Biomass in Electricity Generation Richard Lee HAWKINS WRIGHT
Content Who am I? The UK electricity market The market for biomass power The economics of biomass power Biomass supply chains Torrefied fuel Embodied carbon are we saving CO 2?
Who am I? Brief History... > Graduate of Sheffield University Electrical Engineering 1990 > Various engineering/management roles with ICI and Zeneca nearly all utilities based Coal, oil and gas fired combined heat and power > Consultant with specialist CHP design and build company gas then biomass with Finnish energy company > Government and Regulatory roles in Australia > Setup and ran regional renewable energy support organisation Future Energy Yorkshire > Director of Biomass and Generation for Cleantech investor > Director of Bio-energy for Forest Products Trading Company > Energy and Sustainability Consulting - own business
The UK Electricity Market Energy Flows Generation Transmission + SHETL & SPT Distribution Consumption DUKES
The UK Electricity Market Money Flows Generation Balancing Market Transmission Contracts /Markets Distribution Supplier Consumption
Electricity Market Regulation There is a competitive market in electricity > But it is highly regulated Investment decisions are driven by: > Cost of fuel Note that pelletised biomass is 2-3 times the cost of coal on an energy basis > Cost of plant capital and operational > Technology risk > Political risk EU Emissions Trading Scheme EU Directives on other emissions (IED) Renewables Obligation Climate Change Levy and Carbon Floor Price
The Market for Biomass Power HAWKINS WRIGHT
Where can we use biomass? Dedicated new-build power plants or CHP > Sub 10MW Gasification? Organic rankine cycle? > 10-300MW per unit conventional steam cycle Coal station conversions > Typically 500MW units (Drax = 660MW units) > Typically 1000-4000MW per station Alternative markets > Heating fuels > Second generation bio-fuels > Chemicals oil substitute
What is the potential for biomass power? 1 GW dedicated power = 6.5M green tonnes per year About 10GW of existing coal capacity is currently in the planning stages of conversion > 40-50M green tonnes per year (depends on utilisation) > Will be supplied as pellet: 20Mt per year + > Current UK demand about 3Mt per year Heat demand could be several million tonnes
Does that seem like a lot? 70M green tonnes
Biomass Power Economics HAWKINS WRIGHT
The Renewables Obligation ROCs Number of ROCs per MWh of Power Supplied ROCs SUPPLIER Supplier Obligation ROCs 41/MWh Buyout Payment Buyout Recycle in proportion to % obligation achieved
Electricity Market Review New electricity/energy act will: > Replace ROCs with a complex Contract for Difference feed-intariff Most biomass power likely to built under ROC regime other than future CHP > Set a cap on the emissions that can be generated by power plant effectively rules out new coal without CCS > Establish a capacity mechanism > EMR also included the Carbon Floor Price, but already implemented in legislation
Forecast wholesale power cost Effect of carbon floor price
Incentives for biomass in power generation Coal co-firing and conversion ROCs: 0.3 to 1 per MWh EU-ETS about 8/t CO2 Carbon Floor Price > From April 2013 > Total cost of carbon (inc. ETS) rises from c 19/tCO2 to 34/tCO2 in 2020 and 74/t in 2030 Industrial emissions directive > Biomass will make compliance easier and cheaper New build ROCs: > 1.5 ROCs / MWh > 2 ROCs/MWh CHP ETS/ Carbon Floor Price does not directly impact but should push up wholesale power prices. But Government has set a 1GW cap on non-chp new-build above 1MWe
Co-firing (Coal Conversion) Economics ROC Bands
Short-Run Coal Station Economics 10% co-firing (no CAPEX required)
Short-Run Coal Station Economics 50% co-firing (CAPEX required)
Short-Run Coal Station Economics 95% co-firing (CAPEX required)
Long-Run Coal Station Economics 2000MW station conversion options
Coal Station Economics 50% co-firing breakdown Political risk!
New-build Economics A few words on efficiencies. There is no standard way of quoting power plant efficiency! Plant Type Fuel Moisture Net Efficiency Net Efficiency Gross Gross at Generator at Grid Export Efficiency at Efficiency at Generator Grid Export 50MW Pellet 10% 33.42% 30.76% 36.23% 33.35% 50MW Chip 40% 31.01% 28.54% 300MW Pellet 10% 36.20% 34.39% 39.25% 37.28% 300MW Chip 40% 33.59% 31.91%
New-build Economics Simple cycle wood-chip fired plant
New-build Economics Sensitivity to fuel cost (chip plant)
CHP Plants They re all different! > Different capital costs > Different heat profiles > Different heat utilisations Very difficult to generalise! The proposed RHI tariff for CHP heat looks attractive 4.1p/kWh is more than the cost of gas!
Biomass Supply Chains & Torrefied Fuels HAWKINS WRIGHT
Biomass forms and treatments Biomass as a solid fuel Three main sources: > Woody biomass Residues from forestry Energy plantation such as eucalyptus > Non-woody energy crops Myscanthus / Elephant grass Reed Canary Grass > Agri-residues Corn stover Rice husk Palm residues Forms Round wood, chip, pellets, torrefied Bales, pellets, torrefied Bales, pellets, torrefied
Biomass forms and treatments Alternative treatments The waterproof pellet > Coating or binders which enable the pellet to be stored outdoors > Source/content of coatings and binders are critical > Gains some logistics advantage > Maybe issues with friability Steam explosion > Offer many of the advantages of torrefaction > CV typically not quite as high > Can reduce ash content and remove alkali metals > Process economics? Hydrothermal treatment > Can produce product similar to torrefied > Can reduce ash content and remove alkali metals > Process economics?
Biomass forms and treatments Torrefied fuel principles MASS BALANCE ENERGY BALANCE DRYING AND TORREFACTION PROCESS 75% of DRY MASS 90% of ENERGY Torrefied Product Energy Densification: 90%/75% = 1.1-1.2 Densification is essential for transport Dry Net CV Enhanced from circa 19GJ/t to 21-23GJ/t
Biomass forms and treatments Property Comparisons Property Woodchip Wood Pellet Torrefied Fuel API Coal Calorific Value (GJ/t Net AR) 11.4 17.10 22.00 25.00 Moisture (%) 40% 10% 3% 12-15% Bulk Density (kg/m3) 350 650 750 800 Energy Bulk Density (GJ/m3) 4.0 11.12 16.50 20.00 Hydroscopic Nature Wets, outdoor storage Wets, must be stored dry Hydrophobic, outdoor storage Hydrophobic, outdoor storage Storage Behaviour Spontaneous combustion, dry matter loss, mould Some mould, generally good if kept in dry, controlled conditions. Stable, dependent on pellet/ briquette performance Stable Volatile Matter (%) 80%+ 80%+ 70-80% 22-37% Sulphur Content (%wt Dry) <0.5%, typically around 0.1% for woody biomass <1% Ash Content (%wt Dry) <7% (With bark) <3% <4% 11-15%
New Fuels The challenge for developers All I need is $50M of risk money to build a plant to make the trial volume. Look at our fantastic product it s just what you need to produce green power without spending capital. It certainly looks interesting. I ll have a million tonnes when you ve supplied a 5,000t trial that ll be a one day test.
Biomass forms and treatments Torrefied fuel No large scale production Several first large scale plants are in commissioning/early operation Several thousand tonnes have been supplied to utilities Combustion trials appear to have been successful No standards developed Final product packaging uncertain > Pellet vs briquette
Biomass Logistics Source fibre cost typically <20% of delivered fuel cost Chip Logistics costs typically >50% of delivered fuel cost Getting the logistics right is key to delivering cost effective fuel White Pellet
Biomass logistics It s all about energy density Front loader bucket is about 5m 3 > Each bucket contains: 20GJ of chip energy 56GJ of pellet energy 83GJ of torrefied fuel energy Multiply this up for: > Vessel grabs > Trucks (weight constrained) > Rail wagons > Ships Storages can also be smaller > Need to replicate coal! 15m high, 60m base width 38 angle of repose 612m 3 per m length 30 angle of repose 510m 3 per m length
Supply chain economics US SE Example Cost per tonne Cost per GJ Logistics Cost In the long term torrefied fuel could be 1/GJ cheaper to deliver
Supply chain economics Fibre processing Economically optimum point of torrefaction > Across whole supply chain > Often auto-thermal point > Depends on feedstock cost Need to consider properties of torrefied material > Generally ok at this point Product bulk density and equilibrium moisture content are also key unknown factors
Supply chain economics Logistics costs Shipping Torrefied fuel is less sensitive to main shipping cost variables > About 25% less sensitive than white pellet Very large swings in charter rates are possible, so reduced sensitivity is valuable for voyage charters. Port Operations Biomass is a challenge due to distributed nature of resource Torrefied fuel should have significantly lower storage and handling costs: Open storage More basic handling Much lower capital investment
The value of torrefied fuel Potential savings of 1/GJ on delivered energy cost > High risk torrefaction developers will want a share (all?) of this Additional benefits for end users are: > Significantly lower handling and storage costs > Lower plant conversion costs due to improved friability and more coal-like properties > Low capital investment for conversions that may have a short life > May provide a cheap way to extend the life of existing plant and also help meet IED emissions limits > Some operational savings over white pellet All these could be worth another 0.5-3/GJ on the fuel value A capacity benefit.
The value of torrefied fuel Capacity benefits White pellet reduces plant capacity > Partly due to energy density/volume constraints > Tilbury: 1100MW 750MW Torrefied fuel, assuming sufficiently coal-like, may overcome a significant proportion of this issue A 500MWe unit burning torrefied fuel at 60% utilisation could produce an extra 328,000MWh per annum cf white pellet > Value is circa 5.8M per annum at typical green power values The value of this additional premium is about 0.55/GJ on a fuel input basis
Embodied Carbon and CO 2 Savings HAWKINS WRIGHT
Is biomass renewable? The theory is simple but: > Carbon debt > Direct land use change > Indirect land-use change > Sustainability / regrowth > Processing / transport emissions > Generating efficiency > Displaced fuels CO2 emitted in combustion CO2 absorbed by growing plant All these are supply chain specific you cannot easily generalise CO2 emitted in processing and transport
Carbon debt In very broad terms. Extracting biomass from a previously unmanaged forest can reduce the forest s carbon stock resulting in a carbon debt. At the landscape level, biomass extracted from a sustainably managed forest plantation may have a negligible impact on the plantation s carbon stock; carbon emitted during biomass combustion is almost immediately reabsorbed by growing trees, often within a single season. Using sawmill residues can result in an instant carbon credit, especially if residues would otherwise be landfilled or incinerated.
Land Use Change Direct What was the land on which the energy plantation is growing previously used for? Did it store more carbon in that form? > E.g. peat / wet land? Indirect Has the establishment of this energy plantation displaced another activity? > E.g. growing corn/maize for bio-fuels might mean that high-carbon stock land elsewhere in the world is cleared for food crop maize.
Sustainability Is there a programme in place to ensure that the energy crop/wood source is sustainable? Is the extraction process adequately controlled to prevent carbon loss through soil erosion etc.? Is the extraction process controlled to prevent other environmental degradation, excess loss of habitat etc. etc.? Is the forest allowed to naturally regenerate and will it do so at a rate equal to or greater than the extraction rate (over the landscape in question)? Is the forest re-planted? > If so, is it replanted at a rate at least equal to the extraction rate? > If so, are fertilisers or other embodied carbon products used? > Could water courses be contaminated? > Could excess water use be detrimental?
Supply chain CO2 emissions Does not include land use change or silviculture! US SE - Europe US East Coast to Europe Electricity in processing usually dominates > Except where significant hydro e.g. British Columbia/Brazil > Or very long shipping distances Torrefied fuel offers advantages over other forms > Processing emissions per unit energy generally lower due to lower grinding power > Shipping emissions lower South Africa - Europe Canada West Coast to Europe
Emissions at point of use Generating efficiency Assume fuel @ 15kgCO 2 e/gj > =54kgCO2e/MWhth Burn in: 300MW station @ 38% eff. > 142kgCO2e/MWhe 50MW station @ 33% eff. > 164kgCO2e/MWhe 5 MW station @ 20% eff. > 270kgCO2e/MWhe Displaced fuels UK grid average emissions > Circa 500kgCO2e/MWhe and falling Typical coal emissions: > Circa 850kgCO2e/MWhe Typical gas emissions: > Circa 375kgCO2e/MWhe But what if a co-firing incentive encourages more coal firing in the national mix?
Biomass in Power Generation Conclusions There is a big role for biomass in the medium term > A quick win to reduce emissions from coal stations > A few opportunities for dedicated plants > More opportunities for biomass CHP as existing gas CHP retires > Potential biomass demand is many millions of tonnes There are opportunities for new biomass technologies > Pre-treatments to improve properties and reduce logistics costs > New gasification/pyrolysis technologies to enable smaller scale projects Sustainability and evaluation of true carbon cost is key > Must not loose sight of why we want to burn biomass > If it doesn t reduce atmospheric carbon then it isn t worth doing
Air / Oxygen 1Te 40% Moisture, 2% Ash Biomass 21GJ/t HHV Dry Ash Free Basis 580kg Dry Biomass Energy = 21 x (1-40%) x (1-2%) =12.35GJ HHV 20kg Ash Combustion Process Energy Release from [C + O 2 CO 2 ] + [2H + ½ O 2 H 2 O] 12.35GJ/t HHV As Received Carbon Dioxide Circa 1100kg Circa 325kg Liquid Water 400kg Liquid Water 11.65GJ/t LHV As Received 10.65GJ/t LHV As Received Recoverable 0.7GJ 1.0GJ Vapourise Vapourise Water Vapour