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Sweet Sorghum : A New “Smart Biofuel Crop”

In these days of soaring food prices around the world, a smart crop that provides food and fodder, grows in dry, salty or soggy conditions, tolerates heat, provides steady income for poor farmers, and can be used to produce ethanol. Sweet sorghum, a plant that grows to a height of 12 feet and looks like corn without the ears, has all these qualities.

“Sweet sorghum [Sorghum bicolor (L.) Moench] provides an opportunity for poor farmers to participate in the biofuel bonanza,” says Dr. William Dar, director general of the International Crops Research Institute for the SemiArid Tropics (ICRISAT), one of the 15 allied centers supported by the Consultative Group on International Agricultural Research (CGIAR).

“We consider sweet sorghum an ideal `smart crop’ because it produces food as well as fuel.” Dr. Dar adds.

In partnership with Rusni Distilleries and some 1,500 farmers in Andhra Pradesh, India, ICRISAT helped build and operate the world’s first commercial bioethanol plant using locally produced sweet sorghum as feedstock. The plant, which began operations in June 2007, produces about 40 kiloliters (10,568 gallons) of ethanol daily.

The process is simple. To produce ethanol, the sorghum stalks are crushed yielding sweet juice that is distilled and transformed into biofuel, a clean burning fuel with a high octane rating.

The grain is not involved in the ethanol process. It is used for food, mainly in flat breads and porridges.

The crushed stalks are used for animal fodder.

“By linking the distillery with sorghum farmers, we have helped smallholder farmers improve their incomes by more than $40 per acre and maintain a secure food supply at the same time,” says Dr. Dar. “It is a sustainable use of the entire sweet sorghum plant.”

Similar public-private-farmer partnership projects with ICRISAT, local industries and farmers are also underway in the Philippines, Mexico, Mozambique and Kenya, as countries search for alternative fuels.

India intends to use a 10 percent ethanol blend to save an estimated 80 million liters (21 million gallons) of gasoline each year to ease the country’s growing need for gasoline and to reduce carbon emissions.

Sweet sorghum costs $1.74 to produce a gallon of ethanol, compared with $2.19 for sugarcane and $2.12 for corn.

It also compares well on energy balance, with 8 units of energy produced for every unit of energy invested in its cultivation and production, compared with 8.3 units for sugarcane and 1.8 for corn. On the other hand, only 0.8 unit of energy produced in fossil fuel production for every unit invested.

Because the grain of sweet sorghum is not used in the ethanol production, it does not have any impact on food prices and food security. With corn and sugar cane, it is the opposite. In the United States, this diversion of corn from food and fodder has produced an increase in bread, meat and egg prices.

“As an added benefit, dry land farmers in the tropics can get three sweet sorghum crops a year, versus only one for corn and sugarcane,” says Belum V .S. Reddy, ICRISAT’s principal sorghum breeder.

The plant thrives at daytime temperatures of 90 degrees Fahrenheit. However, in temperate climates, sorghum farmers rarely get more than one crop a year.
It is also easier and cheaper to grow sweet sorghum than other biofuel crops.

For example, it requires one-eighth the amount of water compared to sugarcane and about half that required to grow corn; sorghum requires only half as much fertilizer as corn.

Besides low water requirements, sorghum grows readily in saline or alkaline soils. It can withstand stress and is inexpensive to cultivate.

Ethanol produced from sweet sorghum is carbon neutral. The carbon dioxide fixed during the growing cycle offsets the carbon dioxide produced during crop production, processing, and ethanol utilization. And, since sweet sorghum thrives on marginal lands, the need to clear rainforests or use productive cropland is reduced.

Sweet sorghum will not replace sugar cane in parts of the developing world where those crops are well established, emphasizes Dr. Reddy. However, the need for irrigation and high rainfall makes it difficult to expand sugar cane production without moving into ecologically sensitive areas like rainforests.

Sorghum is the world’s fifth largest grain crop-behind rice, corn, wheat and barley. It is grown on more than 42 million hectares (107 million acres) in 99 countries. India, the United States, Nigeria, China, Mexico, Sudan and Argentina are the leading producers.
As a start, about 1,600 hectares are already planted with sweet sorghum in India that could be used for bioethanol production. The area is expected to rapidly increase even in other countries.

According to ICRISAT scientists, an estimated 50 percent of the grain sorghum area -11.7 million hectares (28.9 million acres) in Asia and 23.4 million hectares (57.8 million acres) in sub-Saharan Africa, could be sown with sweet sorghum.

Since sweet sorghum has almost equal yields of grain as in grain sorghum and significantly higher stalk yields. “No food production would be forfeited by switching from regular sorghum to sweet sorghum,” says Dr. Reddy.

ICRISAT scientists have been working for 15 years to develop varieties of sweet sorghum that would contribute to a reliable and steady supply of sweet juice for ethanol production.

The varieties of sweet sorghum being used are sensitive to the length of daily sun light and temperature changes. Different plant types take different number of days to flower and mature and therefore produce various amounts of juice at different times of the year, hence, the stalk supply cannot be predicted” says Dr. Reddy. ICRISAT’s efforts are to help provide a consistent supply by developing photoperiod – insensitive hybrids (flowering and maturity less influenced by day length and temperature changes) that can be planted any time during the year.

Until recently, lack of steady sorghum feedstock throughout the year has blocked India’s efforts to expand ethanol production.

The distillery at the Mohammed Shahpur Village in the Medak district of Andhra Pradesh, India opened in October 2006 and now produces some 40 kiloliters (10,568 gallons) of ethanol every day from locally grown sweet sorghum and some other feedstock.

In India, by planting sweet sorghum instead of grain sorghum, farmers earn about $200 per acre per season, compared to about $165 per acre from grain sorghum.

Harvesting and processing the stalks also provides about 40,000 person days of labor a year at the distillery at the Mohammed Shahpur Village. Sweet sorghum was planted last year on about 1,500 acres in the region with planned expansion to 2,000 acres to provide feedstock for the prototype distillery.

Last November, ICRISAT and TATA Chemicals, part of one of India’s largest commercial enterprises, formed a Sweet Sorghum Ethanol Research Consortium. Under their agreement, ICRISAT will supply seeds for sweet sorghum varieties and hybrids along with technical support for farmers. TATA will contract local farmers to produce sweet sorghum on nearly 10,000 acres in Maharashtra and initially build a plant capable of producing up to 30 kiloliters (7,926 gallons) of ethanol a day.

In the public-private-farmer partnership model developed by ICRISAT, scientists develop sweet sorghum hybrids and test new cultivars with smallholder farmers. Distilleries provide farmers with improved seed and technical advice, offer a guaranteed price for the crops and transport the harvested stalks for processing. The goal is to develop a competitive biofuel industry that benefits the rural poor and is environmentally sustainable.

ICRISAT’s public-private-farmer partnership serves as a model for other parts of the developing world. ICRISAT has agreements with five private companies in the Philippines to form a consortium to grow sweet sorghum and produce ethanol, with similar consortia being formed in Uganda, Nigeria, Mozambique and South Africa.

Interest in sweet sorghum’s ethanol potential is not confined to the developing world. An International Conference on Sorghum for Biofuel, sponsored by the Office of International Research Programs of the U.S. Department of Agriculture and Texas A&M, will be held in Houston, Texas, in August 2008.

Amidst today’s soaring food and oil prices, sweet sorghum is indeed a smart crop as it contributes to household food security and helps livelihoods of the rural poor in the semi-arid tropics, now populated by about a billion people the poorest of the poor.