|
Biomass
Wastes |
||||
|
||||
|
|
|
|||
|
|
||||
Biomass
is the material derived from plants that use sunlight to grow which include
plant and animal material such as wood from forests, material left over from
agricultural and forestry processes, and organic industrial, human and animal
wastes. Biomass comes from a variety of sources which include:
The
energy contained in biomass originally came from the sun. Through
photosynthesis carbon dioxide in the air is transformed into other carbon
containing molecules (e.g., sugars, starches and cellulose) in plants. The
chemical energy that is stored in plants and animals (animals eat plants or
other animals) or in their waste is called bio-energy. When
biomass is burned it releases its energy, generally in the form of heat. The
biomass carbon reacts with oxygen in the air to form carbon dioxide. If fully
combusted, the amount of carbon dioxide produced is equal to the amount which
was absorbed from the air while the plant was growing. In
nature, if biomass is left lying around on the ground it will break down over
a long period of time, releasing carbon dioxide and its store of energy
slowly. By burning biomass its store of energy is released quickly and often
in a useful way. So converting biomass into useful energy imitates the natural
processes but at a faster rate. Biomass
wastes can be transformed into clean energy and/or fuels by a variety of
technologies, ranging from conventional combustion process to state-of-the
art thermal depolymerization technology. Besides
recovery of substantial energy, these technologies can lead to a substantial
reduction in the overall waste quantities requiring final disposal, which can
be better managed for safe disposal in a controlled manner while meeting the
pollution control standards. Biomass
waste-to-energy conversion reduces greenhouse gas emissions in two ways. Heat
and electrical energy is generated which reduces the dependence on power
plants based on fossil fuels. The greenhouse gas emissions are significantly
reduced by preventing methane emissions from landfills. Moreover,
waste-to-energy plants are highly efficient in harnessing the untapped
sources of energy from wastes. Conversion
Technologies Biomass
energy technology is inherently flexible. The variety of technological
options available means that it can be applied at a small, localized scale
primarily for heat, or it can be used in much larger base-load power
generation capacity while also producing heat. Biomass generation can thus be
tailored to rural or urban environments, and utilized in domestic, commercial
or industrial applications. A host
of technologies are available for realizing the potential of biomass waste as
an energy source, ranging from very simple systems for disposing of dry waste
to more complex technologies capable of dealing with large amounts of
industrial waste. Biomass
can be converted into energy by simple combustion, by co-firing with other
fuels or through some intermediate process such as gasification. The energy
produced can be electrical power, heat or both (combined heat and power, or
CHP). The advantage of utilizing heat as well as or instead of electrical
power is the marked improvement of conversion efficiency -- electrical
generation has a typical efficiency of around 30 percent, but if heat is used
efficiencies can rise to more than 85 percent. Biochemical
processes, like anaerobic digestion, can also produce clean energy in the
form of biogas which can be converted to power and heat using a gas engine.
In addition, wastes can also yield liquid fuels, such as cellulosic ethanol,
which can be used to replace petroleum-based fuels. Algal biomass is also
emerging as a good source of energy because it can serve as natural source of
oil, which conventional refineries can transform into jet fuel or diesel
fuel. Major
Types of Biomass Waste Biomass
energy projects provide major business opportunities, environmental benefits,
and rural development. Feedstocks can be obtained
from a wide array of sources without jeopardizing the food and feed supply,
forests, and biodiversity in the world. Agricultural
residues -- Crop residues
encompasses all agricultural wastes such as bagasse,
straw, stem, stalk, leaves, husk, shell, peel, pulp, stubble, etc. Large
quantities of crop residues are produced annually worldwide, and are vastly
underutilized. Rice produces both straw and rice husks at the processing
plant which can be conveniently and easily converted into energy. Significant
quantities of biomass remain in the fields in the form of cob when maize is
harvested which can be converted into energy. Sugar cane harvesting leads to
harvest residues in the fields while processing produces fibrous bagasse, both of which are good sources of energy.
Harvesting and processing of coconuts produces quantities of shell and fiber
that can be utilized. Current
farming practice is usually to plough these residues back into the soil, or
they are burnt, left to decompose, or grazed by cattle. These residues could
be processed into liquid fuels or thermochemical
processed to produce electricity and heat. Agricultural residues are
characterized by seasonal availability and have characteristics that differ
from other solid fuels such as wood, charcoal, char briquette. The main
differences are the high content of volatile matter and lower density and
burning time. Animal
waste -- There are a wide
range of animal wastes that can be used as sources of biomass energy. The
most common sources are animal and poultry manures. In the past this waste
was recovered and sold as a fertilizer or simply spread onto agricultural
land, but the introduction of tighter environmental controls on odor and
water pollution means that some form of waste management is now required,
which provides further incentives for waste-to-energy conversion. The
most attractive method of converting these waste materials to useful form is
anaerobic digestion which gives biogas that can be used as a fuel for
internal combustion engines, to generate electricity from small gas turbines,
burnt directly for cooking, or for space and water heating. Forestry
residues -- Forestry residues are
generated by operations such as thinning of plantations, clearing for logging
roads, extracting stem-wood for pulp and timber, and natural attrition.
Harvesting may occur as thinning in young stands, or cutting in older stands
for timber or pulp that also yields tops and branches usable for biomass
energy. Harvesting operations usually remove only 25 to 50 percent of the
volume, leaving the residues available as biomass for energy. Stands
damaged by insects, disease or fire are additional sources of biomass. Wood
wastes -- Wood processing
industries primarily include sawmilling, plywood, wood panel, furniture,
building component, flooring, particle board, moulding,
jointing and craft industries. Wood wastes generally are concentrated at the
processing factories, e.g., plywood mills and sawmills. The amount of waste
generated from wood processing industries varies from one type industry to
another depending on the form of raw material and finished product. Generally,
the waste from wood industries such as saw millings and plywood, veneer and
others are sawdust, off-cuts, trims and shavings. Sawdust arise from cutting,
sizing, re-sawing, edging, while trims and shaving are the consequence of
trimming and smoothing of wood. In general, processing of 1,000 kg of wood in
the furniture industries will lead to waste generation of almost half (45
percent), i.e., 450 kg of wood. Similarly, when processing 1,000 kg of wood
in sawmill, the waste will amount to more than half (52 percent), i.e., 520
kg wood. Industrial
wastes -- The food industry
produces a large number of residues and by-products that can be used as
biomass energy sources. These waste materials are generated from all sectors
of the food industry with everything from meat production to confectionery
producing waste that can be utilised as an energy
source. Solid
wastes include peelings and scraps from fruit and vegetables, food that does
not meet quality control standards, pulp and fibre
from sugar and starch extraction, filter sludges
and coffee grounds. These wastes are usually disposed of in landfill dumps. Liquid
wastes are generated by washing meat, fruit and vegetables, blanching fruit
and vegetables, pre-cooking meats, poultry and fish, cleaning and processing
operations as well as wine making. These
waste waters contain sugars, starches and other dissolved and solid organic
matter. The potential exists for these industrial wastes to be anaerobically digested to produce biogas, or fermented to
produce ethanol, and several commercial examples of waste-to-energy
conversion already exist. Pulp
and paper industry is considered to be one of the highly polluting industries
and consumes large amount of energy and water in various unit operations. The
wastewater discharged by this industry is highly heterogeneous as it contains
compounds from wood or other raw materials, processed chemicals as well as
compound formed during processing. Black liquor can be judiciously utilized
for production of biogas using anaerobic UASB technology. Municipal
solid wastes and sewage --
Millions of tons of household waste are collected each year with the vast
majority disposed of in open fields. The biomass resource in MSW comprises
the putrescibles, paper and plastic and averages 80
percent of the total MSW collected. Municipal solid waste can be converted
into energy by direct combustion, or by natural anaerobic digestion in the
engineered landfill. At the landfill sites the gas produced by the natural
decomposition of MSW (approximately 50 percent methane and 50 percent carbon
dioxide) is collected from the stored material and scrubbed and cleaned
before feeding into internal combustion engines or gas turbines to generate
heat and power. The organic fraction of MSW can be anaerobically
stabilized in a high-rate digester to obtain biogas for electricity or steam
generation. Sewage
is a source of biomass energy that is very similar to the other animal
wastes. Energy can be extracted from sewage using anaerobic digestion to produce
biogas. The sewage sludge that remains can be incinerated or undergo pyrolysis to produce more biogas.The
growing use of waste-to-energy technologies as a method for safe disposal of
solid and liquid wastes, and as an attractive option to generate heat, power
and fuels, has greatly reduced environmental impacts of a wide array of
wastes. An environmentally sound and techno-economically viable methodology
to treat different classes of waste is highly crucial for the sustainability
of modern societies. A transition from conventional energy systems to one
based on renewable resources is necessary to meet the ever-increasing demand
for energy and to address environmental concerns. |
|||||||||||||
|
|
|||
|
|
|
|||
Do you agree or disagree with this
article? Send in
your own article.
Readers Comments
|
Date
|
Comment
|
|
Harry
Valentine |
Solid biomass
wastes can certainly be burned directly or by gasification to raise steam and
power steam engines. Enginion of Germany and Schoell Cyclone Power in the Much waste biomass
can be processed into combustible liquid fuel . . . using the waste heat from
existing thermal power stations to sustain the most energy intensive aspect
of ethanol production. |
|
Len
Gould |
I
agree with your "An environmentally sound and techno-economically viable
methodology to treat different classes of waste is highly crucial for the
sustainability of modern societies." -- HIOWEVER, I'm disappointed that
you've failed to address the issue of returning minerals from plant material
to the soil from where it originated. NO method of exploiting biomass should
be considered which does ot also take great care to
neither distribute as aerosol waste gas, or
contaminate; the phosphorous, potasium and trace
minerals required for plant growth contained in the bio-mass. That requiement basically rules out co-firing biomass,
especially with coal. Projects which highly centralize the materials are also
questionable unless they also include the cost of re-distributing clean ash
back to the source soils. Any
alternative is simply "mining the soils", a short-term strategy at
best. Also of
interest. Adding
those four (by far the four largest biomass crops produced) provides 649 Mmst. Assume stovers, straws,
other crops not counted could double that to 1,300 Mmst.
Also assume it requres 2 tons bio-mass to equal 1
ton coal in a boiler, eg 1060 tons coal = 2120 tons
biomass. 2,120 - 1,300 = 820 tons missing. So even
if we choose to not eat, feed cattle pigs and chickens, produce any paper or
lumber, we would still not be able to substitute present coal consumption
with bio-mass. Your
number may vary, but I believe this is in the ballpark. |
|
Richard Vesel |
A good
summary article! The new fact which I was unaware of before was how much
waste is generated by the processing of forestry products for wood and
furniture - about 50%. Pyrolizing
this waste creates two useful byproducts - pyrolitic
oil, which can be used as a liquid fuel to straight or mix with bunker oil
for ships and power plants, and a high-carbon char which can be burned with,
or as a substitute for, coal. NewEarth's eCoal is one such product. Generally, I see gasifiers as being among the best technologies for
dealing with all sorts of organic waste materials. This technology is carbon
neutral, recycling carbon originating in the biosphere, over and over again.
Large-scale gasifier projects need more visibility
and support so that they make faster inroads into our energy picture. Regards, RWVesel |
|
Len
Gould |
Start
building solar thermal NOW. Forget this bio-mass fization.
|
|
Ramanathan
Menon |
Dear Salman: A well-studied,
in-depth and informative article. Biomass is an
important energy source contributing to more than 14% of the global energy
supply. About 38% of such energy is consumed in developing countries,
primarily in the rural and traditional sectors of the economy. Further, the
vast agricultural produce in The strong demand
for bio-fuel is in response not only to high crude petroleum prices, but also
to the growing concerns about global climate change. Two major bio-fuels for
the transportation sector, bio-ethanol and bio-diesel have gained worldwide
acceptance. In June 2007, the
oil giant Bharat Petroleum signed a US$ 160 million deal with British
bio-diesel producer D1 Oils, creating a JV, which will become the world’s
largest producer of Jatropha oil by 2011. Energy efficiency
provides a powerful and cost-effective mechanism to achieve a sustainable
energy future. Improvements in energy efficiency can reduce the need for
investment in energy infrastructure, cut fuel costs, increase competitiveness
and improve consumer welfare. Environmental benefits can also be achieved by
the reduction of greenhouse gases emissions. Energy security can also benefit
from improved energy efficiency by decreasing the reliance on imported fossil
fuels. The mission of the
Bureau of Energy Efficiency (BEE) in Energy efficiency
has proven to be a cost-effective strategy for building economies without
necessarily growing energy consumption. It offers a
solution to reduce demand while continuing to pursue the goals of economic
and environmental sustainability and provides opportunity to free up capital
for other social and economical development needs. Ramanathan
Menon |
|
Roger
Arnold |
Richard,
Pyrolizing this
waste creates two useful byproducts - pyrolitic
oil, which can be used as a liquid fuel to straight or mix with bunker oil
for ships and power plants, and a high-carbon char which can be burned with,
or as a substitute for, coal. NewEarth's eCoal is one such product. High
temperature flash pyrolysis, used to produce the
"liquified biomass" that you're talking
about, does not produce large amounts of char. As I understand it, the char
that it does produce is not especially rich in retained mineral
nutrients. It has a high content of graphite particles, and is not especially
effective as a soil ammendment. That destroys what
I consider to be its highest value, for carbon sequestration and improving
soil fertility. It can substitute for coal in power plants, but never
in anything approaching the quantities needed. Conversely,
the slow low temperature pyrolysis that produces
the best agricultural bio-char has a low yield of condensible
liquids and tars. Its main condensible liquids are
methanol and water (but with significant fractions of turpenes
and god knows what else), and its main gaseous products are hydrogen, carbon
monoxide and carbon dioxide, with traces of methane. Len, Start
building solar thermal NOW. Forget this bio-mass fization.
Solar
thermal is fine, but bio-mass has a solid place as well. It's storable, and
in conjunction with CAES, can provide the short-reaction dispatchable
power needed to back wind and solar energy. And bio-char is great for
improving soil quality while sequestering carbon. |
|
Peter Boisen |
Good article.
Agree with Len Gould that it is important to consider the return of nutrients
to the soil, thus forming a closed loop system, and avoiding eutrophication problems. One of the most
challenging waste problems is the handling of MSW (municipal solid waste).
Although far from being the most significant source of renewable biomass
resources it presents a number of challenges. http://www.avfallsverige.se/m4n?oid=U2009:05
At this web site you can download an English language study prepared in 2008,
but issued in May, 2009, concerning European disposal of MSW. The report was
prepared by PROFU for Avfall Sverige
and provides very interesting information, also listing by country all
existing regulations and incentives. A really interested reader will find
lots of useful references in this report. http://www.cmslegal.com/Documents/Cleantech_Report_June2009.pdf
Another useful report isssued last month which
highlights new possibilities within the renewables
sector. |
|
Joel
Keller |
We
have integrated a front-end recycling facility with a back-end pyrolysis to energy technology using specially
hardened internal combustion engines driving generator sets. Our process
takes single stream MSW and through automated Materials Recycling Facility
(MRF) equipment, sorts out 60%+ of the input volume in the form of ferrous
metals, aluminum, glass and paper/cardboard. These are sold off to the
market. The residues of non-recyclable plastics, food wastes, some cellulosic
material and wood are shredded and used as engineered fuel or RDF by a third
generation slow pyrolysis system, which produces
high BTU syngas consisting mostly of methane,
ethane, propane, butane, CO and Hydrogen. The gas stream is scrubbed to
eliminate particulates and oil condensates, which are diverted and stored.
The gas is then used to fire a specially modified internal combustion engine
to drive a generator. The hot exhaust gas is used to maintain the pyrolysis system's operating temperature. We have
customers for the oil, the char and the power. We charge a "tipping
fee" for receiving the MSW. We sell the recyclables. The process
qualifies for "Renewable Energy Certificates" under most RPS
mandates. Providing that projects are begun no later than the end of 2010,
they each qualify for the 30% Federal Grant in Lieu of the ITC for renewable
energy projects. And, if they are sited appropriately, they will also qualify
for New Markets Tax Credit monetization. With
some 7 or 8 income streams, cashflow is positive
from startup and the ROI for the project is very high. www.randaenergysolutions.com
|
|
Douglas Trerice |
Great article
and comments! Sooo, why does biomass still have a
back seat to wind/solar? |
|
Rinaldo Sorgenti |
Very
interesting article indeed. About Len Gould comment: "...Projects which
highly centralize the materials are also questionable unless they also
include the cost of re-distributing clean ash back to the source soils."
Yes, it is logically important to return/re-distributing clean ash back to
the soil. Which is the problem there ? On the
contrary, properly re-distributing this clean ash back to the soil, in a
controlled proportion to the soil quality, might help a lot in overcoming
various other soil's problems (i.e., improving the capacity of water retention
and improving the soil production for many crops). But a further question come to my mind. It relates to the
sentence written at the top of the article: "If fully combusted, the
amount of carbon dioxide produced is equal to the amount which was absorbed
from the air while the plant was growing.".
O.K. but, considering that the energy derived from burning the biomass is
significantly lower than burning fossil fuels, so the amount of carbon
dioxide is more than double for the same amount of electricity produced by
burning fossil fuels, which is the advantage in term of GHG total emissions
to the atmosphere? It
would not be better and wise to avoid burning this biomass for energy
production and instead burying it underground? Finally, nature took 20-30
years to capture and storage the CO2 insite plants
and instead of making use of this natural effort to reduce CO2 from the air,
we promote the return of same to the atmosphere as a replacement from other
fossil fuels (primarily coal) which give a much better energy return. Some
might object that, finally, burying the biomass will only delay the time when
such biomass constituents comes back to the
atmosphere anyway. Right, but we just need to look at the involved time
frame. A conventional coal power plant has an operational lifetime of about
30-40 years, after which it might be possible that science is able to
discover and put in place new forms of energy which do not originate the
claimed huge amount of GHG. In that time frame, there would be very little concern
about the direct return to the atmosphere of the biomass constituents
mentioned above. Finally,
we should not discriminate any form of conventional or new energy sources; we
need all of them, combined in an intelligent ratio, depending on place to
place, technologies availability, level of the economic developments, etc.
Even RES need to be considered without loosing sight of the cost-efficiency
ratio and this is the "natural" complement to the most intelligent
and diversified "Fuel Mix" of the most industrialised
countries, like The
better form of energy is intelligence, while speculations often indulge
towards climate change arguments and RES. A very different sort of
"science"! |
|
bill payne |
We're
concerned that more energy may be expended collecting biomass than is
produced by biomass. EROEI for different
forms of biomass? Albuquerque Journal
published Wednesday August 11, 2009 "[N]ow, Brown argues, those trends in growing population and
increasing energy use. are hurtling headlong toward
fundamental global limits. If we do not reduce our population growth and our
per capita energy consumption, we'll burn through the last of our fossil
fuels; triggering devastating climate change and, when the fuels run out,
societal collapse. ..." http://home.comcast.net/~bpayne37/whitman59/whitman59after.htm#jimbrown
|
Return to Environmental Update
Return to Homepage
Roubidoux
True tales of the Huckleberry Finn type adventures of a boy who journeys from
delinquency in California to Southern culture in the Missouri Ozarks. Although told
through the eyes of a twelve year old who never grows old, much of the real life
adventure is emotionally timeless with appeal to all ages. Brutally honest at
times but never off colored.
A sample from Roubidoux may be read here.
The book may be ordered here.
Do you know that your body is naturally acidic which makes you susceptible to all manner of unhealthy conditions and illnesses? By making your body alkaline instead of acidic you mitigate these potential health problems. One way of doing this is to drink alkaline water. The above machine is called the "Athena" and makes tap water into pure, clean alkaline water. It's rather expensive, but it's the best in the world. Isn't your health worth it? Click here to learn more and order it.
