Biomass Heating on a Small Scale

Transcription

1 Biomass Heating on a Small Scale Timothy A. Volk SUNY ESF, Syracuse, NY Sustainable Use of Renewable Energy (SURE) SUNY ESF, Syracuse, NY November 4, 2009

2 US Energy Sources

3 History of U.S. Energy Use (EIA 2007)

4 Energy Use in U.S Approximately 1/3 of primary energy use in the U.S. is for thermal applications 82% of heating oil used in the U.S. is consumed in the Northeast U.S. Thermal/Other Transportation p Electric Power

5 NE US Heating Characteristics Reliance on oil as a heating source creates vulnerability to fluctuating oil prices Currently spending over $13 Billion/yr on heating oil in the NE EIA estimates that over the next 10 years heating oil will average $3.59/gallon

6 Benefits from Biomass It is a renewable, sustainable resource Fuel is available in large quantities across the northeast and elsewhere Use of local, natural resources creates independence and reinforces local networking Biomass fuel ldll dollars and dthe value added dddfrom their thi conversion stays in the local economy

7 Benefits from Biomass Large or innovative projects pave the way for other projects or industries Biomass fuel prices have historically been fairly stable Biomass price increases will be more gradual than competing fuels Future energy and carbon taxes should not impact biomass bo fuels ues Low grade markets can improve opportunities for sustainable forest management

8 Common Concerns Higher capital and M&O costs Biomass fuel requires more attention during operation Attention to fuel quality is required May have to build and maintain a local fuel supply network Concerns with emissions from burning biomass Biomass systems may require more maintenance than conventional fuel systems

9 Prices of Residential Heat Sources in MA MMBtu $/M (Kingsley 2009)

10 Heating Cost Assumptions Fuel Heating Value Efficiency Wood Pellets 16.4 million BTU/Ton 83% Firewood 20 million BTU/Cord 77% Coal - Anthracite 25 million BTU/Ton 80% Fuel Oil #2 134,500 BTU/Gal 83% Natural Gas 1.03 million BTU s per MCF 80% Propane 91,200 BTUs Per Gallon 80% Electricity 3413 BTU/Kwh 100%

11 Heating Costs by Fuel Type Fuel Cost $ per MBTU Annual Fuel Costs** Wood Pellets 250 $/ton Firewood 250 $/cord Coal 200 $/ton Fuel Oil # $/gallon , Natural Gas 2.16 $/ccf , Propane 3.00 $/gallon , Electric 014$/kwh ,

12 Google fuel calculator Google fuel calculator

13 Pellet fuels Institute -

14 Important Biomass Characteristics Main characteristics that influence the use of biomass as a source of energy are: heating value moisture content density chemical composition volatile matter amount of solid carbon ash content and composition, melting and slagging behavior Characteristics vary somewhat by type of plant material woody versus herbaceous species within general types handling and processing procedures

15 Higher Heating Value (HHV) the GROSS amount of heat energy released when biomass is combusted at standard atmospheric conditions and 60% relative humidity Also called the Gross Heating Value (GHV), Calorific Value (CV) or Calorimetric Value (CV) includes the calorific value of the fuel (bone dry) and the latent heat of vaporization of the water in the fuel

16 Lower Heating Value (LHV) the NET amount of heat released when biomass is combusted at standard atmospheric conditions and 60% relative humidity Also called Net Heating Value (NHV) or Lower Calorific Value (LCV), Net calorific value (NCV), Effective Heating Value (EHV) The difference between HHV and LHV is the latent heat of vaporization, which depends on the moisture content of the fuel and its hydrogen content

17 Moisture Content Fuels are often compared on a dry weight basis (0% moisture content) odt oven dry tons bone dry weight is same as oven dry Green weight is less rigorously defined term but is used to express the weight of freshly harvested biomass However, biomass is often bought and sold on a green weight basis

18 Moisture Content 9,000 Energy Contnet (LHV - Btu/lb) 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1, Moisture Content (w et w eight basis) Need dto understand dfuel moisture content t(mc) For wood ranges from <10% for wood residues up to 65% Numerous factors influence MC climate, species, harvesting method, time of harvest, length and method of storage

19 Moisture Effects If a conversion facility has been designed to use high moisture fuels, no technical problems will occur but high moisture content will impact the overall feasibility of the energy production: the more water fuel contains -> lower heating value -> fuel efficiency is lower the more water fuel contains -> bigger boiler volume needed -> more expensive boiler transportation of water is expensive because there is no benefit to the overall energy system most automated systems cannot react to rapid variations in moisture content resulting in incomplete combustion, which can change emission profiles

20 Energy Density Knowing the LHV and the bulk density of your biomass fuel allows you to determine its energy density Useful to know when planning a bioenergy project since it will effect the size of the plant, storage area needed, transportation systems, costs etc. Biomass energy density is lower than oil or medium grade coal and is a limitation that increases their delivered energy costs

21 Biomass Supply

22 Range of Sizes

23 Wood Heating System Cost-Effectiveness Biomass systems are most cost effective when: Cost of alternative fuels is high Facility energy demands are relatively large When they are an alternative to another new system rather than a replacement for an existing system When hot water or steam heating systems are already in place

24 Cost Effectiveness vs. Electric Life cycle costing study using assumptions from Appendix D in Maker (2004).

25 Cost Effectiveness vs. Fuel Oil Life cycle costing study using assumptions from Appendix D in Maker (2004).

26 Cost Effectiveness vs. Natural Gas Life cycle costing study using assumptions from Appendix D in Maker (2004).

27 Questions?

28 Biomass Energy System Components Fuel Storage Berlin, VT and Newport, VT (Maker 2004) Design for immediate and long term needs Usually below ground Easy unloading Below forest level Less obtrusive Accommodate a variety of delivery vehicles Size to accommodate 30-50% more than one full load for small systems Larger systems based on available storage space

29 Delivery Options Walking floor trucks are common Design system with some flexibility for different vehicles and types of fuels

30 Delivery Options

31 Biomass Energy System Components Fuel Storage Storage size needed Need to know system s s energy output amount of load fuel s heating value Bulk density Heating efficiency Wood storage facility (GSES 2005)

32 Storage Space Boiler output x hours of load Boiler output x hours of load LHV x bulk density x system efficiency

33 Cost Effectiveness Case Study Conversion from oil to new wood-chip heating system 220,000 ft 2 high school Capital costs (boiler system, building, hot water, engineering) - $590,000 30% VT state aid to schools for capital costs Interest rate 4.6% Term 20 years

34 Cost Effectiveness Case Study Discount rate of 5.6% 85% of heat for school from wood, rest from oil backup system Oil price - $1.00/gallon, 3% inflation Wood-chip - $28/ton, 2% inflation

35 Bulk Density Lower end is for softwoods, higher end of range is generally hardwoods

36 Measuring Moisture Content Measure fresh or wet weight of material, dry at 105 o C to a constant weight m.c. wet basis = Total wet weight of wood oven-dry weight Total weight weight of wood X 100 m.c. dry basis = Total wet weight of wood oven-dry weight X 100 Oven-dry weight

37 Moisture Content For a sample with a wet weight of 1200 g and an oven dry weight of 650 g the m.c. what is the moisture content on A wet basis? Ad dry basis

38 Moisture Content Wet basis is 45.8% Dry basis 84.6% on a dry basis Other characteristics of the biomass are the same regardless of how it is reported Moisture content is usually reported on a wet weight basis, but be sure you know what values are being used