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Biofuel

WHEN IT COMES TO OIL…GROW YOUR OWN (BIODIESEL FROM ALGAE)

Algae may be the breakthrough feedstock for the production of biodiesel in Hawaii, with the potential to greatly out-produce crops like oil palm, jatropha and sunflowers.  Algae has several other huge benefits compared to other potential feedstock crops.  Highly efficient, fast growing and not dependent on prime ag land or freshwater resources, algae could become a major source of power for everything from diesel buses and trucks to power plants,

Algae production removes CO2 from industrial emissions, utilizes non-potable water and doesn't compete for conventional agricultural land.

Algae can out-produce the nearest conventional crop by over one thousand percent.

Biodiesel can be blended with petro-diesel, or run 100% pure in conventional diesel engines with little or no modifications. So, transitioning to locally produced biodiesel will be a relatively seamless process.

Algae thrives on CO2, so piping the gas from large emmitters like coal fired powerplants and refinery operations solves two problems at once.

Algae doesn’t compete with food-producing crops, one of the biggest points of contention with biofuels in general. It requires only brackish water, or even wastewater from treatment facilities. Prime agricultural land will not be used for algae production, as it doesn’t require soil at all and grows in shallow ponds that can be placed anywhere.

One of the byproducts of the algae to oil conversion process is residual biomass rich in protein. This material is useful for cattle feed and can be pelletized for use with fish farms.

During the oil crisis in the 1980’s the Federal government pumped considerable research money into the Aquatic Species Program.  It helped to identify and classify algae that could be useful in producing oil.  Much of this early research now resides at the University of Hawaii, so it is not a coincidence that Hawaii is, once again,  at the forefront of algae research and developmemt.  Hawaii also has a very stable temperature range, a key component for successfully scaling up production.

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HOW BIOMASS  GASIFICATION WORKS

It is thermo-chemical conversion of solid biomass into a combustible gas mixture (producer gas) through a partial combustion route with air supply restricted to less than that theoretically required for full combustion. The newest method for generating electricity is gasification. This method captures 65-70% of the energy present in solid fuels by converting it first to combustible gases. These gases are then burnt as we currently burn natural gas, and create energy.

Composition of Producer gas :

Carbon monoxide             – 18%-20%

Hydrogen                         – 15%-20%

Methane                           – 1%-5%

Carbon Dioxide                 – 9%-12%

Nitrogen                          – 45%-55%

Calorific value                   – 1000 – 1200 kcal/m3

Why gasify biomass ?

Ø Producer gas can be used as a fuel in place of diesel in suitably designed/adopted internal combustion (IC) engines coupled with generators for electricity generation.

Ø Producer gas can replace conventional forms of energy such as oil in may heating applications in the industry.

Ø The gasification process renders use of biomass relatively clean and acceptable in environmental terms.

Ø Large monetary savings can accrue through even partial substitution of diesel in existing diesel generator (DG) sets.

What type of biomass can be gasified?

Most commonly available gasifiers use wood/woody biomasses; some can use rice husk as well.  Many other non-woody biomass materials can also be gasified, although gasifiers have to be specially designed to suit these materials and the biomass may have to be compacted in many cases.

How do gasifiers work?

Gasifiers can be of ‘updraft’ or ‘downdraft’ types.  The working of biomass gasification system can be explained by considering a  typical downdraft gasifier.  In this type of gasifier, fuel and air move in a co-current manner.  In updraft gasifiers, on the other hand, fuel and air move in counter-current manner.   However, the basic reaction zones remain the same.

Fuel is loaded into the reactor from the top.   As the fuel moves down, it is subjected to drying and pyrolysis.  Air is injected into the reactor in the oxidation zone, and through the partial combustion of pyrolysis products and solid biomass, the temperature rises to 1100 oC.  This helps in breaking down heavier hydrocarbons and tars.   As these products move downwards, they enter the reduction zone where producer gas is formed by the action of carbon dioxide and water vapour on red-hot charcoal.   The hot and dirty gas is passed through a system of coolers, cleaners, and filters before it is sent to engines.

RELATED STORIES:

Green Car of the Years Tours California on Synthetic Fuel

Algae for Biofuels: Moving from Promise to Reality…But, How Fast?

Jatropha: A Promising Source of Biodiesel Feedstock

HECO Signs with Aina Koa Pono for 16 Million Gallons of Local Biofuel per Year

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