USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS.

Transcription

1 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. John Vourdoubas TEI of Crete Department of Natural resources and Environment Chania

2 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. Burning of solid biomass is the simplest way for its energy exploitation. For improving burning process the water content of solid biomass should be less than 20%. Many times it is necessary to cut solid biomass in small pieces so it can be used better for burning in various systems. Solid biomass is composed mainly from cellulose and lignine

3 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. During biomass burning there are three factors affecting the fire that is: Fuel Oxygen and Heat Controlling those three factors, the fire can be controlled.

4 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. Heat produced during burning can be transferred with three mechanisms: With conductivity With radiation With transfer

5 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. Burning of wood has the following three characteristics: Wood is burnt in two stages. First volatile gases are produced and after that they are burnt to produce charcoal which is also burnt afterwards. Oxygen should be transferred from air to the burning zone. The placement of wood in the fireplace affects the burning process.

6 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. It is very important to reduce the heat losses during biomass burning. This can be achieved with various ways and affects seriously the economics of biomass heating. Heat that is dissipated with exit gases can be partly recovered to increase the efficiency of the process.

7 C ( H O ) + 6 no 6 nco + nh O 6 n 2 5 n USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. The existing fireplaces to day have efficiencies which vary from 20% to 80%. The Chemical reaction during biomass burning is C 6n (H 2 O) 5n +6nO 2 6nCO 2 +5nH 2 0

8 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. The efficiency of a biomass heating system is defined as Efficiency = Usefull thermal energy Energy of biomass Since the exit gases are creating pollution problems they should be processed.

9 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. To improve burning process it is suggested Burning temperature should not be lower than 850 o C. Residence time of gases in burning zone should be greater to 1,5sec. The ratio air/biomass should be controlled. Good mixing of the fuel with air is necessary.

10 C ( H O ) + 6 no 6 nco + nh O 6 n 2 5 n USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. The oldest use of solid biomass for heat generation is burning. The efficiency of this process is low, usually lower than 40%. The traditional fireplaces have efficiencies 10-20%, but some new designs achieve higher efficiencies in the range 60-80%.

11 Conventional heating system of a house using wood

12 A low energy efficient fire place

13 An energy efficient fire place

14 An energy efficient fire place

15 Principle of operation of an energy efficient fire place

16 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS In areas where olive tree is growing, heating systems using olive Kernel wood are popular. Olive Kernel wood is a cheap fuel in comparison with oil or natural gas. Its heating value varies between Kcal/Kg and its water content is 8-10% p.w.

17 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS The burner of a heating system using olive Kernel wood is different than the corresponding burner af a system using oil. A house with heating needs Kcal/h, uses 6Kg/h of olive Kernel wood. If the same house uses oil as fuel, it needs 1,87Kg/h. Comparison of the cost of two fuels shows that olive Kernel wood is much cheaper than oil.

18 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Apart from olive Kernel wood, various other types of solid biomass like agricultural and forest residues can be used as fuels. Olive Kernel wood is also used for heat production in various Small and middle size companies.

19 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Some agricultural greenhouses use as fuel olive Kernel wood since it is cheap and satisfactory temperature control can be achieved inside the greenhouse. Recently various hotels in Grete use the same fuel for space and water heating mainly because of its low price.

20 Typical Chemical Analysis of Olive kernel wood. Water content 6.30% Ash 8.80 % Organic matter 65,50% Sulphur 0,11 % Chlorine 0,69% Total Carbon 45,30% Hydrogen 5,17% Nitrogen 1,33 % Oxygen 34,30% Heating value kcal/kg 16,96 MJ/kg Residual oil 2,44% Residual hexane < 10 mg/kg

21 Olive kernel wood produced in the factory

22 Heating system of a greenhouse using olive kernel wood

23 Heating system for a house using olive kernel wood

24 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Solid biomass is also used for briquettes production. In this case recycled waste wood can be used for the production of the briquettes. The briquettes are handled easily and is a standardized product for burning purposes.

25 Waste wood for recycling to produce wood chips

26 Wood Briquettes producing system

27 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Recently solid biomass is broadly used for wood pellets produstion. They present various advantages like: Low ash content High heating value,highter than 4.000Kcal/kg Low concentration of air pollutants in burnt gases

28 Wood pellets

29 WOOD PELLETS SPECIFICATIONS IN AUSTRIA Water content < 12 % Ash < 0,5 % Heating value > 18 MJ/kg Sulphur < 0.04 % Nitrogen < 0,3 % Chlorine < 0,02 %

30 PROPOSED WOOD PELLETS SPECIFICATIONS FOR EU COUNTRIES Water content <10 % Ash <0,7% Heating value > 16,9 MJ/kg Sulphur <0.05 % Nitrogen 0,3-3 % Chlorine 0,03-1 % Additives < 2 % on dry basis

31 Heating system using wood pellets

32 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Wood pellets are burnt in special systems and cover all the heating needs of a house for space heating and hot water production

33 Heating a house with wood pellets

34 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS To day in Crete solid biomass is mainly used for heating purposes in Buildings, greenhouses and Industries, but not for power generation. Also small quantities of biogas produced from the sewage treatment plants in Chania and Heraklion are used for cogeneration of heat and power.

35 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS To day Biomass contributes significantly to the energy needs of Crete, covering 8,5% of all its energy needs. Wind power and solar thermal energy contribute less in covering the energy needs of Crete.

36 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS There are many benefits from the use of solid biomass for heating purposes, including environmental, social and economical. It should be pointed that the use of biomass for energy generation creates more new jobs in comparison with the use of solar or wind energy.

37 Solid Biomass small size heating systems SYSTEM Fire places Special systems Special burning systems Fire places Various FUEL Ordinary wood Wood pellets Olive Kernel wood Briquettes Agricultural and forest residues

38 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. Although the use of solid biomass for heating purposes creates CO2 emmissions, it is considered that it is CO2 neutral. This is why the CO2 emmitted during biomass burning, is absorbed from the atmosphere during photosynthesis and creation of the same biomass quantity.

39 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS. The use of solid biomass in small scale systems for heating buildings will reduce the CO2 emmissions from them and the use of fossil fuels for energy generation in them. This is important as the EU directive 2002/91/EC concerning the energy performance of buildings is applied all over Europe.

40 JOB CREATION FROM VARIOUS ENERGY SOURCES PER UNIT OF INSTALLED POWER Lignite 1 Wind 0,9 PV 2,5 Solar thermal 1,4 Hydroelectric 1,2 Biomass 2,4 Geothermal 2,6

41 CO 2 changes during biomass burning and photosynthesis

42 USE OF SOLID BIOMASS FOR HEATING PURPOSES IN SMALL SCALE SYSTEMS Thank you for your kind attention