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Why Biofuel and Energy Peat?

Wood fuel is one of the principal parts of biofuel. The most important parts of the forest biofuel are firewood and tree felling waste. Firewood is the part of tree stems which is unsuitable to processing (rots, bulges and other deficiencies). Felling waste is the part of wood, remaining after the felling of forest. Lithuania is covered by relatively large tracts of forest, forming more than a third of the overall territory of the country. Wood is a great alternative to imported fuel. Furthermore, wood is a renewable fuel, if used appropriately.

Peat is ideal for combining with other local types of fuel, such as wood and energy plants. Peat, as a local material, functions as a complementary type of fuel. Peat can compensate for the lack of wood and improve the qualitative parameters of the combustion process. A combined biofuel mixture of wood, energy plants and peat is also useful from the ecological point of view.

Lithuania, being a member state of the European Union, is committed to increasing the amount of energy extracted from renewable sources. The biggest source in this respect is firewood (wood chips) and wood felling waste. As the volume of energy generation goes up, the amount of wood products, suitable for burning, will not be sufficient eventually. Therefore, large boiler houses, in order to preserve constant quality of fuel, must be provided a fuel mixture with the addition of peat. Even smaller boiler houses require peat as complementary fuel during cold winter period.

Like wood, peat is a local material. This ensures its constant supply and quality. Furthermore, global practice shows that the prices of biofuel never experience such rapid and unpredictable changes as those of oil or natural gas. Enterprises of energy generation should take this important factor into account, when planning their activities.

Excellent characteristics

• In the combustible mass of peat, 67-70% is formed by volatile fraction (for comparison – around 85% in wood waste);
• Peat contains carbon (52% to 65%) and oxygen (26% to 36%);
• There are smaller parts of hydrogen (5-6%), nitrogen (0.6-2.3%) and sulphur (0.1-1.5%);
• From geological point of view than wood, peat is an older fuel than wood. So, peat has a higher carbon/oxygen ratio (50%-52%/40-44% in wood);
• Peat contains larger amounts of nitrogen (0.2-0.6% in wood fuel) and sulphur (0.1-0.2% in wood);
• The flash point of peat is 225°C. The initial temperature of discharge of volatile substances of peat is 100-110°C.

Long-term experience of Swedish and Finnish energy producers demonstrates that the use of wood and peat mixture as fuel slows down the wear and tear of boilers, compared to using wood chips only. Therefore, such a mixture is chosen in order to improve and prolong the longevity of boilers.

The energy value of wood and peat is very similar:

Characteristics	Energy Milled Peat	Energy Sod Peat	Energy Peat briquettes / half-briquettes	Wood chips
Calorific capacity*, kcal/kg	~ 2200	~ 3000	~ 3300	~ 2200
Energetic value, MWh/t	2,8	3,4	4,7	2,4
Ash formation, %	3,5-7	2,5-5	15	0,5
Moisture, %	38 to 52	33 to 45	Up to 22	Around 50-60
Amount of sulphur, %	0,13	0,12	0,19	0,2
Suitable for combusting in boiler houses	Yes	Yes	Yes	Yes

* Calorific capacity of fuel depends on moisture. The calorific capacity, provided in the table, is medium value at the moisture value, given in the table below.

Suitability for boiler houses

“Vapo Oy”, one of the founders of “Bioenergija LT”, has been working with great success in Scandinavian countries for many years. Finland and Sweden are among the leaders of bioenergy generation, therefore industrial production of this type of energy has much older traditions in these countries than in Lithuania. Various types of boilers are used in these countries, and their installed capacity can be as high as 100 MW. Some of the boiler types are known and used successfully by Lithuanian heat producers. One of the most popular is the “fluidised bed” boiler, used for combusting the mixture of milled energy peat and wood chips. Many of the boilers designed to be used with biofuel on the basis of wood chips can introduce energy sod peat to such mixture with high efficiency. Experience shows that such a modified mixture increases the amount of generated energy.

Cheaper Fuel

In spite of noticeable price increases of biofuel due to various factors, the price of energy generated with the use of such fuel is significantly lower compared to oil, which is still widely used, or much more popular natural gas. The table on the left provides information on dynamics of price increase of the recently more popular fuel types.

On the basis of the data given in the table of energy values (Wk) and normative fuel inputs (Ck) of fuel types, established by the “Normative Values of Inputs of Different Types of Fuel for Heating of Homes and Pre -Heating of Cold Water and Methodology of Their Application”, approved by the Decision No. O3-116 of 22 December 2003 of the State Commission of Price and Energy Control, we have performed calculations of inputs of some of the most popular fuel types per unit of energy:

Fuel type	Price	Measurement unit	Normative fuel inputs, Ck	Measurement unit	Measurement unit	Measurement unit
Oil	508.00	€/t	0.0853	kg/kWh	0.04 €/kWh	43.36 €/MWh
Natural gas	0.22	€/m3	0.1075	nm3/kWh	0.03 €/kWh	34.25 €/MWh
Peat	29.00	€/t	0.3717	kg/kWh	0.01 €/kWh	10.77 €/MWh

The medium normative values of inputs (Ck) of other types of fuel (wood chips and their crumbs, sawdust and their briquettes, straw, etc.) are established by municipalities in co-ordination with the Commission, but one can assume that wood chips are similar to peat by price and values of input.