Understanding the Value of Woody Biomass in Helping Meet the EverGrowing Demand for Energy John R. Shelly, PhD UC Cooperative Extension Forest Products and Woody Biomass Advisor University of California Berkeley presented at: Southern Sierra Community-Scale Bioenergy Workshop Terrace Center, UC Merced October 22, 2013

Woody Biomass • Forest-based, non merchantable trees, shrubs and harvesting residues • Urban Wood Waste stream – Construction and demolition wood – Post-consumer use wood products – Tree removals and trimmings

• Wood Manufacturing Residue • Chaparral • Agricultural Residues – orchard removals and prunning

Characteristics and Cost Factors of Various Types of Biomass • Landfill Diversion – cost of sorting out unacceptable materials and grinding is offset by tipping fees

• Sawmill Residue – clean sawdust, wood, and

bark…costs offset by lumber manufacturing; can be used as raw material for value-added products

• Logging Residue – collection, grinding or chipping costs are offset by timber value

• Agricultural Residue – costs offset by crop value • Forest/Fuel Reduction Thinning or Salvage – costs covered by the value of the biomass produced???

John Shelly, UC Berkeley Cooperative Extension

Forest-Based Woody Biomass • Positive Attributes – carbon source – provide beneficial habitat – restoration and watershed protection – potential raw material ??

• Negative Attributes (too much of a good thing!)

– retard tree growth – habitat for destructive insects and tree disease – wildfire fuel – disposal problem

California Biomass 2007 40 Total (million BDT/yr)

35

Gross Potential Technically available

Million BDT/yr

30

83 32.4

25 20 15 10 5 0 Agriculture

Municipal waste Logging/Slash Forest thinnings

Sawmill Residues

Chaparral

Incentives for Biomass Utilization • Reduce Fire Hazard, especially in: • Overstocked Stands • Urban-Wildland Interface

• More Efficient Use of our Renewable Natural Resource • Decrease Reliance on Fossil Fuels • Reduce landfill disposal • Improve Air Quality (more favorable emission profile than fossil fuels)

Woody Biomass is a Low Value, Low Quality Raw Material? • Wood Quality – High bark/fiber ratio – knots – juvenile wood

• Species Specific Products but Woody Biomass is Typically Mixed-Species • High Processing Cost • Competing Feedstocks

Inferior Wood Zones

juvenile zone

reaction wood in branches

Juvenile Wood - the first 10 to 20 years of growth at any given height of the tree…forms a cylinder zone the whole length of the tree Knots – portion of branches embedded in main bole of tree

knots

best wood

Reaction Wood – wood zones formed in reaction to the gravitational pull on branches or leaning trees • compression wood in softwood species • tension wood in hardwood species

Barriers to Increasing Biomass Use for Electricity Production • Low density fuel with high costs of collection and transport • Emissions • Grid Interconnect • Fuel Availability

Biochemical Potential Softwoods

Hardwoods

40-44 %

43-47 %

Hemicellulose

25-29

25-35

Lignin

25-31

16-24

Extractives

1-5

2-8

Ash

<1

<1

Cellulose

15,000 BTU Torrefied Pellets 48 lbs/ft3 25

40 lb/ft

lb/ft

55 lb/ft 13 lb/ft

What can we Do with Biomass? Grind it

John Shelly, UC Berkeley Cooperative Extension Denver

Presented, Bioenery Conf. 3MAR06 at

What can we Do with Biomass? Grind it

Chip it

John Shelly, UC Berkeley Cooperative Extension Denver

Presented, Bioenery Conf. 3MAR06 at

What can we Do with Biomass? Chip it

Grind it

Burn it

John Shelly, UC Berkeley Cooperative Extension Denver

Presented, Bioenery Conf. 3MAR06 at

What can we Do with Biomass? Chip it

Grind it

Burn it

Convert to fuels and other Organic Chemicals Wood = C + O + H

John Shelly, UC Berkeley Cooperative Extension Denver

Presented, Bioenery Conf. 3MAR06 at

Feedstock Preparation for Higher Value Products – bark and dirt removal, breaking wood down into uniform sized particles, desired moisture content Increases surface area – needed step for most chemical or biological processing

Minimizes the impact of inherent property defects (knots, juvenile wood, etc.)

John Shelly, UC Berkeley Cooperative Extension

Potential Products for Biomass Most Likely • Firewood/Fuelwood, Combustion Fuel Chips, Fuel Pellets • Soil Additives/Amendments

• Liquid and Gaseous Fuels: alcohol, producer gas, syngas, etc. Pulp Chips • Other Organic Chemicals

Unlikely • Solid Wood Products • Composite Panels • Fiber/Plastic Composites

Life Cycle Inventory and Economic Analysis Raw Material E/$

E/$ E/$ E/$ E/$ E/$

Harvest Collection

Emissions

Transportation Feedstock Prep. Process Residue handling

Product Residue

Quadrillion BTU

US Energy Demand 100 95 90 85 80 75 70 65 60 55 50 1970 1980 1990 2000 2010 2020 2030 2040 Year Source: Energy Information Administration: Annual Energy Outlook 2007

Global Carbon Cycle (billion metric tons)

+ 3.2 Billion tons per year to atmosphere 88

6.3

90 119

120

Oceans

Caused by human activity Vegetation and Soils

California Electricity Generation - 2012 Solar & Wind 6%

Nuclear 9%

(1.9%)

(19%)

Geothermal 6% (5.9%)

Hydro 14%

Coal 1%

(18.4%)

(16.1%)

Oil 0%

Biomass 3%

(0.0%)

(2.5%)

Natural Gas 61%

(values in parenthesis are year 1999) Solar & Wind

Geothermal

(37.4%)

Coal

Oil

Natural Gas

Biomass

Hydro

Total Generation = 302,072 GWh (226,306 GWh, 33% increase ) Biomass Generation = 6,031 GWh (5,663 GWh, 6% increase)

Nuclear

Source: CA Energy Commission

California Biomass Energy Facilities Sawmill Cogen Other Biomass Power Plants

30 + MW 20 - 30 MW 10 - 20 MW 0 - 10 MW

27 facilities with total capacity of about 626 MW using 4.5 million bone dry tons of biomass per year • 22% forest-based • 29 % manuf. residue • 28% landfill diverted • 21% ag residue

A 10 MW (megawatt) generator can supply electricity to about 10,000 homes.

The 7 cogeneration facilities are co-located with sawmills

About 15% of total biomass available and about 12% of forest-based biomass available

Power Plant Efficiency Natural gas combinedcycle Coal-fired steam/electricity Biomass-fired steam/electricity Biomass-fired, combined heat and power (co-gen)

Heat Rate (Btu/kWh) 7,500

Efficiency (%) 45.5

10,000

34.1

15,000

22.7

8,500

70.0

The case for Combined Heat and Power Influence of Heat sales on COE Assumptions: • • •

0.15

$5000/kW capital cost Fuel cost ~$40/dry ton 70% overall energy efficiency – –

COE ($/kWh)

0.1

•

23% fuel-to-electricity efficiency 47% fuel-to-heat recovery efficiency

Value of heat = $8/million BTU –

Based on industrial heat produced from natural gas

0.05

Cost of Electricity ($.12) in Biomass power plant Cost of Electricity ($.15) in CHP plant with no heat use Cost of Electricity ($.09) in CHP with heat valued at 8$/MM BTU

0 0

2

4 6 Value of Heat ($/MMBtu)

8

10

Source: http://tonto.eia.doe.gov/dnav/ng/hist/n3035ca3m.htm

Conversion Pathways Thermochemical Combustion

Thermochemical • Pyrolysis • Gasification

Heat Electricity Heat Electricity Bio-diesel Alcohol Organic chemicals

Biochemical • Anaerobic digestion • Hydrolysis/Fermentation

Alcohol Organic chemicals

Physiochemical • Heat/Pressure/Catalysts

Organic chemicals

Combustion – A Basic Thermal Technology Biomass Fuel Excess Air

CO2 + H2O

Combustion Heat

Ash

Boiler Emissions • CO • Nox • SOx • others

Steam, Heat

Electricity or CHP

Typical Biomass-Fired Powerplant 4 month supply of biomass fuel

• 20

Air Emissions Cleanup

Boiler and Generator

MW capacity • Processes 150 - 180 thousand BDTons/yr (~1BDT/MW/hour) • Biomass transported up to 50 miles • Delivered biomass valued at $20 - 55 per BDT • Average production cost ~ $0.08 - $0.10/kWh • Installed cost = $3,000 - $5,000 per kW

Basic Pyrolysis Technology • Thermal decomposition of biomass at (400 – 900 °F) with little or no air (oxygen). • Products of thermal decomposition are char, tar, and Pyrolysis gas (methane), torrefied biomass • Controlling temperature and residence time products produced. Low temperatures favor char production, higher temperatures favor tar and gas products.

Pyrolysis

Char (biochar)

tar

Pyrolysis gas

Torrefied Biomass

Soil amendment ? Upgrade to bio-oil? Fuel for Combustion or gasification

Basic Gasification Technology Air = higher N2, lower BTU; O2 = low N2, higher BTU; steam = high H2, highest BTU Fuel (woody biomass) Gasification

Heat

Oxidant (air or oxygen)

Product Gas CO,CO2, H2, N2, H2O, hydrocarbon gases

Tar, Particulates, H2S, NH3

Boiler

Steam, Heat

Engine Gas Turbine

Electricity or CHP

Fuel Cell

Syngas

Liquid Fuels

Char + Ash

Gasification = High temperature (> 1200 oF), partial oxidation (limited air or oxygen) of organic materials produce a combustible, low BTU fuel product gas (100 – 400 btu/ft3); compare to natural gas at 1,000 btu/ft3. The product gas can be refined to syngas, a precursor to higher value products.

Biomass Combustion Concerns • Availability and cost of Fuel • Emissions – a complicated story • Higher maintenance compared to other fuel types can lead to reduced capacity and efficiency – Inorganic (ash) transformations lead to fouling of combustion chamber surfaces and slag formation on bottom – Increased corrosion from acidic gases

• Grid Interconnect challenges

Combustion PROS • Simple process to produce heat • Gaseous emissions are similar to those of the natural decomposition of wood

CONS • Particulate emissions may not meet clean air requirements • Low efficiency unless CHP • Strict boiler operation requirements

Pyrolysis PROS • Can produce hydrocarbon gases, liquids, and a solid char product (e.g. charcoal) • Solid char has properties similar to that of coal and can be used to co-fire coal combustion units • Relatively low costs

CONS • Bio-oils have a high moisture content and a complex mix of organic chemicals and are not very compatible with other fuel oils • Markets for products are untested

Gasification PROS • Produces a versatile fuel gas that can be: – used directly or stored – combusted to produce heat – Used to synthesize other chemicals

• Lower emissions than combustion • Char ash may have value as carbon source or soil amendment

• • •

•

CONS Lower BTU value than natural gas or LPG High production costs (capital and operating) Tar contaminates the gas and must be cleaned for higher value uses Char ash may be a disposal problem

Encouraging Biomass Utilization 1. 2. 3. 4. 5. 6. 7.

Reduce handling and processing costs Improve conventional technology Improve conversion efficiency Develop new processes Develop new products Develop new markets Educate public to benefits of utilization

Trees for the most part grow without intensive cultivation and are more adaptable to environmental changes than most plants. They consume CO2 and produce wood – a basic building block for many products.

The importance of woody biomass as a raw material will increase dramatically through the 21st century becoming the raw material of choice for many carbon-based materials.