Sludge Watch ==> Sludges - The Power of Biomass - Biofuels

[Maureen Reilly]

The Irish Independent

The power of biomass
June 12 2007

BIOENERGY is a locally available energy source with the highest versatility 
among the renewable energies. It can be made available in solid, liquid or 
gaseous forms. This article aims to shed some light and understanding on 
some of key terminologies and potential uses of biomass.



What is biomass?


Biomass comprises organic matter originally derived from plants as a result 
of the photosynthetic conversion process, or from animals. It is stored as 
chemical energy to provide heat, electricity or transport fuels.


Biomass resources include wood from forests, residues from agricultural or 
forestry production and organic waste by-products from the food and fibre 
industries.


The chemical energy contained in the biomass is derived from solar energy 
through plant growth. Photosynthesis is the mechanism in which plants 
manufacture food by taking in the solar energy from the sun to convert water 
and carbon dioxide to starches, sugars, cellulose, lignin etc.


What is bioenergy?


A number of conversion routes exist to change biomass into useful forms of 
energy, such as gasification, direct combustion, pyrolisis etc. They are 
used to convert the biomass into a useful bioenergy project to produce 
either heat, electricity or transport fuel.


Biomass fuels vary with the plant species, the nature of the resource 
material (such as straw, wood, bark, leaves, sludge, manure etc), and the 
moisture content.


Energy terminology


The basic energy value of biomass is measured as joules of energy in 1g of 
fuel (J/g). One joule is a very small quantity of energy -- one chocolate 
bar contains about 1m joules of energy. The kilowatt hour (kWh) is perhaps a 
more convenient unit of energy for the renewable energy sector, for two 
reasons. Firstly, the kWh is a larger unit of energy than the joule -- one 
kWh equals 3,600,000 joules. Secondly, the definition of the kWh is linked 
to the operation of energy consuming or energy producing appliances.


For convenience, biomass energy values are normally quoted in Mega Joules 
per Kg (MJ/kg) or Giga Joules per tonne (GJ/t).


Weight


This is usually measured in kilograms (kg) for small amounts of biomass and 
tonnes (t) for larger, commercial scale amounts. Since biomass contains 
varying levels of water, it is important to specify the moisture content 
when quoting the weight of fuel. For easy comparison between fuels they are 
usually presented as the dry weight of biomass material that is at 0pc 
moisture content (m.c).


Willow generally has a moisture content of 50 - 55pc at harvest and 
miscanthus is normally in the region of 20pc at harvest. As a rule of thumb, 
a green tonne of woody biomass will contain approximately one third of the 
energy contained in one tonne of bituminous coal.


Volume


The usual metric unit used for volume is cubic metres (m³). When individual 
pieces of biomass are collected together there is always a considerable 
voidage (volume of air in the spaces between the separate pieces of wood. 
This makes the simple unit of volume of limited practical use other than to 
calculate storage requirements for the biomass.


For biomass, its density is sensitive to moisture content, and since biomass 
varies widely in moisture content as well as in material composition it is 
more difficult to define. The fundamental measure for biomass is basic 
density. Taking wood as an example, this is the weight of oven dry wood 
contained in a unit volume of green wood in kg/m³. Basic density = oven-dry 
mass/volume at 50pc moisture.


Densification (Pellets)


Biomass in the form of small particles such as sawdust or shavings can be 
densified to increase the density and allow easier handling or storage. The 
bulk density changes with the degree of compaction.


Smaller briquettes or pellets can be made from sawdust and chips, and can 
vary from 600 kg/m³to 1,500 kg/m³ basic density, depending on the equipment 
used for densifying the material and the biomass type. Moisture content of 
the compacted material usually needs to be between 7pc and 14pc m.c. If 
higher it will not compact easily, as water does not compress, and if lower 
the compacted product will not bind as well.
http://www.independent.ie/farming/the-power-of-biomass-701088.html


.....................................................


June 12, 2007 Toolbox

California researchers plan to make biofuels in a novel way that doesn’t 
involve food crops or microbial fermentation.
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A new research effort involving three University of California campuses and 
West Biofuels LLC, will develop a prototype research reactor that will use 
steam, sand and catalysts to efficiently convert forest, urban, and 
agricultural “cellulosic” wastes that would otherwise go to landfills into 
alcohol that can be used as a gasoline additive.

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Learn more ... “We have a very feasible design to combine individual 
components of technology that have been proven separately into a successful 
biomass processing prototype,” said Robert Cattolica, leader of the research 
program and a professor of mechanical and aerospace engineering at UC San 
Diego’s Jacobs School of Engineering. Cattolica is the principal 
investigator of the project, which includes researchers at UC San Diego, 
Davis, and Berkeley.

Since carbon dioxide is naturally recycled from the atmosphere into 
cellulose in plants and back into the atmosphere as carbon dioxide when 
plants decompose, burning biomass-derived fuel such as alcohol in internal 
combustion engines has a zero net effect on the amount of carbon dioxide in 
the atmosphere. On the other hand, burning fossil fuels continually adds 
carbon dioxide, a greenhouse gas, to the atmosphere.

The new biofuels research project was inspired by California’s Global 
Warming Solutions Act, which was signed into law by Governor Arnold 
Schwarzenegger in September 2006. The act requires a 25 percent reduction in 
greenhouse gas emissions in California by 2025. Substituting biomass fuel 
for petroleum would help California achieve its goal. The two-year UC 
project is funded with a $1.85 million grant from West Biofuels LLC, a San 
Rafael, CA, company that is developing the biomass-to-alcohol technology, 
and a $1.15 million state-funded UC Discovery Grant.

“My company is excited about partnering with the University of California on 
a very promising technology that could eventually have a significant 
beneficial impact on our environment while also reducing California's 
reliance on oil imports,” said Peter Paul, chief executive officer of West 
Biofuels.

The alcohol currently added to gasoline sold in California is derived from 
corn, sugar cane, beets, or other farm crops. About 95 percent of the 
alcohol additive comes from outside of California and as far away as China. 
Rather than fermenting food crops into ethanol, Cattolica’s project will use 
a thermo chemical process to break down shredded cellulosic wastes into a 
mixed alcohol, predominately ethanol. “The technology we’re developing will 
tap a huge, energy-rich resource that now is literally going to waste,” said 
Cattolica.

The prototype reactor will mix the wastes with high temperature sand in a 
reaction chamber while the mixture is heated with steam. The gasification 
process generates an energy rich combination of hydrogen (H2), carbon 
monoxide (CO), methane (CH4), and carbon dioxide (CO2). Those gases will be 
catalytically “reformed” into alcohols. About 30 percent of the energy 
content of the starting material will be burned to supply the energy needed 
to operate the plant.

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This will actually include a three-step process. First, the biomass will be 
gasified thermochemically in a process that is widely used around the world 
to process wood, coal, and other carbon-containing materials into a 
“producer gas.” The methane in producer gas is typically burned to power 
electricity-generating power plants. However, the new reactor will 
catalytically “reform” the producer it into syngas, a mixture of hydrogen 
gas and carbon monoxide. In the final step, the syngas will be catalytically 
converted into mixed alcohols with a “synthesis” catalyst similar to one 
developed in the late 1980s by Dow Chemical Company.

In order for all the processes to run at maximum efficiently, the 
researchers will make use of highly sensitive laser sensors developed at 
UCSD to continuously monitor the entire operation. Process-control 
algorithms under development at UCSD’s Center for Control Systems and 
Dynamics (CCSD) will use the sensor data to continuously fine-tune steam 
temperatures and flows, gas mixtures, and catalyst regeneration to achieve 
the most efficient and reliable conversion of the biomass into fuel.

Cattolica’s team, which includes nine UC professors and seven post-doctoral 
fellows, will conduct research on a $1 million, 4-ton-per-day reactor. West 
Biofuels is building the reactor and will donate it to the University of 
California. Lessons learned will be incorporated into a 100-ton-per-day 
pilot plant, which could generate one 10,000-gallon tanker truck of 
mixed-alcohol fuel for every seven semi-tractor trailer trucks of biomass 
waste. California generates a huge volume of such wastes.

The Orange County basin alone produces about 30,000 tons of urban green 
wastes per day, which is simply dumped at landfills and used as compost. 
Cattolica said that waste supply could generate 3 million gallons per day of 
mixed-alcohol fuel, which is equivalent to all the ethanol currently added 
to California gasoline.

The biomass processing technology could also permit California to reduce its 
dependence on outside sources of ethanol. Motorists in California currently 
purchase more than 900 million gallons of ethanol a year, or 25 percent of 
the national total. However, the state produces only about 5 percent of the 
ethanol fuel it consumes. Schwarzengger issued an executive order in 2006 
that requires the state to produce at least 20 percent of its biofuels by 
2010, 40 percent by 2020, and 75 percent by 2050.

Cattolica said green wastes generated in San Diego and the Los Angeles and 
San Francisco Bay areas represent a huge untapped energy resource.

“The more paper and cardboard, agricultural and forest wastes, and sludge 
and municipal solid waste that we can process into biofuels the sooner the 
state can meet the state’s biofuels goals,” said Cattolica. “This is all 
attainable, and it will allow us to continue using internal combustion 
engines, reduce our dependence on fossil fuels, and reduce the production of 
greenhouse gases.”

Source: University of California - San Diego
http://www.physorg.com/news100838926.html