BIOMASS’ · Biomass, what’does’it’mean?!!"Biomass”!stands!for!all!organic!maer!with!a...
Transcript of BIOMASS’ · Biomass, what’does’it’mean?!!"Biomass”!stands!for!all!organic!maer!with!a...
BIOMASS Master School of Province de Liege -‐ Industrial Engineer Department
Course:
Buildings and HVAC Systems -‐ 2nd Master Academic year: 2013-‐2014
Teacher: MASY Gabrielle
Authors:
Gilles SAMSON, Fabrice VADACCA, Xavier SAP and Julien DELINCE
Biomass, what does it mean?
! "Biomass” stands for all organic ma2er with a vegetable or animal origin which can become a source of energy by combus:on.
! 3 forms of useful energy: -‐ heat -‐ electricity -‐ driving force of movement
Biomass is classified into 2 main categories depending on the humidity rate:
1. Dry biomass
2 procedures for dry biomass:
! CombusUon : it’s a complete oxida:on of the biomass to
produce heat. Hot water or steam produced in the process supplies an en:rely conven:onal central hea:ng system (E.g.: wood stove or industrial boilers).
! GasificaUon: it’s the thermal decomposi:on of the solid
biomass in a specific reactor (called gasosphère) in order to obtain a combus:ble gas.
2. Wet biomass
BiomethanaUon: organic material undergoes an anaerobic fermenta:on in a digester, and gives a methane-‐rich biogas. -‐> to produce heat -‐> to produce electricity
3. Biofuels ! Biodiesel: created from a reac:on between oil (rapeseed, sunflower) and alcohol.
[Yellow rape fields]
! Bioethanol : created from a mixture of fermented sugar and gasoline.
Biomass producUon: -‐> Plants absorb carbon dioxide (CO2) and renew the stock of
oxygen in our atmosphere. Photosynthesis produces the main cons:tuent of plants: the carbohydrates.
-‐> CO2 emissions from wood-‐fire boiler and combus:on of biogas
are neutral as far as greenhouse effect is concerned.
The funcUoning of biomass boilers
OperaUng principles: The biomass combus:on can insure the produc:on of hot water for hea:ng or con:nual supply of hot water. In order to achieve this, the biomass generator provides thermal energy to a heat transfer fluid. In this case, it uses water. A biomass boiler consists: -‐ Furnace in which you can see the fuel degrada:on and the igni:ng flame. This fireplace is previously supplied with biomass by a conveyor system from the fuel storage silo
-‐ A combus:on chamber
-‐ A heat exchanger: where the thermal energy produced from biomass in the chamber and the flue gases will be exchanged with the coolant (water)
Different types of biomass boilers: ! Wood log boiler:
The use of firewood is oVen reserved for auxiliary hea:ng, because of the need to load the equipment with logs several :mes a day. However, technologies more and more efficient can jus:fy the choice of central hea:ng with logs, especially when hea:ng needs are important and when the resource is abundant and cheap.
Different types of biomass boilers:
! Shredded wood boiler or wood chip boiler:
The wood chip boiler has a higher comfort in use than the wood log boiler: the opera:ng principles are similar to an oil or gas boiler and it is fully automa:c. However, the investment is quite high and the bulky fuel requires a storage silo. This type of boiler can only be considered for at least 250m ² of living space.
Different types of biomass boilers:
! Granules or pellets boiler: Fully automated, these boilers are
fired by wood pellets that are stored in a silo. They are sent by a worm in the furnace. The supply, the burning and the smoke extrac:on are done automa:cally. This type of boiler has a high efficiency (90%) which is similar to a fuel boiler or an oil boiler. The granules have a higher calorific value than the chips but they are more expensive.
Several kinds of biomass fuels for boilers
1. Barks of trees, a basic waste of wood industry: -‐> Be2er for high powerful systems.
2. Sawdust: Come from the cu_ng of tree trunks. Easier to use in a
smallest hea:ng system.
3. wood pellets: Come from sawdust compacted. More used in small and
middle biomass boilers.
4. wood chips: Come from the crushing of wood witch and also come
from recycling programs.
5. Other kinds of biomass fuels: -‐> From agriculture -‐> Ethic problema:c
Values of different kinds of biomass fuels
PosiUve and negaUve aspects of
biomass PosiUve aspects:
! Biomass is considered as being carbon dioxide (CO2)
neutral.
! Renewable source of energy
! PosiUve impact on the local economies: Local jobs in produc:on, transporta:on, collec:on, packaging and selling.
! Local producUon reduces the cost of transport and the risks related to fossil fuels in foreign country (Middle-‐East, Russia).
“Wood energy” is cheaper than gas and fuel oil, at equivalent
calorific value. Wood energy price doesn’t fluctuate much (1)
[Wood pellet factory] [Oil refinery]
! Biomass is a solu:on to use organic waste as combus:ble material:
-‐ Agricultural residues (manure)
-‐ Wood residues (sawdust, wood-‐pellet, unusable part of trees)
-‐ Human ac:vity residues (sludge, household waste)
NegaUve aspects: ! Storage space for “wood energy” ; fill the wood-‐burning
furnace manually.
! Overexploita:on of the woody biomass would be harmful for the natural environment
! Household waste contain inert components which must
be treated aVer burning
! The net calorific value of biomass is low contrary to fossil fuels:
-‐ From 8000 to 16000 kJ/Kg for household waste
-‐ From 5760 to 16560 kJ/Kg for wood residues.
Wood-‐pellets have the highest calorific value concerning
wood products : 16560 kJ/Kg
-‐ From 17600 to 18970 kJ/Kg for wood log
-‐ About 42700 kJ/Kg for fuel oil
(1kwh = 3600 kJ)
! Biofuels (agrofuels) : Biomass is interes:ng when it comes from by-‐products (wood
residues, waste). Biofuels (rape) come from energy crops and these crops may
occupy areas to the detriment of food-‐producing farming, forests, swamp and so on.
-‐> It can be a threat for the ecosystem, the carbon sink, the price
of food products and the water reserves.
[Yellow rape fields:]
SoluUon for our engineering school:
Wood-‐pellets boiler
• Boiler cost : around 170 000 €
• Storage space : around 75 000 €
• Power : 1,5 MWa2
Thank you for listening ☺