Biomass & CHP Opportunity for NC Alex Hobbs, PhD, PE NC Solar Center www.ncsc.ncsu.edu Sierra Club Forum November 14, 2009
Living within our energy budget Carbon production cycle based on agricultural biomass for production of hydrocarbon based energy and products
Energy from the Sun An sustainable supply of energy for the next few billion years & nuclear energy we all support 150 x 10 6 km The Sun destroys 4 x 10 9 kg/s of mass and releases energy at the rate of 3.8 x 10 26 J/s. Diameter = 1.39 x 10 6 km Weight = 2 x 10 30 kg Diameter = 12,700 km Earth 32’ ≈ .53° E = mc 2 One billionth of the Sun’s radiation actually reaches Earth 178,000 Terawatts Where 1 tera is 10 12 Surface solarization = 1000 W/m 2
NC’s most widely deployed solar collector Woody Biomass 6 CO 2 + 6 H 2 O + Sunlight -> (CH 2 O) 6 + 6 O 2 nutrients Solar Powered Biomass
Long View of Climate Change
Venus, Earth & Mars were 96% CO2 originally
Carbon has been sequestered into the earth’s crust for 3+ billion years
With current growth in fossil fuel usage we will release all fuel grade carbon to the atmosphere in ~ 200 years
World carbon balance
Natural decomposition of 100 kg of biomass: 111.7 kg CO 2 + 6.5 kg CH 4 = 248.2 kg CO 2 -equiv If 100 kg biomass were to completely decompose aerobically or combusted: 185.4 kg CO2 GHG effect reduced by 62.8 kg per 100 kg of biomass Avoided Biomass Decomposition 100 kg biomass (bone dry) (50.6 kg carbon) 46% landfilled 54% mulched 90.0 kg CO 2 (24.6 kg carbon) 90% aerobic 54 kg biomass (27.3 kg carbon) 14.8 kg CO 2 (4.05 kg carbon) 5.4 kg CH 4 (4.05 kg carbon) 46 kg biomass (23.3 kg carbon) anaerobic decomposition 50% to CO 2 50% to CH 4 40.5% captured and combusted 59.5% released as CH 4 5.4 kg CO 2 (1.5 kg carbon) 2.9 kg CH 4 (2.2 kg carbon) of the non-lignin lignin and 50% resistant to degradation 15.2 kg carbon degradation of 50% of cellulose & hemicellulose 8.1 kg carbon 10% oxidized by soil microbes 1.5 kg CO 2 (0.4 kg carbon) 90% not oxidized by soil microbes 4.9 kg CH 4 (3.65 kg carbon) 10% anaerobic decomposition 3.6 kg CH 4 (2.7 kg carbon)
Life Cycle CO 2 and Energy Balance for a Direct-Fired Biomass System Direct-Fired Biomass Residue System 134% carbon closure Mann and Spath (1997). NREL/TP-430-23076 Net greenhouse gas emissions -410 g CO 2 equivalent/kWh Landfill and Mulching Transportation Construction Power Plant Operation 10 3 1,204 1,627 Avoided Carbon Emissions 1.0 Fossil Energy In Electricity Out 28.4
Environmental Advantage of Biomass Based Energy Production NREL LCA studies by Mann & Spath
Wood Biomass to Electricity 45 MWe Craven County Wood Energy (CCWE) Operating since 1990 at 95% availability
Biomass R&D Act of 2000 Source: Martin Holmer Management Harvesting Environmental sustainability
Let’s focus on Southeastern energy issues In the Southeast what types of reasonable “solutions” may be provided through policy and technology changes?
Southeast has relatively cheap power Risk of dying from coal fired power plant caused particulates Source: Clean Air Task Force http://poweringthesouth.org
NC and GA – two of most inefficient energy economies in the U.S. Source: U.S. Department of Energy, Energy Information Administration. 2006
World’s 50 largest GHG producers North Carolina 24 th in World World’s largest emitters – 9 of 50 are southeast U.S. states Georgia 22 nd in World Florida 17 th in World Source: Pew Climate Center presentation to NC Climate Change Commission, 2006 Virginia 31 st in World
Consider CHP for efficiently using biomass for power production
Promote distributed generation using available “opportunity” fuels
Utilize waste heat from the natural inefficiency of power generation
Strive to reduce carbon emissions to the atmosphere
Support the process to establish policies that allow change to occur
Efficiency Benefits of CHP
Efficiency gains translate to emission reductions
NC REPS Definition of Biomass
The NCUC decided not to expand the definition of biomass specified in N.C. Gen. Stat. § 62-133.8(a)(8): “agricultural waste, animal waste, wood waste , spent pulping liquors, combustible residues, combustible liquids, combustible gases, energy crops, or landfill methane; or waste heat derived from a renewable energy resource.” Further determination of what constitutes a qualifying biomass resource may be made on a case-by-case basis
The conversion of woody biomass to energy in the NC poses a unique opportunity to address three issues:
Restoration of forest health
GHG reduction by using renewable energy alternatives
Provide economic development in rural communities
Total Biomass Thermal Fuel Value 199x10 12 Btu/yr 6650 Mw t 1662 Mwe
There is a significant proportion of the 10% NC REPS available from gleaning logging residues.
Biomass harvests can reduce site preparation costs.
Biomass markets can make management of poor quality stands profitable by making pre-commercial thinnings into commercial thinnings.
Woody Biomass “Practices” There are different opinions Practice Industry Extension Environmentalist Best Management Practices for Water Quality Approve Approve Approve Harvest Notification Dislike any sort of pre or post harvest announcement or opening to government regulation or oversight Supports Written Contract approved by NC Registered Forester to verify that BMPs were followed, documentation to pass up the commercial chain to state regulators. This is sort of a back door to post harvest notification Pre harvest notification Minimum Residual Stand for Thinning, Residue Left at Final Harvest Nope No consensus opinion 30 ft 2 /acre for thinning, 8 live 5” diameter trees/acre no harvest of advanced regeneration, 2 brush piles per acre
Do we have some questions? Alex Hobbs NC Solar Center www.ncsc.ncsu.edu
EPA CHP technology catalog
Good introduction to power technology options and heat recovery
Coverage of several efficiency measurements and where they best apply
EPA Biomass Publication
CHP applications for low Btu fuels
Provides a good review of everything from stoker boilers to gasification for powering renewable CHP
Energy Conversion Technologies Chris Hopkins-NCSU Simple Sugars Energy Products and Processes for Woody Biomass Torrefied Wood Bio-Char Bio-Oil Syngas (CO H 2 CH 4 ) Alcohol, Fischer-Tropsch Liquids Hydrolysis Pyrolitic Conversion Direct Combustion Bio-Fuels & Bio-Products Bio-Power Logging Residue, Waste Wood, Tops & Branches Hot Gas or Steam Process Heat Turbines Electricity or Combined Heat and Power (CHP) Torrefaction 300ºC Pyrolysis 400ºC Gasification 500ºC Acids & Enzymes Alcohols Fermentation & Distillation
NC Biomass Council Estimated 277 trillion Btu’s or 81billion kW t hr of biomass resource in NC http://www.engr.ncsu.edu/ncsc/bioenergy/docs/NC_Biomass_Roadmap.pdf
Notes on Biomass Availability for the EMC Chris Hopkins Outreach Associate, Forestry Extension
Components of Biomass Available for Energy and Fuels in NC
Forest harvest residues
Agricultural Residues (corn and wheat stover)
Biofuels crops (perhaps on pasture land)
Current Forest Productivity
TPO for NC 2007 data indicate we are generating about
12 million green tons of logging residue and
11.5 million other removals,
25% more than enough to satisfy the 17.6 million tons of forest residue (55% of the RPS total need) from the full implementation of the RPS
Prospective Forest Productivity
We could approximately increase our harvestable annual yield by a factor of 5.25
If all timberland stands were managed on a 50 year rotation and
Growth rates matched those of the top 25% of existing hardwood and softwood stands.
Most NC pulp mills not currently operating at full capacity
Nationally we are using less paper each year (1-2%)
NC TPO indicates about
10 million tons of pulpwood produced annually
1.5 million tons of fiber for composite products
USDA figures from the last ten years indicate:
Corn stover and wheat straw are the main sources of potential agricultural residues in NC.
Corn stover is about 74% of the agricultural residues (0.659 million BDT) and wheat straw is the bulk of the remainder (0.238 million BDT)
Hay is not a residue product, but may be available for use (1.589 million tons)
Biofuels on Pasture and Hay Land
Hay is typically grown on fallow agricultural land while pastures are usually less productive.
Hay represents about 716,000 acres, while pasture is about 3,000,000 acres.
Biofuels production such as switchgrass on pasture lands would likely be relatively low compared to typical ranges (4-9 BDT/acre)
4 BDT/acre used in this analysis.
Regions for Analysis of the Biopower/Biofuels Resources
NCSU is working with the NC Biofuels Center to develop a strategic assessment of the best fit of biomass feedstocks to potential technologies and may use the following regional breakdown for simplified analysis:
Requirments for Biofuels and Biopower Production
Biopower was assumed to require 8.8 million BDT annually at full RPS implementation or 1.466 million BDT from each region.
Biofuels production is proposed to be 600,000,000 gallons annually
Assume 80 gallons of fuel per BDT of biomass.
7,500,000 BDT required statewide,
1,250,000 BDT from each region
Biopower and Biofuels production is assumed to be equally shared among regions.
Constraints and Improvements of Biomass Availability
Availability describes participation in biomass markets, assumed to be 90% for all biomass sources in this analysis
Recovery is the technical ability to bring available biomass to market
75 % from recent experience with the logging industry
60% from agriculture literature
100% for hay and biofuels crops
Yield gain describes increase in production foreseen under improved management scenarios (2 is considered a conservative forestry increase, i.e., 100% increase)
Biomass vs. Biofuels and Biopower
Red indicates regional biopower goal not met.
Yellow indicates biopower goal met, partial fulfillment of biofuels goal.
Green indicates both goals met.
Numbers in table are cumulative over
Other forest residue,
Base Case: Current Productivity, Recovery and Availability Logging Residues Other Forest Residues Pulpwood Crop Residue Hay Pasture to Switchgrass Availability 0.9 0.9 0.9 0.9 0.9 0.9 Recovery 0.75 0.75 1 0.6 1 1 Yield Gain 1 1 1 1 1 1 Total 0.675 0.675 0.9 0.54 0.9 0.9 Regions Cumulative Sum of Biomass Sources 1 2 3 4 5 6 Logging Residues 521,996 589,281 801,593 1,124,893 607,084 422,309 Other Forest Residues 1,057,529 1,182,391 1,570,654 2,180,129 1,142,855 804,977 Pulpwood 1,670,130 1,841,674 2,361,622 3,222,692 1,610,893 1,158,497 Crop Residue 1,686,060 1,927,704 2,415,237 3,393,891 1,810,264 1,439,461 Hay 1,923,458 2,470,064 2,695,526 3,551,121 2,014,530 1,448,090 Pasture to Switchgrass 3,778,922 6,604,488 5,353,583 5,104,002 2,085,936 2,041,960
Improved Forest Production Scenario with Current Recovery and Availability Logging Residues Other Forest Residues Pulpwood Crop Residue Hay Pasture to Switchgrass Availability 0.9 0.9 0.9 0.9 0.9 0.9 Recovery 0.75 0.75 1 0.6 1 1 Yield Gain 2 2 2 1 1 1 Total 1.35 1.35 1.8 0.54 0.9 0.9 Regions Cumulative Sum of Biomass Sources 1 2 3 4 5 6 Logging Residues 1,043,992 1,178,562 1,603,186 2,249,786 1,214,167 844,617 Other Forest Residues 2,115,059 2,364,782 3,141,308 4,360,258 2,285,711 1,609,955 Pulpwood 3,340,260 3,683,349 4,723,244 6,445,384 3,221,786 2,316,994 Crop Residue 3,356,190 3,769,379 4,776,860 6,616,583 3,421,157 2,597,958 Hay 3,593,588 4,311,739 5,057,148 6,773,813 3,625,423 2,606,587 Pasture to Switchgrass 5,449,052 8,446,163 7,715,205 8,326,694 3,696,830 3,200,457
Satisfying biofuels and biopower mandates are achievable with modest and achievable increases in forest production alone in most regions.
Region 6 is probably too small and isolated to be considered independently.
How Achievable is a Doubling of Forest Productivity?
CAPAG Forest Management Option
Goal: by 2020 double the productivity of 50% of NC timberland for high value products and claim these products and energy as carbon offsets.
Enhance funding of the Forest Development Program (NC DENR)
~$230 million for 10 years
Discounted cost of about $260/acre in program
10% of the budget reserved for forestry extension
Forest Industry Health
Financial motivation for forest landowners is not to produce biomass product,
Motivation is to produce a high value solid wood product , biomass is a co-product (so is pulpwood).
Forest residue energy relies on health of the solid wood product market