Answer:
There are many difficulties that are to be faced while using biomass.I have collected them and are printing them here...
-2ndGeneration biofuels:Cellulosicfeedstock (wood, crop residues and grasses, paper -from municipal waste) the technology is yet to reach acceptable levels of economic viability
Direct combustion
Pyrolysis(Destructive distillation)
Anaerobic digestion
Alcoholic fermentation
Gasification
Carbonization (Conversion into charcoal)
Oil extraction and trans-esterification
Difficulties
Low concentration of biomass per unit area of land and water
Scarcity of land for food drops and energy
High moisture content that make transportation expensive and energy conversion inefficient
Land degradation arising from charcoal harvesting
Haphazard wood harvest causes severe environmental damage reduced supply of woodfuel
Pertinent need to improve the efficiency of wood burning stoves to minimize the concentration of pollutants environmental concerns
Assessment of health effects of emissions from wood stoves and biomass conversion technologies
June 2008
Competition with other land uses such as food production
Reduction of natural plant and animal species diversity due to monoculture -less stable ecosystem
Invasiveness of certain plant species
Deterioration of soil quality due to continuous use of pesticides and fertilisers
Increase in the prices of food products
Air pollution from the combustion of woodfuel(Low combustion efficiency and therefore high emissions of Carbon monoxide, particulate matter especially during the cold seasons (high concentration of wood stoves);
Polycyclic Organic Matter (POM) emissions such as Benzo(a)pyrenewhich are known carcinogens are the most dangerous components
CO emission from the equipment used for harvesting, chipping and transport equipment
Use of wood instead of coal significantly reduces SO2emissions from coal fired plants
Corrosive effect of sulphurousand sulphuricacid from the reaction of H2S with water.
Air pollution: fugitive dust from raw material and product handling; organic vapoursfrom the distillation process; volatile organic compounds; odoursfrom fermentation tanks
Safety: Explosiveness of the gas in confined environments (leaks)
Odourfrom H2S in biogas
Decentralisedethanol production may not be favourablefor monitoring environmental conditions and enforcement of environmental standards
16th June 2008 21
Impacts on water sources by the leaching of biomass storage pile
Energy requirements, wastes from the distillation process and hazards associated with the use of toxic chemicals
Damage of aquatic ecosystems arising from stillage(High biological and chemical oxygen demand)
Reduction of feedlot pollution arising from run off from cattle feed lots (bacteria, suspended and dissolved solids, chemical and biological oxygen demand) especially for aquatic systems
Waste disposal problems
Effluent from biogas systems contains high concentrations of inorganic salts, H2S and NH3or even heavy metals.
Elimination of drawbacks of animal manure (disposal problems)
Removal of crop residues from land
Increased erosion and flow of sediments into surface waters
Decrease in productivity
Increased flood potential
I hope this information is handy.......