Brazilian scientists identify elephant grass as a promising biomass crop; first projects already underway
Studies by the Agrobiology Centre at the state Brazilian Agricultural Research Corporation (Embrapa) are finding that elephant grass has great potential as a biomass crop that can be used for the production of green heat, power and electricity. A Brazilian company, Sykue Bioenergia, has already commissioned a first thermoelectric power plant that will be fuelled by the grass. It plans another 10 and aims for carbon credits. The market for the solid biofuel is potentially huge, as it can further be used in the iron, steel, aluminum, chemical and cement industries. Moreover, the highly efficient crop can be grown across the tropics, opening major perspectives for clean development and new export markets in the developing world. Experts see the emergence of a global solid biofuel market, similar to that of liquid biofuels.
Biomass champion
Elephant grass (Pennisetum purpureum - earlier post) is a species of grass native to the tropical grasslands of Africa. It is a tall perennial plant, growing to 2-4.5m tall (sometimes up to 7.5 m), with razor-sharp leaves 30-120 cm long and 1-5 cm broad. It is a cane-like species of grass which utilizes the efficient C4 carbon fixation path, resulting in high biomass productivity. When burned in biomass power plants it can generate 25 times as much energy as the amount of fossil fuel used to produce it. In short, the crop has an extremely strong energy balance. (Compare with the energy balance of corn ethanol, which is around 1 to 1, or sugarcane ethanol at 8 to 1).
The biomass crop can be used as an alternative to coal, which is fetching record prices (earlier post). As a solid biofuel it can be burned either in dedicated, highly efficient biomass power plants, in blast furnaces as an alternative to coal, or co-fired with coal in existing power plants.
According to Vicente Mazzarella, who has been studying elephant grass at the Sao Paulo state government’s Institute for Technological Research (IPT) since 1991, the crop is a champion when it comes to sheer biomass yields. Compare it with the popular eucalyptus tree, planted in Brazil to produce cellulose and charcoal: the tree yields around 7.5 tons of dry biomass per hectare a year and up to 20 tons a year in optimum conditions, while elephant grass yields 30 to 40 tons.
Furthermore, eucalyptus trees take seven years to reach a size worth felling, while elephant grass can be harvested two to four times a year, because of its rapid growth.
And its yield may be increased still further, since the species has hardly been studied and no genetic improvement efforts have yet been carried out. There are close to 200 varieties of elephant grass, and it will take time and effort to identify which ones are best suited to different soil and climate conditions.
Crop research
After 10 years of research, Embrapa’s Agrobiology Centre identified three varieties of elephant grass suited to energy production purposes because of their high yield without nitrogenous fertilisers. For use as a biofuel, the least nutritious varieties are sought, in contrast to its traditional use as animal feed:
energy :: sustainability :: renewable :: coal :: cement :: iron :: steel :: biomass :: elephant grass :: energy balance :: co-firing :: pellets :: Brazil ::
The reason is that nutrients like mineral salts produce ash that can damage iron and steel furnaces, Bruno Alves, an agronomist with the elephant grass research team at Embrapa’s Agrobiology Centre, headed by Segundo Urquiaga.
That is why tests were done using varieties that grow in poor soil, using the minimum amount of fertilisers, but still producing the highest yields of biomass.
The conversion of energy intake into energy storage (the energy balance) of the plant can be improved by biological nitrogen fixation, in which bacteria take nitrogen from the air and convert it to compounds that fertilise plants.
This is an area in which Embrapa’s Agrobiology Centre has accumulated much expertise in the last few decades, inoculating nitrogen-fixing bacteria into beans and sugarcane.
Biological nitrogen fixation limits itself to the nitrogen required by the plant, avoiding the risk of excessive nitrogenous fertiliser use, said Alves. He pointed out that nitrogenous fertilisers require the greatest amount of fossil fuel energy to produce them chemically, and that by avoiding its use, greenhouse gas emissions are also avoided.
Logistics, bioconversion
But elephant grass does present certain difficulties. It likes a lot of water, so its tolerance of the long dry seasons of the Cerrado, the Brazilian savannah where the largest extensions of land are available for cultivation, must be studied, as well as whether it will maintain its productivity level with less humidity.
Drying and compacting the biomass are also a challenge. Green elephant grass is 80 percent water, and it does not dry out in the sun, as eucalyptus does, but rots if left in piles. To dry, it must be cut up into small pieces, and some heat energy applied. Compacting is necessary for storage and transport because of the great bulk of the dry grass.
The ceramic industry, therefore, is likely to be the first user of elephant grass as an energy source. Medium-sized ceramic plants require less than 100 hectares of elephant grass grown nearby, which dispenses with compacting and transport. The dried elephant grass can be used in furnaces directly, instead of wood or natural gas. Other processes needing just heat or steam will soon be able to make use of this alternative fuel.
First grass powered station
A medium-sized electricity company, Sykue Bioenergia, has already commissioned a thermoelectric power plant that will be fuelled by elephant grass. The thermoelectric station will be built in Sao Desiderio in the state of Bahia in northeastern Brazil, by Dedini, an industrial company better known for building sugar mills and distilleries.
The Sykue power plant will cost 80 million reais (43 million dollars) and is due to come onstream in December 2008. It will have a capacity of 30 megawatts and will produce its own elephant grass on a plantation of 4,000 hectares. The company intends to build 10 such power plants soon.
Ana Maria Diniz of Sykue Bioenergia said grass had been chosen to power the new generating plant “due to its capacity to transform solar energy into cellulose via a totally clean, renewable and economically viable production cycle.”
The project will allow carbon credits of a million tons per year to be obtained, which can be sold on the international market to generate extra profits for the companies involved.
Huge market
Making charcoal from elephant grass, to substitute for coke or traditional charcoal made from wood, still needs further research. But environmental pressures and the threat of an energy deficit in Brazil may accelerate its development and stimulate investment from large steelworks and energy companies.
The potential demand for this alternative energy source is huge, said Mazzarella, who indicated five big markets. As well as steelworks interested in a new charcoal that does not contribute to deforestation, there is a group of large consumers of energy, such as the aluminium industry, the chemical and cement industries, and electricity distributors.
Biomass energy implies a key saving for electricity companies because it can supply extra electricity at times of peak demand, which is the most expensive to produce.
The mining industry, which imports coal to process iron ore into iron and steel for export, could use elephant grass compressed into pellets, similar to wood pellets, in its blast furnaces as an economical and environmentally friendly solution.
In Europe, the use of dry, compacted biomass pellets for heating is growing rapidly (earlier post, here and here), and elephant grass could open up export markets for Brazil similar to those for ethanol, Mazzarella said.
References:
IPS: Pasto elefante, nuevo campeón en biomasa - October 2007.
Fuel Alternative: Brazil to produce power from grass - July 24, 2007.
Biopact: E.ON UK submits application for 25MW biomass plant - July 20, 2007
Biopact: Biomass pellets revolution in Austria: 46% less costly than heating oil; most efficient way for households to reduce carbon footprint - October 06, 2007
Biopact: Report: biomass fastest growing renewable in EU, largest potential - September 15, 2007
Biopact: Interpellets 2007: conference looks at wood pellets as an alternative to fossil fuels - August 16, 2007
Article continues
Biomass champion
Elephant grass (Pennisetum purpureum - earlier post) is a species of grass native to the tropical grasslands of Africa. It is a tall perennial plant, growing to 2-4.5m tall (sometimes up to 7.5 m), with razor-sharp leaves 30-120 cm long and 1-5 cm broad. It is a cane-like species of grass which utilizes the efficient C4 carbon fixation path, resulting in high biomass productivity. When burned in biomass power plants it can generate 25 times as much energy as the amount of fossil fuel used to produce it. In short, the crop has an extremely strong energy balance. (Compare with the energy balance of corn ethanol, which is around 1 to 1, or sugarcane ethanol at 8 to 1).
The biomass crop can be used as an alternative to coal, which is fetching record prices (earlier post). As a solid biofuel it can be burned either in dedicated, highly efficient biomass power plants, in blast furnaces as an alternative to coal, or co-fired with coal in existing power plants.
According to Vicente Mazzarella, who has been studying elephant grass at the Sao Paulo state government’s Institute for Technological Research (IPT) since 1991, the crop is a champion when it comes to sheer biomass yields. Compare it with the popular eucalyptus tree, planted in Brazil to produce cellulose and charcoal: the tree yields around 7.5 tons of dry biomass per hectare a year and up to 20 tons a year in optimum conditions, while elephant grass yields 30 to 40 tons.
Furthermore, eucalyptus trees take seven years to reach a size worth felling, while elephant grass can be harvested two to four times a year, because of its rapid growth.
And its yield may be increased still further, since the species has hardly been studied and no genetic improvement efforts have yet been carried out. There are close to 200 varieties of elephant grass, and it will take time and effort to identify which ones are best suited to different soil and climate conditions.
Crop research
After 10 years of research, Embrapa’s Agrobiology Centre identified three varieties of elephant grass suited to energy production purposes because of their high yield without nitrogenous fertilisers. For use as a biofuel, the least nutritious varieties are sought, in contrast to its traditional use as animal feed:
energy :: sustainability :: renewable :: coal :: cement :: iron :: steel :: biomass :: elephant grass :: energy balance :: co-firing :: pellets :: Brazil ::
The reason is that nutrients like mineral salts produce ash that can damage iron and steel furnaces, Bruno Alves, an agronomist with the elephant grass research team at Embrapa’s Agrobiology Centre, headed by Segundo Urquiaga.
That is why tests were done using varieties that grow in poor soil, using the minimum amount of fertilisers, but still producing the highest yields of biomass.
The conversion of energy intake into energy storage (the energy balance) of the plant can be improved by biological nitrogen fixation, in which bacteria take nitrogen from the air and convert it to compounds that fertilise plants.
This is an area in which Embrapa’s Agrobiology Centre has accumulated much expertise in the last few decades, inoculating nitrogen-fixing bacteria into beans and sugarcane.
Biological nitrogen fixation limits itself to the nitrogen required by the plant, avoiding the risk of excessive nitrogenous fertiliser use, said Alves. He pointed out that nitrogenous fertilisers require the greatest amount of fossil fuel energy to produce them chemically, and that by avoiding its use, greenhouse gas emissions are also avoided.
Logistics, bioconversion
But elephant grass does present certain difficulties. It likes a lot of water, so its tolerance of the long dry seasons of the Cerrado, the Brazilian savannah where the largest extensions of land are available for cultivation, must be studied, as well as whether it will maintain its productivity level with less humidity.
Drying and compacting the biomass are also a challenge. Green elephant grass is 80 percent water, and it does not dry out in the sun, as eucalyptus does, but rots if left in piles. To dry, it must be cut up into small pieces, and some heat energy applied. Compacting is necessary for storage and transport because of the great bulk of the dry grass.
The ceramic industry, therefore, is likely to be the first user of elephant grass as an energy source. Medium-sized ceramic plants require less than 100 hectares of elephant grass grown nearby, which dispenses with compacting and transport. The dried elephant grass can be used in furnaces directly, instead of wood or natural gas. Other processes needing just heat or steam will soon be able to make use of this alternative fuel.
First grass powered station
A medium-sized electricity company, Sykue Bioenergia, has already commissioned a thermoelectric power plant that will be fuelled by elephant grass. The thermoelectric station will be built in Sao Desiderio in the state of Bahia in northeastern Brazil, by Dedini, an industrial company better known for building sugar mills and distilleries.
The Sykue power plant will cost 80 million reais (43 million dollars) and is due to come onstream in December 2008. It will have a capacity of 30 megawatts and will produce its own elephant grass on a plantation of 4,000 hectares. The company intends to build 10 such power plants soon.
Ana Maria Diniz of Sykue Bioenergia said grass had been chosen to power the new generating plant “due to its capacity to transform solar energy into cellulose via a totally clean, renewable and economically viable production cycle.”
The project will allow carbon credits of a million tons per year to be obtained, which can be sold on the international market to generate extra profits for the companies involved.
Huge market
Making charcoal from elephant grass, to substitute for coke or traditional charcoal made from wood, still needs further research. But environmental pressures and the threat of an energy deficit in Brazil may accelerate its development and stimulate investment from large steelworks and energy companies.
The potential demand for this alternative energy source is huge, said Mazzarella, who indicated five big markets. As well as steelworks interested in a new charcoal that does not contribute to deforestation, there is a group of large consumers of energy, such as the aluminium industry, the chemical and cement industries, and electricity distributors.
Biomass energy implies a key saving for electricity companies because it can supply extra electricity at times of peak demand, which is the most expensive to produce.
The mining industry, which imports coal to process iron ore into iron and steel for export, could use elephant grass compressed into pellets, similar to wood pellets, in its blast furnaces as an economical and environmentally friendly solution.
In Europe, the use of dry, compacted biomass pellets for heating is growing rapidly (earlier post, here and here), and elephant grass could open up export markets for Brazil similar to those for ethanol, Mazzarella said.
References:
IPS: Pasto elefante, nuevo campeón en biomasa - October 2007.
Fuel Alternative: Brazil to produce power from grass - July 24, 2007.
Biopact: E.ON UK submits application for 25MW biomass plant - July 20, 2007
Biopact: Biomass pellets revolution in Austria: 46% less costly than heating oil; most efficient way for households to reduce carbon footprint - October 06, 2007
Biopact: Report: biomass fastest growing renewable in EU, largest potential - September 15, 2007
Biopact: Interpellets 2007: conference looks at wood pellets as an alternative to fossil fuels - August 16, 2007
Article continues
Wednesday, October 10, 2007
Report: increase in corn ethanol production could significantly impact water quality and availability in the United States
A National Research Council committee was convened to look at how shifts in the nation's agriculture to include more energy crops, and potentially more crops overall, could affect water management and long-term sustainability of biofuel production. Based on findings presented at a July colloquium, the committee came to several conclusions about biofuel production and identified options for addressing them. The results are published in a report titled 'Water Implications of Biofuels Production in the United States'.
In terms of water quantity, the committee found that agricultural shifts to growing corn and expanding biofuel crops into regions with little agriculture, especially dry areas, could change current irrigation practices and greatly increase pressure on water resources in many parts of the United States. The amount of rainfall and other hydroclimate conditions from region to region causes significant variations in the water requirement for the same crop, the report says. For example, in the Northern and Southern Plains, corn generally uses more water than soybeans and cotton, while the reverse is true in the Pacific and mountain regions of the country.
Water demands for drinking, industry, and such uses as hydropower, fish habitat, and recreation could compete with, and in some cases, constrain the use of water for biofuel crops in some regions. Consequently, growing biofuel crops requiring additional irrigation in areas with limited water supplies is a major concern, the report says (map shows the number of planned ethanol facilities, their water requirements and the availability of water - click to enlarge).
Even though a large body of information exists for the the United States' agricultural water requirements, fundamental knowledge gaps prevent making reliable assessments about the water impacts of future large scale production of feedstocks other than corn, such as switchgrass and native grasses. In addition, other aspects of crop production for biofuel may not be fully anticipated using the frameworks that exist for food crops. For example, biofuel crops could be irrigated with wastewater that is biologically and chemically unsuitable for use with food crops, or genetically modified crops that are more water efficient could be developed.
The quality of groundwater, rivers, and coastal and offshore waters could be impacted by increased fertilizer and pesticide use for biofuels, the report says. High levels of nitrogen in stream flows are a major cause of low-oxygen or "hypoxic" regions, commonly known as "dead zones," which are lethal for most living creatures and cover broad areas of the Gulf of Mexico, Chesapeake Bay, and other regions. The report notes that there are a number of agricultural practices and technologies that could be employed to reduce nutrient pollution, such as injecting fertilizer below the soil surface, using controlled-release fertilizers that have water-insoluble coatings, and optimizing the amount of fertilizer applied to the land:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: corn :: fertilizer :: nitrogen :: water :: United States ::
A possible metric to gauge the impact of biofuels on water quality could be to compare the amount of fertilizers and pesticides used on various crops, the committee suggested. For example, corn has the greatest application rates of both fertilizer and pesticides per acre, higher than for soybeans and mixed-species grassland biomass. The switch from other crops or noncrop plants to corn would likely lead to much higher application rates of highly soluble nitrogen, which could migrate to drinking water wells, rivers, and streams, the committee said. When not removed from water before consumption, high levels of nitrate and nitrite - products of nitrogen fertilizers - could have significant health impacts.
Nutrient and sediment pollution in streams and rivers could also both be attributed to soil erosion. High sedimentation rates carry financial consequences as they increase the cost of often-mandatory dredging for transportation and recreation. The committee observed that erosion might be minimized if future production of biofuels looks to perennial crops, like switchgrass, poplars or willows, or prairie polyculture, which could hold the soil and nutrients in place better than most row crops. The committee also identified other ways that farming could be improved, such as conservation tillage and leaving most or all of the cornstalks and cobs in the field after the grain has been harvested.
For biorefineries, the water consumed for the ethanol production process - although modest compared with the water used growing biofuel crops - could substantially affect local water supplies, the committee concluded. A biorefinery that produces 100 million gallons of ethanol a year would use the equivalent of the water supply for a town of about 5,000 people. Biorefineries could generate intense challenges for local water supplies, depending on where the facilities are located. However, use of water in biorefineries is declining as ethanol producers increasingly incorporate water recycling and develop new methods of converting feedstocks to fuels that increase energy yields while reducing water use, the committee noted.
The study was sponsored by the McKnight Foundation, Energy Foundation, National Science Foundation, U.S. Environmental Protection Agency, and National Research Council Day Fund. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, nonprofit institutions that provide science, technology, and health policy advice under a congressional charter. The Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering.
References:
National Academy of Sciences: Water Implications of Biofuels Production in the United States - October 10, 2007.
National Academy of Sciences: Water Implications of Biofuels Production in the United States: Report Brief [*.pdf] - October 10, 2007.
National Academy of Sciences: Increase in Ethanol Production From Corn Could Significantly Impact Water Quality and Availability if New Practices and Techniques Are Not Employed - October 10, 2007.
Article continues
posted by Biopact team at 7:06 PM 1 comments links to this post