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Biomass

 

Introduction

Biomass resources can be subdivided into three categories: wastes, forest products and energy crops. There are several methods available to covert biomass into useable form of energy. The foremost among them is thermal conversion where combustion, gasification and pyrolysis are used to retrieve energy from biomass. The next is biochemical conversion where micro-organisms during fermentation, anaerobic digestion and composting release energy from biomass. The last is the chemical conversion where various chemical reactions draw out energy from biomass. Apart from being used directly, biomass energy can also be converted from one form to another.

Using biomass for energy production, would replace a significant amount of imported energy with a new, local source, generating employment for citizens through the construction and operation of biomass energy plants, and especially through the ongoing harvesting and processing of the biomass fuel supply. Using locally available forest resources (that are currently left as logging waste) represents an additional economic development opportunity.

 

Available Technologies

Combustion

In the case of combustion, biomass is burnt and the hot combustion gases are used to raise steam, in much the same way as in a heating system. The steam is then used to drive a steam turbine, which drives a generator to produce electricity. Virtually all the existing wood-fired electricity generating plants in the world are steam turbine systems, as are most fossil fuel-fired plants. The conversion efficiency from primary fuel to electricity is fairly low, especially for small systems, but the capital cost is also relatively low and the technology is very mature and reliable.

Co-firing

Co-firing is the combustion of multiple fuels in the same energy system. This usually means mixing a small percentage of solid biomass with coal to fuel a large power plant. Burning biomass in a coal plant can increase equipment performance and reduce pollution. In most scenarios the solid biomass must be low cost to justify modifying the power plant. The volume of supplemental biomass fuel required for a large coal-fired power plant is often comparable to the volume required by a small wood-only plant.

Gasification

If biomass is heated with a restricted supply of air, combustible gases will be given off. These gases can be purified and used to drive an engine: this might be a reciprocating internal combustion engine (like a car engine) or a gas turbine (like a jet engine). The engine is used to turn a generator to produce electricity. Gasification can give higher efficiency than combustion plant, while gasifier systems can be used for systems of virtually any size. The ability to produce a gaseous fuel from solid wood can provide an increased level of flexibility and convenience in terms of fuel storage and transportation.

Liquid biofuels

Liquid biofuels such as ethanol, methanol, bio-oil, and biodiesel can be produced from biomass through pyrolysis, fermentation, and other methods for transportation and bio-refining. Current feedstocks for these fuels include corn, soy, and other agricultural crops. Advanced conversion technologies for cellulosic feedstocks such as wood and other plant fibres may become commercially viable within a few years.

Anaerobic digestion: it is a method engineered to decompose organic matter by a variety of anaerobic microorganisms under oxygen-free conditions. The end product includes biogas (60–70% methane) and an organic residue rich in nitrogen. This technology has been successfully implemented in the treatment of agricultural wastes, food wastes, and wastewater sludge.

 

Emerging biomass utilization technologies

Technology/Process

State-of the Art

Main Challenges

Combustion

Commercial available, low efficiency at small scale

Feedstock variability, feedstock contamination, combustion stability

Gasification

Demonstration scale

Cost reduction, gas quality

Anaerobic digestion

Commercial status but high costs, low efficiency and low yield

Scale-up, cost reduction and use of mixed wastes

Processes to bio-diesel

Proven technology, high cost and low yield

Cost reduction and continuous production

Fermentation to bio-ethanol

Commercial status, high cost, low yield

Cost reduction, higher yield

 

Identification and description of the main territorial constraints and stakes

Biomass is an abundant renewable resource, with long traditions of use in most civilizations. It is the only renewable energy resource that can easily be converted to satisfy all energy sectors: heat, power and liquid fuels for transport. It is also the only way that solar energy can be stored in large quantities. Biomass production is part of the natural eco-cycle and virtually all over the world there is long-term experience of large-scale biomass production, as well as its use for energy purposes. With biomass branch staying high in the European political agenda and the recent documents highlighting the crucial role of biomass to reach the "20-20-20" targets, it is important for each Region to identify the main constraints and to determine market deployment prospects. They are related to the following phases of biomass energy chain: feedstock availability (valuation of biomass supply), land availability (food production vs. alternative land use), biomass transport (cost, environmental impact and greenhouse gas emissions), biomass storage (logistics and costs) and finally, conversion processes (technologies and efficiency improving).

 

SWOT ANALYSIS

The biomass option to be considered are herbaceous energy crops, short rotation woody crops and agricultural and forest residues, which would enhance local and regional productivity and reduce farmland abandonment. With regard to conversion technologies we considered a fluidised bed combustion, which is already developed and use to a higher degree.

STRENGTHS

  • The production of biofuels contributes to secure energy supply
  • The use of biofuels can reduce Greenhouse Gas Emissions (GHG)
  • Due to a longer value chain within the national boundaries, biofuel production creates new employment
  • Feedstock production for energy purposes creates jobs especially in rural areas
  • The production of biofuels creates an additional distribution channel for agricultural products and rise the income for farmers
  • Reduction of GHG emissions and of environmental impact of agriculture due to low water, fertilizer and pesticide requirements of this crops
  • The chain reduced the risk of fire due to forest residue abandonment
  • Use of marginal land and implement of rural land management
  • The biomass chain can be characterized by relatively short transport distances (locally produced and locally used).

WEAKNESSES

  • Periodicity of biomass availability
  • Land consuming and possible competition with food crops
  • Experience with new energy crops is scarce, or in any case non-commercial
  • Management practices for energy crops different for traditional crops and need some changes for agricultural and forest residues, and therefore they require follow up of machineries and of logistic
  • Storage needs more space than in the case of competitive fuels
  • Operation and maintenance of biomass plants need specialised workers
  • Biomass are characterized by lower energy content per volume than fossil fuels
  • Combustion is characterised by low electrical efficiency if the residual heat is not employed
  • Specialised biomass market is not available and this delays the sector development
  • Market prices do not reflect environmental costs and damage and that mask the striking environmental advantages of the new and cleaner energy options

OPPORTUNITIES

  • Existence of uncultivated land in the region (about 20% of total agricultural area)
  • Biomass has the opportunity to replace a large percentage of fossil fuels
  • Biomass can decrease dependency and import on crude oil
  • Presence of agricultural and forest residues in the region
  • Favourable legislative framework for RE implementation
  • Effects on rural employment and development
  • Increased energy security in the region
  • Feedstock production for energy purposes can reduce agricultural premiums and subsidies
  • New and more efficient conversion technologies will be found and existing technologies will be improved.

THREATS

  • Local availability of biomass
  • Low fertility of marginal land and distance to the farm centre
  • Biomass production is limited due to land availability for feedstock production
  • Small farms with low opportunities of investment consequently need to form consortia
  • Transportation network has low quality and some rural areas are difficult to reach
  • Depopulation of rural areas
  • Political variability and conflicts with local stakeholders
  • Limited access to information, particularly with regard to available technologies

 

 

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