Energy crops may soak up methane water
Quicknote bioenergy technology
Earlier we reported about several studies, tests and projects dealing with the bioremediation of brownfields and mining sites using biofuel crops. Such energy crops can be planted on polluted sites to prevent erosion, remove pollutants from the soil, stop the spread of small toxic particles through the air and to clean up ground water. After having done their work, the crops can be harvested and used as a feedstock for biofuels.
Now a company in northern Wyoming is conducting tests to see if growing hybrid poplar trees might be a good way to use water produced from coal-bed methane wells. The study of the process known as "phytoremediation" is being conducted by water resource management group CBM Associates and methane producer Windsor Energy Group.
The extraction of coal-bed methane or coalbed gas consists of drilling a steel-encased hole into a coal seam (200 - 1500 meters below ground). As the pressure within the coal seam declines, due to the hole to the surface or the pumping of small amounts of water from the coalbed, both gas and 'produced water' escape to the surface through tubes. Then the gas is sent to a compressor station and into natural gas pipelines. The 'produced water' is most often released into streams or pumped back into the ground. This 'methane water' typically contains sodium bicarbonate and chloride and if left untreated, it pollutes ground water.
Phytoremediation is the removal of pollutants by the use of engineered tree systems. The hybrid poplars were selected because they absorb large amounts of water relative to their growth. One acre of trees will use 1 million to 1.5 million gallons of water per year, according to environmental engineer and project manager Chris Ewert.
Ewert said he has seen hybrid poplars planted on top of covered landfills because they soak up a lot of water and don't let it become groundwater that could become polluted. "The trees use so much water, so I figured why not?" Ewert said in proposing the study. In April about 3,000 poplars were planted in a three-acre site. Methane well water is irrigating the trees through a gravity-fed sprinkler system from a reservoir. Ewert said the trees will be monitored the rest of the summer. Some have already grown 2 feet since they were planted.
"Some can grow six to eight feet in one year," Windsor environmental specialist Patsy Ballek said. The study will continue for 10 years, Ballek said. If the study is successful, Ewert said, the trees could be planted in tree belts near coal-bed methane well water reservoirs to give producers another means of using the water. Water is pumped to the surface by wells in order to recover the methane. "The water will be used by the trees and not go in the ground," Ewert said. As the study continues, Ewert said planting the trees on a larger scale will be analyzed for cost-effectiveness. "It definitely could prove to be viable," Ewert said.
Hybrid poplars are known to be fast growing trees and are proposed as energy crops in fast rotation cropping systems. They yield up to 35 metric tonnes of dry matter per year, and are considered to be excellent carbon sinks.
[entry ends here].
biomass :: bioenergy :: biofuels :: energy :: sustainability :: phytoremediation :: hybrid poplar :: methane
Article continues
Earlier we reported about several studies, tests and projects dealing with the bioremediation of brownfields and mining sites using biofuel crops. Such energy crops can be planted on polluted sites to prevent erosion, remove pollutants from the soil, stop the spread of small toxic particles through the air and to clean up ground water. After having done their work, the crops can be harvested and used as a feedstock for biofuels.
Now a company in northern Wyoming is conducting tests to see if growing hybrid poplar trees might be a good way to use water produced from coal-bed methane wells. The study of the process known as "phytoremediation" is being conducted by water resource management group CBM Associates and methane producer Windsor Energy Group.
The extraction of coal-bed methane or coalbed gas consists of drilling a steel-encased hole into a coal seam (200 - 1500 meters below ground). As the pressure within the coal seam declines, due to the hole to the surface or the pumping of small amounts of water from the coalbed, both gas and 'produced water' escape to the surface through tubes. Then the gas is sent to a compressor station and into natural gas pipelines. The 'produced water' is most often released into streams or pumped back into the ground. This 'methane water' typically contains sodium bicarbonate and chloride and if left untreated, it pollutes ground water.
Phytoremediation is the removal of pollutants by the use of engineered tree systems. The hybrid poplars were selected because they absorb large amounts of water relative to their growth. One acre of trees will use 1 million to 1.5 million gallons of water per year, according to environmental engineer and project manager Chris Ewert.
Ewert said he has seen hybrid poplars planted on top of covered landfills because they soak up a lot of water and don't let it become groundwater that could become polluted. "The trees use so much water, so I figured why not?" Ewert said in proposing the study. In April about 3,000 poplars were planted in a three-acre site. Methane well water is irrigating the trees through a gravity-fed sprinkler system from a reservoir. Ewert said the trees will be monitored the rest of the summer. Some have already grown 2 feet since they were planted.
"Some can grow six to eight feet in one year," Windsor environmental specialist Patsy Ballek said. The study will continue for 10 years, Ballek said. If the study is successful, Ewert said, the trees could be planted in tree belts near coal-bed methane well water reservoirs to give producers another means of using the water. Water is pumped to the surface by wells in order to recover the methane. "The water will be used by the trees and not go in the ground," Ewert said. As the study continues, Ewert said planting the trees on a larger scale will be analyzed for cost-effectiveness. "It definitely could prove to be viable," Ewert said.
Hybrid poplars are known to be fast growing trees and are proposed as energy crops in fast rotation cropping systems. They yield up to 35 metric tonnes of dry matter per year, and are considered to be excellent carbon sinks.
[entry ends here].
biomass :: bioenergy :: biofuels :: energy :: sustainability :: phytoremediation :: hybrid poplar :: methane
Article continues
Tuesday, August 15, 2006
Unlocking the vast energy potential of rice husks
Rice is the world's most important staple food, used by more than three billion people around the globe. The crop's production has doubled over the past 40 years and demand keeps growing. Now the Fraunhofer Institute - Europe's leading applied technology institute - has developed a highly efficient circulating fluidized bed combustion system that unlocks the energy potential contained in rice residues. Researchers from the institute's department of industrial automatisation are collaborating with scientists from the Hanoi University of Technology to test the system on a large and continuous scale after first tests in Magdeburg proved to be successful. For rice producing countries, the bioenergy potential from husks is considerable.
After paddy rice is processed, a large amount of biomass with a relatively high energy content (18 Gj/ton - higher heating value) is left over in the form of rice husks. According to the IEA's Bioenergy Task 33 on thermal biomass gasification, for each ton of processed rice, roughly 280kg of husks are left over, worth around 120 kWh[*.pdf]. Now consider that the world's total rice production in 2005 was 618 million tons (FAOStat), then it is not difficult to see the energy potential (if all this biomass were used in efficient gasification or combustion systems, it would yield roughly 266 Petajoules or 74 TWh of energy, which comes down to around 43.5 million barrels of oil - renewable energy from a waste stream).
For a country like Vietnam, which produced 36 million tons of rice in 2005 (FAOstat), such biomass combustion systems would mean a boost to its energy portfolio. That is why the collaboration with the Fraunhofer Institute is considered to be invaluable and has been sped up, since demand for energy in Vietnam is growing rapidly and high fossil fuel prices have become a real burden. Vietnam produces enough rice residues to provide 4.3 TWh of electricity, enough to satisfy the energy needs of around 1 million people for an entire year (for per capita energy consumption statistics, please visit the World Resources Institute's Earth Trends database).
Fraunhofer's 'circulating fluidized bed combustor' suspends the solid biofuel on upward-blowing jets of circulating air during the combustion process. The result is a turbulent mixing of gas and solids. The tumbling and circulating action, much like a bubbling fluid, provides more effective chemical reactions and heat transfer. The combustor reduces the amount of sulfur emitted in the form of SOx emissions as well as NOx. Fraunhofer's approach has been to study the exact combustion behavior of rice husks as they travel through the system. The combustor was then custom-designed to match those qualities. Dr.-Ing. Lutz Hoyer, project leader, explains the rationale behind the development of this system specifically for rice husks:
:: biomass :: bioenergy :: biofuels :: energy :: sustainability :: rice :: residues :: Vietnam ::
"These studies are very relevant to the market in Vietnam. Our aim is to deliver a competitive technology that can beat fossil fuels. Moreover, the environmental burden of burning fossil fuels is reduced with this biomass system that has universal appeal". His counterpart at Hanoi University of Technology, Dr. Pham Hoang Luong, adds: "Our university is currently investing in research and development. Fluidized bed combustion of biomass is one area where our future engineers will work on. Our collaboration with Fraunhofer is therefor much needed and appreciated."
After more tests in Magdeburg, Germany, the combustor will be transferred to Hanoi University in october to perform full-scale, long-term trials.
More information:
Fraunhofer: - Strom aus Reisschalen: Wissenschaftler aus Magdeburg und Hanoi erforschen Energiegewinnung aus Biomasse
Déchets: Les grains de riz, bientôt producteurs d'énergie? (August 14, 2006)
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posted by Biopact team at 2:24 PM 0 comments links to this post