As this blog previously has noted, in some parts of the world, where coal is an important fuel for heat and power, there is experimentation with solid biomass as a replacement for coal. Since GHG emissions, principally CO2, from the burning of coal is destructive to the climate, even supplementing with biomass is seen as a positive step.
The Biopact team has reported that solid biomass facilities will be installed in China. China Holdings previously had executed a contract for a 100 MW co-generation plant. “China Holdings executed its second development contract to build a 50MW biomass co-generation plant through its subsidiary China Power, Inc. The contract was signed with the local government of Anhui Province in the east of the country.”
Last fall China Power had acquired all the resources needed to construct and operate the plant. The system burns the biomass in two stages: first it partially burns it with air or oxygen and steam to make a “Syngas” containing combustible CO and H2, scrubs pollutants out of the synthetic gas, then burns the clean Syngas.
The Biopact team reported an advantage of the two stage processing is that it burns the biomass under a controlled processing temperature eliminating the “slagging” of residual ash, something that can occur with single stage, higher temperature gasification. As previously noted, the two-step process with a medium intermediate temperature (used by Choren, Värnamo/Chrisgas and others) enables more optimization. While it allows for intermediate gas cleaning, the two-step process also has its downsides (soot/coking).
The Biopact team describes the bio-energy process in 12 steps from collection, to combustion, to the production of electricity:
- The biomass fuel is collected in site and packed as bales. Biomass fuels are corn stalk, rice straw, cotton stalk, branches and other biomass by-products and waste material.
- The feedstock is then stored in the storage yard and delivered to the biomass power plant.
- Next, the biomass fuel is weighed and taken to the storage area.
- The feedstock is then taken by the pre-loading system from the storage area to the loading hopper.
- The hydraulic charging ram puts the biomass fuel from the loading hopper to the gasification chamber, where the biomass fuel is dried, heated, pyrolysed and partially oxidized. This releases moisture, combustible gas and volatile components.
- The residual ash is discharged from the gasification chamber by the ash removal system.
- The collected ash is taken for further processing into fertilizer or other products.
- The combustible gas and volatile components is then transferred to the combustion chamber where it is further oxidized and releases energy.
- The energy released during this process heats the water/steam in the boiler to produce superheated steam.
- The superheated steam drives the steam turbine and generator producing electricity.
- The electricity is delivered into the power grid through a substation.
- The gas flows into the emission control system that includes a spray tower, bag filters, exhaust fans, and stack. The gas is treated to remove acid gas and particles to meet environmental requirements.
The by-products from the process: the heat energy and ash, can be utilized to supply heat for households and industry, and fertilizer, thereby eliminating the need for the production of these products in an environmentally harmful manner.
Note: Use of the term “fertilizer” is perhaps, incorrect usage. Burying the char is a soil enhancement, commonly referred to as agri-char. It is unclear how much use of such soil enhancement has been adopted to Chinese agricultural practices.
Biopact References:
Biopact: China unveils $265 billion renewable energy plan, aims for 15% renewables by 2020 – September 06, 2007
Biopact: Expert: China’s biomass power plants to be profitable in three years – October 30, 2007
Biopact: A closer look at China’s biomass power plants – April 19, 2007
Biopact: China’s Dragon Power to raise US$2 billion for 100 biomass power plants – August 07, 2007
Biopact: China EnerSave retrofits coal plants to burn biomass – June 18, 2007
See also
“Recent Progress with Larger-Scale Biomass Gasification Systems (PDF)” Don J. Stevens, Aug. 2001
SELECTED RESEARCH PAPERS AND PUBLICATIONS in Advanced Fuel Research Consulting Brochure (PDF)
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The Biopact team provides advanced notice of the Second International Biochar Conference at the Newcastle Civic Centre, Newcastle, UK, September 8 to 10, 2008.
To explore carbon-negative bioenergy and biofuels
The conference will feature the results of the latest scientific research on biochar, and developments in policy and education. Producers of pyrolysis technology will be providing information on their units and organisations and individuals will be presenting case studies of the use of biochar in different agricultural systems.
Biochar in soils has been shown to:
The Australian via the Big Gav relays information from a WSJ article, which sounds a warning about the rise in Chinese coal consumption, and that of other countries, as well. As energy demand grows, countries turn to the cheapest and dirtiest energy source available. Anthropogenic emissions from coal-generated electric power already are contributing to potentially catastrophic climate change. To increase, rather than drastically reduce GHG emissions from coal is certainly a recipe for greater, more rapid destruction of life as we know it on the planet.
In discussing such matters with my spouse, I have used the low flying jet analogy. Yes, she asked, “the What?”, too. What I have heard said about flying a jet at high speed and at a low altitude is that you are dead and never know that you made a mistake.
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