Energy from Biomass

• 1. What does we mean by "Bioenergy Sources"?
• 2. What advantages do bioenergy sources have?
• 3. Is there enough biomass available to create energy?
• 4. What are the technical aspects?
• 5. What are the costs involved?
• 6. What are the environmental implications of biomass energy?

Energy sources based on renewable resources are present in various forms.

Solid fuels include:

• Wood and offcuts (residues) from industrial forestry and woodland management, from saw mills or from used wood,
• Energy wood, i.e. specifically cultivated, fast-growing tree species such as poplar and willow (Short Rotation Coppice - SRC)
• Agricultural residues (straw)
• Specifically cultivated energy plants.

Important resources for liquid fuels are:

• Sugar (cane, beet, etc.) which can be used for the production of ethanol,
• Oil plants such as rape seed and sunflowers for the production of vegetable oil.

The gaseous bioenergy source is:

• Biogas, which is produced by microbial digestion of agricultural residues such as liquid manure (also sewage and landfill)

• They are renewable, i.e. efficently used they can replace a high percentage of fossil fuels.
• They are to a large extent CO2 - neutral, i.e. they do not contribute to the greenhouse effect.
• They store solar power, i.e. the sun's energy is stored and could be used when required.
• They are available in solid, liquid or gaseous forms. This means that it is possible to use them in a wide range of areas.

Biomass will substantially contribute to energy supply in future. It is possible that biomass can meet the demand on heat, electricity transportation fuels up to 17.4% in 2030.

Wood, energy plants, straw and biogas are potentially able to produce a significant share of energy susainably.

Currently, 6.8% of the final energy consumption are already provided by biomass.

The oldest and still most common use of biomass energy is combusting. Therefore, over the recent years, most research and development has been done in biomass combustion. The plants available on the market today - either small firing, domestic or larger central heating stations - have all been developed to a high technical standard. They combine high efficiency with ease of use and comfort. They meet alt least the standards of  semi-automatically and automatically fed plants or central heating systems running on natural gas or oil.
 
Wood chips are generally used for these systems. However, problems can arise from the storage of woodchips. In response to this, industrially manufactured, standardized fuel pellets have been produced. As a domestic fuel source the pellets provide a good solution since they combine high fuel quality with facilitation of transport and a long shelf-life.

A high technical standard means that biomass technology is more expensive than the established gas and oil firing technologies. Another reason why biomass systems are more expensive is because they are not widely used, so there is only little competition. Furthermore, it is technically more complex to burn a solid fuel more efficiently and more emission-friendly than a gaseous or liquid source of energy. Thus, the initial costs for biomass systems, depending on size, are approximately 1.5 - 2 times more expensive than comparable fossil fuel systems. This additional financial expenditure can be at least partly reduced by the use of existing national advancement programs.
 
The operating cost of a such a plant is essentially determined by the fuel costs. Unfortunately, no fuel market exists for biomass systems so far in Germany. Biomass energy has not been able to establish itself in the market place, so there are very strong regional price differences, too.

The bio energy, like all renewable sources of energy, is particularly pollution free in terms of its production. In the first place there is the CO2 neutrality of these sources of energy.

However, biomass energy is usually burnt, so various compounds are released into the environment. Nitrogen oxides are released, since nitrogen is main part of air used with the burn. Aromatic hydrocarbons are also released. They cause the characteristic smell of a wood fire. Depending upon fuel, these pollutants are set free in quantities. The formation of water vapour is dominant, since biomass fuels are characterized by a high water content. This water vapour leads to the production of the water vapour flags, which can be seen from far away and are often mistaken for a high pollutant output. As long as uncontaminated fuels are used, emissions can be controlled with available technologies. However, if fuels are loaded with wood preservatives, high requirements for downstream emission control is necessary. Therefore, treated fuel materials require special combustion plants and should not be used in small firing plants.