Biomass Pyrolysis for energy, fuels and char in the WA Wheat Belt

Ben RoseEnvironmental Consultant

Contributing author: “The Biochar Revolution” www.TheBiocharRevolution.com

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Four-row Oil Mallee Plantings on Annual Pasture Land

Planting Mallee with Small Tractor-mounted Planter

Hydrology benefits – oil mallees can lower saline water tables

Nominal root extension 12- 13 m; Nominal belt width 10 m

root depth up to 10 m 13 m excluded from cropping

Growers within a “cell” of about 50 km radius

Capital expenditure of about $1,500 per ha is required to establish the trees.

This could be incurred by farmers who wish to fund their own mallee plantations,

or by carbon off-set organizations in return for carbon rights,

or by industry or government, which could pay an annuity of $50-100/ha or a standing-biomass price of about $40 per dry ton should be viable

(Such annuities are already paid by woodchip companies to hundreds of farmers with blue gum plantations)

7-year old saplings. Foreground: first coppice less than 12 months old

ITEM GROSS MARGIN FOR OIL MALLEE BIOMASS

GROSS MARGIN FOR WHEAT (www.dpi.nsw.gov.au, 2010)

Average Yield (dry tons per hectare / year)

2.6 1.7

Price (A$ per dry ton) delivered to plant or bin

$80 $240

Transport and Handling Costs (per ton)

$20 $35

On farm price per ton dry product (post harvest)

$60 $205*

Harvest cost per hectare/year $50 $60

Other variable costs per hectare / year (including sowing-planting, fertilizer and chemical inputs, harvest, insurance)

$30 $155

GROSS MARGIN (APPROX A$ per ha) $76 $134

GROSS MARGIN with establishment costs (A$30) offset by sale of on-site C**

$106

Harvester cuts trees at ground level, chops biomass to size, and conveys it to windrows or directly into mobile hoppers. (Photo: courtesy John Bartle)

Energy Balance of Mallee Biomass Production in Western Australia

Hongwei Wu1, Qiang Fu1, Rick Giles2, John Bartle21 Department of Chemical Engineering, Curtin University of Technology, GPO Box U1987, Perth WA

Estimates that oil mallee production has energy ouput: energy input ratio of 41.7

Inputs are primarily fuel for harvest and transport, fertilisers

Saran Sohi1, Elisa Lopez-Capel2, Evelyn Krull3 and Roland Bol4. CSIRO Land and Water Science Report 05/09; February 2009Biochar, climate change and soil: A review to guide future research

heating at low to medium temperatures (450 to 650°C)

CHAR PRODUCTION + ENERGY

Estimates based on conservative assumptions: •10% of wheat belt 4m ha under coppicing woody biomass crops •Plantations are in belts or blocks of >10 m crown width. •Dry biomass production averages 2.6 t/ha/year.

Reduces CO2e in 4 ways:

1. displacing coal-fired electricity by biomass energy 8.5 m tons

plus 2. carbon sequestration by roots, tubers, and soil 6 m tonsplus3. application of biochar to soils (potential) 5.1 m tonsplus4. Less Me emissions, displaces 8m sheep equiv. 1.4 m tons

TOTAL emissions avoided or removed 20 million tons

That is 3.6% of Australia’s total emissions of 576 million tons, or 24% of Australia’s agricultural emissions of 88 million tons. 7

Pyrolysis of biomass to produce bio-char can result in a net removal of CO2 from the atmosphere

Table 18.5 below illustrates how: • a RECs price of $38 per ton

plus • a carbon price of $30 per ton,

and• a biochar price in excess of $240/ton

could make the viability of biomass power generation comparable to coal, at generation costs of $170 per MWh for pyrolysis respectively.

COAL

COMBUSTION POWER STATION

BIOMASS COMBUSTION

POWER STATION

BIOMASS PYROLYSIS

GAS POWER STATION*

% of feedstock energy used in power station 100% 100% 50%

Carbon emissions tCO2e/MWh (Gaunt and Lehmann, 2007) 1.0 0.1 0.15

Turbine type/efficiency Steam cycle 30% Steam cycle 30% efficient

Gas turbine, 35%

Biochar production, tons per MWh 0 0 0.22

Electricity generation cost, A$/MWh $50 $115 $168

Minus RECs rebate at A$38/MWh $50 $77 $130

Plus cost of CO2 emitted at A$30/t $80 $80 $135

Minus value of biochar at $240/t = Sales price of electricity $80 $80 $80

Mallee Biomass Energy and Yields

Dry biomass energy content 19.5 GJ/t

Dry biomass energy content 5.4 MWh/t

Assumed average dry biomass yield, mallee belts, 300-500 mm rainfall 2.6 t/ha

Western Australia

Dry biomass from 10% of WA grain belt (0.1*14m/ha * 2.6t / ha/ yr ) 3,640,000 tons/yr

Annual energy content of mallee biomass 19,717 GWh

Energy from pyrolysis syngas and bio-oils (50% of energy) 9,858 GWh

Annual electricity generated @ (0.95 MWh/dry ton, Table 18.3) 3,450 GWh

Total annual generation WA South West Grid 20,679 GWh

Oil mallee belts – potential % of above 16.7%

Australia

Dry biomass from 10% of Australian dry land grain belt (0.1*40m ha * 2.6t /

ha/ yr) 10,400,000 tons/yr

Annual energy content of mallee biomass 56,333 GWh

Energy from pyrolysis syngas (50% of total) 28,167 GWh

Annual electricity generated @ 35% efficiency 9,858 GWh

Percent of total Australia generation (230,000 GWh in 2007) 4.3%

Biochar production @ 22% of dry biomass 2,228,000 tons/yr

CO2e emissions reduction by displacement of coal @ 0.85 t/MWh 8,379,300 t CO2e /yr

Biochar CO2e sequestration potential @ 2.3 tCO2e per ton biochar 5,124,400 t CO2e /yr

Onsite CO2e sequestration potential – roots and tubers of mallee trees: 4

million ha @ 1.5 t CO2e / ha / yr

6,000,000

t CO2e /yr

Methane emission avoided by displacing 8 million sheep @ 0.17 tCO2e/hd 9 1,360,000 t CO2e /yr

http://www.renoil.com.au/about.html

….working towards the construction and operation of its first commercial scale pyrolysis plant in Australia……200 tonne per day pyrolysis plant using wood waste as feed.

Similar plant in Canada shown below

BIO-OIL

fine particle size of <2mm permits rapid transference of energy despite relatively moderate peak temperatures of around 450°C (and in the range 350 to 500°C).

“Bio-oil is condensed from the syngas stream under rapid cooling, with the combustion of syngas providing the pyrolysis process heat. The bio-oil is a low grade product with a calorific value, on a volume basis, approximately 55% that of regular diesel fuel. It is unsuitable as a mainstream liquid transport fuel even after refining, and is most suitable as a fuel-oil substitute.”

100% of the feedstock is utilized in the process to produce BioOil and char.

Non-condensable gases are used as energy to run the process, nothing is wasted and no waste is produced.

Three products are produced: BioOil (60-75% by weight), char (15-20% wt.) and non-condensable gases (10-20% wt.)

Yields vary depending on the feedstock composition. BioOil and char are commercial products

The uncondensed, flammable gases are re-circulated to fuel approximately 75% of the energy needed by the pyrolysis process.

Gasification – higher temperature several hundred deg. C. Wood is completely gasified – syngas – hydrogen and carbon monoxide

TRI – GENERATION

• Would be the most efficient use of pyrolysis gas.

• Convert syngas(SNG) to methane (CH4); Methanation Chemistry: http://www.netl.doe.gov/technologies/coalpower/gasification/gasifipedia/5-support/5-12_methanation.html

• Conventional SNG production is based on a methanation process, which converts carbon oxides and hydrogen in syngas to methane and water by the following reactions:

• CO + 3 H2 → CH4 + H2O ΔH = -210 kJ/mol • CO2 + 4 H2 → CH4 + 2 H2O ΔH = -113.6 kJ/mol

• The reactions take place over nickel catalysts in fixed-bed reactors. The reactions are highly exothermic, thus a key challenge for the process is to manage the heat of reaction

• Pipe to city areas of intensive residential commercial or industry.

• Run gas engines

• Use the waste heat to run air conditioning and heating

• Up to 80% efficient

• Being done in Sydney

• Already done in the borough of Woking, UK, 100,000 population; now ‘off grid’ (Alan Jones)

TRI-GENERATION (cont.)

• Inject into existing gas pipe lines. Pipe the ‘bio-methane’ to city areas of intensive residential commercial or industry

• Run gas engines for electricity generation and use the waste heat to run air conditioning and heating; up to 80% efficient

• Being done in Sydney; already done in the borough of Woking UK, 100,000 population; now ‘off grid’ (Alan Jones)