Archive

Archive for the ‘Biomass Energy’ Category

Fermentation of Biomass

December 12, 2009 Leave a comment

Fermentation of biomass is process of generation of producer gas then producer gas to ethanol.

Following the gasification of biomass to producer gas, the gas is converted into liquid products (e.g., ethanol) via fermentation.

Biological means fermentation can be used to produce fluid biomass fuels. For example, methane gas is produced in China for local energy needs by anaerobic microbial digestion of human and animal wastes. Ethanol for automotive fuels is currently produced from starch biomass in a two-step process: starch is enzymatically hydrolyzed into glucose; then yeast is used to convert the glucose into ethanol. About 1.5 billion gallons of ethanol are produced from starch each year in the United States.

Fermentation of lignocellulosic biomass to ethanol and dimethyl ether is an attractive route to energy feedstock that supplements the depleting stores of fossil fuels.

Biomass is a carbon-neutral source of energy, since it comes from dead plants, which means that the combustion of ethanol produced from lignocelluloses will produce no net carbon dioxide in the earth’s atmosphere.

Also, biomass is readily available, and the fermentation of lignocelluloses provides an attractive way to dispose of many industrial and agricultural waste products. Finally, lignocellulosic biomass is a renewable resource. Many of the dedicated energy crops can provide high energy biomass, which may be harvested multiple times each year.

Biomass Digestion (Using Anaerobic Digestion)

December 11, 2009 Leave a comment

Anaerobic digestion (AD) is a natural process and is the microbiological conversion of organic matter to methane in the absence of oxygen. The decomposition is caused by natural bacterial action in various stages. It takes place in a variety of natural anaerobic environments, including water sediment, water-logged soils, natural hot springs, ocean thermal vents and the stomach of various animals (e.g. cows). The digested organic matter resulting from the anaerobic digestion process is usually called digestate.

Biomass Pyrolysis

December 10, 2009 Leave a comment

Pyrolysis is the chemical decomposition of condensed organic substances by heating. Pyrolysis is the basis of several methods that are being developed for producing fuel from biomass, which may include either crops grown for the purpose or biological waste products from other industries. Vehicles were run on gas produced by pyrolysis of wood in times of war to replace unavailable fossil fuels. The improved electrical efficiency of the energy conversion via pyrolysis naturally means that the potential reduction in CO2 is greater than with combustion. Pyrolysis of biomass generates three different energy products in different quantities: coke, gas and oils. Pyrolysis as a first stage in a two-stage gasification plant for straw and other agricultural materials does deserve consideration.

The following technologies have been proposed for biomass pyrolysis:

  • Fixed beds
  • Augers
  • Ablative Processes
  • Fluidized Bed

Biomass Combustion

December 9, 2009 Leave a comment

Biomass combustion simply means burning organic material. For millennia, humans have used this basic technology to create heat and, later, to generate power through steam. While wood is the most commonly used feedstock, a wide range of materials can be burned effectively.

These include residuals and byproducts such as straw, bark residuals, sawdust and shavings from sawmills, as well as so-called “energy crops” such as switch grass, poplar and willow that are grown specifically to create feedstock. Pelletized agricultural and wood residues are also an increasingly popular option because they are very easy to handle.

One recent technology advance is the introduction of pellet stoves, which use an electrically driven auger to deliver a steady supply of compressed pellets of wood or other biomass into the fire.

Biomass Gasification

November 19, 2009 Leave a comment

Biomass gasification is basically conversion of solid Biomass (Wood, agriculture residues etc.) in to a combustible gas mixture normally called “Producer Gas” (or low Btu gas). The process involves partial combustion of Biomass. Partial combustion is carried out in absence of air or less air than the stroichiometric requirement of air for complete combustion.

Partial combustion produces Carbon Monoxide (CO) as well as hydrogen (H2) which are both combustible gas. Solid Biomass fuels, which are usually inconvenient and have low efficiency of utilization can thus, be converted in to a high quality gaseous fuel with associated convenience etc. In Indian market generally downdraft gasifiers are available due to utilization of mechanical mode. In this type air intake and biomass is fed at the top. Biomass moves down as the process proceeds.

The first stage consists of drying through pyrolysis oxidation and reduction. The hot gas coming out of the Gasifier has significant carryover of ash and soot particles. The gas is passed through cyclone and scrubber for cleaning and cooling. The clean and cool gas is than further passed through fine filter and fed into a diesel generating set to run the engine or for direct heat application.

Commercial Benefits of Biomass

November 18, 2009 Leave a comment

Commercial Benefits:

  • Anaerobic Digestion can generate income by charging gate fees, selling biogas (as electricity or heat), and liquor or fibre products.

AD can produce savings by avoiding the costs of synthetic fertilizers, soil conditioners and energy from other sources.

In an anaerobic digestion plant, there are two types of AD process:

  • Mesophilic digestion
  • Thermophilic digestion

There are four key biological stages of anaerobic digestion:

  1. Hydrolysis
  2. Acidogenesis
  3. Acetogenesis
  4. Methanogenesis

Power Generation:

The power potential from sewage works is limited – in the UK there are about 80MW total of such generation, with potential to increase to 150 MW, which is insignificant compared to the average power demand in the UK of about 35,000 MW. The scope for biogas generation from non-sewage waste biological matter – energy crops, food waste, abattoir waste etc is much higher, estimated to be capable of about 3,000MW.

Disadvantages of Bio-Fuels

November 11, 2009 Leave a comment

As of right now even though bio-fuels produce much lesser green house gases the machines that are used to cultivate and produce them still have some problems with carbon emissions so we still need to work on newer ways to produce them in a more greener way.

Our technological processes to produce bio-fuels are way too costly for us to be able to afford on a massive scale. We still need billions of dollars of research money into having a manufacturing process that will produce them at a cheaper rate.

We still don’t have anywhere near the amount of bio-fuel converted cars to be able to take advantage of this fuel source. We will need to invest trillions of dollars to change the automobile infrastructure to allow us to take advantage of this awesome natural fuel.

Setting aside land to grow bio-fuels means that there is less land to grow food. Some people contend that this will lead to more people around the world starving as there will simply not be enough food to feed everyone. It is also possible that food prices will rise as a result.

More land must be set aside to make bio-fuels. Natural habitats may be lost as a result.

Burning corn may release high concentrations of nitrous oxide into the air, which is a greenhouse gas.