Decentralized Biomass Power Production

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Timothy Blair
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1 Decentralized Biomass Power Production by Dr. Eric Bibeau University of Manitoba (Alternative Energy Research) Biomass Energy II Heat and Power Workshop November 13, 2003

2 Activity at U of M biomass alternative energy OUTLINE Small distributed BioPower Barriers to distributed BioPower in Canada

3 Biomass Activity at U of M Dr. Ying Chen (Bio Resources) conversion of flax chives into pellets Dr. Jan Oleszkiewicz (Civil Eng) anaerobic digesters Dr. Nazim Cicek (Bio Resources) downdraft gasification system for the disposal of City of Winnipeg bio-solids and the production of biogas

4 Biomass Mech. Eng. at U of M Anaerobic digesters lagoon type cold climate (proposal stage) numerical model of flow and digestion Biomass conversion using supercritical conditions production of biogas supercritical loop Distributed BioPower generation build experimental / demonstration facility

5 Alternative Energy Research at U of M Drs. Fraser, Naterer, Bibeau (Mech Eng) Wind icing Kinetic turbines Saline geothermal Research Programs Manitoba Hydro Alternative Energy Western Canadian Fuel Cell Initiative Neptune

6 SMALL BIOPOWER (< 3MWe or < 15 B line trucks/day) Fast pyrolysis Slow pyrolysis Gasifier Air Brayton cycle Steam cycle ORC Entropic cycle

7 Fast Pyrolysis - Bio Oil Produce liquid bio-oil that can be transported or used locally and can fuel a turbine or ICE add heat and no oxygen to biomass (break down large molecules) 75% organic vapor (liquefy into bio-fuel) 10% pyrolysis gases (used for process) 15% charcoal (sold) Advantages for small BioPower concentrates energy to higher heating value fuel than original biomass lessens cost of energy transport produces some value-added chemicals that can be separated

8 Fast Pyrolysis - Bio Oil Disadvantages for small BioPower produces char/ash that must find a different disposal or market energy of biomass left in the char is normally not recovered fuel must be dry as moisture dilutes bio-oil dry fuel also produces significant quantity of dilution water in bio-oil quality of product fluctuates with variations in biomass relatively complex equipment for small BioPower

9 Travelling Bed (fast pyrolysis) BIO-OIL OIL FAST PYROLYSIS Rotating Cone (fast pyrolysis) Bubbling Bed (fast pyrolysis)

10 Slow Pyrolysis - Bio Oil Advantages for small power same as Fast Pyrolysis simpler equipment and process compared to Fast Pyrolysis Disadvantages same as Fast Pyrolysis less bio-oil produced and more charcoal need to sell charcoal Screw Type (slow pyrolysis)

11 Gasifier - Producer Gas Gasify biomass by sub-stoichiometric combustion produce a volatile gas containing carbon monoxide, hydrocarbons, hydrogen, water vapour gas relatively clean but contains particles, ash, tars Gasification drying stage pyrolysis stage oxidation stage reduction stage Operates at low pressure one system maintains pressurized conditions in gasifier (Cratech)

12 Gasifier - Producer Gas Advantages for small BioPower allows the use of engines and turbines (Brayton Cycle) may produce less particulate emission (typically still above regulatory limits) Disadvantages for small BioPower flue gas requires cleaning: cyclones and filters producer gas is cooled before being used as a fuel required to clean gas from tar energy is lost due to cooling of gas required as hard to compress hot gases requires operator knowledge to run well quality of gas fluctuates with variations in biomass feed energy of biomass left in the char/ash reject

13 Combustion Brayton Cycle Air is compressed, heated by hot flue gas in an indirect heat exchanger & expanded through an air turbine recuperation of heat may be accomplished indirect heat exchanger keeps particulate from impinging on turbine blades allows atmospheric combustion Advantages for small BioPower does not need government certified operators does not use a boiler conceptually simple all energy in biomass available for conversion

14 Combustion Brayton Cycle Disadvantages for small BioPower low efficiency (typically <10%) increased compression/expansion ratios require additional turbine stages diminishing effectiveness of each additional stage large equipment due to voluminous nature of air turbine must be almost double the size of that required by a Rankine cycle air compressor absorbs almost half of turbine power system cost is relatively high ($/kwe) large equipment/low efficiency

15 Combustion Steam Cycle Steam Rankine Cycle most common approach to energy recovery from biomass water is boiled, superheated, expanded through a turbine, condensed and compressed in liquid water form Advantages small BioPower system well known technology strong base of expertise commercially available equipment all the energy in biomass available for conversion Disadvantages small BioPower system very costly in small power sizes (<3 MW) large equipment

16 Combustion Steam Cycle Disadvantages small BioPower system steam voluminous at low pressures poor turbine efficiency in smaller sizes highly qualified, government certified operators often required chemical treatment of working fluid, de-aeration, vacuum system electrical power production must be reduced significantly to obtain cogeneration heat flue gas exhaust temperature typically 290 C need to remove particulate

Combustion - Organic Rankine cycle Uses an organic working fluid higher exit turbine pressure Advantages small BioPower smaller condenser and turbine equipment due to higher turbine exhaust pressure

17 Combustion - Organic Rankine cycle Uses an organic working fluid higher exit turbine pressure Advantages small BioPower smaller condenser and turbine equipment due to higher turbine exhaust pressure conversion efficiency is better than simple steam systems does not need chemical treatment, de-aeration or vacuums may not need government certified operators better suited to smaller power sizes than steam systems all energy in biomass available for conversion

18 Combustion - Organic Rankine cycle Disadvantage for small BioPower organic fluid ¼ of water enthalpy hot oil transfer loop required to separate the organic cycle from the hot flue gas systems are expensive relative to large steam system on a $/kw basis electrical power production must be reduced to obtain cogeneration heat flue gas exhaust temperature typically 350 C representing greater un-recovered energy

turbine and equipment due to higher turbine exhaust pressure does not need

19 Combustion System - Entropic Cycle Rankine cycle adaptation not yet published pre-vaporized fluid entering heater Advantages for small BioPower small turbine and equipment due to higher turbine exhaust pressure does not need chemical treatment, de-aeration or vacuums does not need government certified operators

20 Combustion System - Entropic Cycle Advantages for small BioPower uses a flue gas heater similar to air heater single heat transfer loop no dynamic seals produces more power than ORC or simple steam systems ideal for cogeneration: coolant 60 C (in) 90 C (out) less coolant is required to be pumped through the system dry air cooling can reject unused heat

21 Combustion System - Entropic Cycle Advantages for small BioPower flue gas exhaust temperature typically 215 C to maximize recovered energy combustion releases all of the energy in the biomass to make it available for conversion Disadvantages for small BioPower restricted to small power sizes (<3 MW) system has not been demonstrated commercially special design of turbine particulate removal from flue gas

22 BioPower Applications forestry waste OSB & MDF diesel communities greenhouses forest thinning fire control forest health agricultural wastes animal wastes municipal wastes

23 Barriers to Small BioPower Public Utilities mandated to deliver affordable power residential rates 4.3 cents US commercial rates 3.6 cents US industrial rates 2.5 cents US strong incentive for public utilities to displace industrial rates with green power BioPower considered to be 20 MW and up but many biomass sources cannot be transported economically to a centralized location do not want to run BioPower plants themselves

24 Barriers To Small BioPower Public Utilities decentralized power not main focus or mandate indirect subsidies for diesel generation Industry producing biomass wastes low industrial electrical rates IPP strong requirement for cogeneration economics to provide an incentive for companies to invest want over 3 MW due to complexity in obtaining financing and license to operate

Water Quality Management Nutrient Research and Biomass Production

Water Quality Management Nutrient Research and Biomass Production Dr. Eric Bibeau Mechanical & Industrial Engineering Dept Manitoba Hydro/NSERC Chair in Alternative Energy Conference event by Frontier