comes from wheat. Ethanol is
mainly used to power motor vehicles and is often blended with gasoline. In Europe, however,
using wheat as an energy crop is on the rise. Great Britain's first wheat-based ethanol plant,
which opened in 2010, is expected to produce 106 million gallons (4 million liters) of the
biofuel each year. The company expects to use about 1.2 million tons (907.18 kilograms) of
wheat annually. Many people are concerned that growing wheat as an energy crop will divert
the grains needed for food. Researchers from the University of Illinois say food prices spike
when farmers grow wheat and corn for use as a biofuel
In the news Biofuels plant opens to become UK's biggest buyer of wheat
8. Just in UK alone, the HGCA identified planned ethanol production by end of next year
requiring over 6mT of wheat or 12 billion of those family loaves.
The UK has been exporting just 1mT of wheat from its average national wheat crop of 15mT
over the last five years . No wonder, The Times pointed out last autumn that the UK is
heading for a wheat deficit, starting this year, as a new ethanol plant of Teesside starts
consuming 1.2 mT of wheat annually.
3. Corn
World map of total biofuel production by region
9. The National Corn Growers Association’s annual report reveals statistics about U.S. corn
production, including the amount of corn used for ethanol production and the amount of distillers
grains that goes back into the feed market.
10. The 2012 World of Corn shows 5 billion bushels of the current supply of corn is being used for
ethanol, and 1.547 billion bushels of that re-enters the feed market. That includes distillers grains
and corn gluten for domestic use and a smaller amount of DDGS for export.
Ecological Requirements
Soils: Maize can grow on a wide range of soils though it performs best in well drained and well
aerated loam or silty loams or alluvial soils with a pH of 5.5 – 7. It is intolerant of water logging.
Altitude: It can grow in a wide range of agro-ecological zones in Kenya ranging from 0-2200 M
Above Sea Level depending on variety. Very low or high altitudes results in poor yields.
Temperature: The optimum temperatures for good yields is 300C. Cold conditions extends the
maturity period whereas high temperatures lower the yields.
Rainfall: Maize grows well with 600 – 900mm of rainfall. The rainfall should be well
distributed throughout the growing period. The rainfall is most critical at flowering and silking
stage. Drought at flowering time interferes with pollination and drastically reduces yield.
Towards harvesting, dry conditions are required to facilitate drying of the grain.
References:
http://www.thecropsite.com/articles/1781/biofuel-production-greater-shares-of-commodities-
used/
http://www.nafis.go.ke/agriculture/maize/ecological-requirements/
http://www.actionaid.org.uk/blog/campaigns/2010/03/29/wheat-biofuels-laughing-gas-and-
fizzy-drinks