Agriculture related bio-energy production in Wales Dr Rebecca Heaton Senior Renewable Energy Consultant www.adas.co.uk
Dedicated energy crops - what are they? The UK Department of Environment Food and Rural Affairs has defined energy crops as primarily being Short Rotation Willow coppice (Salix spp) and Miscanthus (an energy grass). There is a planting grant available for planting these crops in England (but not Wales) if an energy end use can be proven.
Co-firing - a key driver for energy crops? Biomass mixed in small proportions with coal to reduce CO 2 emissions from large coalfired power stations 10% co-firing with biomass, >75% of which from energy crops by 2006 This will end by 2016 in favour of dedicated biomass plants so reduces stability of market
Energy crops where are we? Fifteen years of research on both crops, funded by UK government Mostly in the arable areas of the UK not Wales Research covered growing, yield, harvesting, transport, storage, fuel supply chains, life cycle analysis, environmental impacts (soil, wildlife, landscape) Both crops being grown commercially in England. Approx. 800 ha Miscanthus, 1500 ha SRC
Monitoring the Fuel Supply Chain DTI Report FES B/U1/00626/00/REP Available at : http://www.dti.gov.uk/renewables/publications_pdfs/bu1006260000.pdf
Benefit of energy crops under Single Farm Payment You can grow energy crop on set-aside and still get payment under the new single payment scheme If you grow on non set-aside you will receive payment under new single payment scheme plus 45 energy crop payment
Miscanthus Perennial high yielding rhizomatous C4 grass Low moisture and nutrient content at harvest 16% mc Easy for farmers to grow and power station to use as a baled product No fertiliser required on most sites Herbicides in first two years essential High yields (15 odt/ha/yr) Harvest using conventional baling machinery
Rhizomes
August - yr 1
May
August yr2+
February
Potential yield of Miscanthus Potential Yield (tonnes / ha) 5-10 10-15 15-20 20-25 > 25 N 0 100 200 Kilometers
Short rotation willow coppice Specifically-bred varieties of willow, harvested every 3 years Plantations viable for up to 30 years Specialist machinery required for planting, cutback and harvest Well-prepared land should produce 7-12odt/ha/yr IGER (Institute of Grassland Ecological Research) in Aberystwyth trialling new high yielding varieties
Ground preparation Create weed free seed bed by applying herbicide Plough and harrow to produce fine tilth
Applying slurry to coppiced stools
Mechanised planting
Two months after planting
Nutrition (1) No N in planting year (OM maybe) Low demand for N because of : nutrient re-cycling with leaves atmospheric deposition soil mineralisation Annual applications between 40 and 100kg/ha N
Nutrition (2) Code of Good Practice for water no more than 250 kg/ha total N in any 12 month period and no more than crop requires N application should be a balance between: crop offtake per ODT (6kgN,2kgP,4kgK) N leaching N volatilisation and de-nitrification (warm & wet)
Yield Expectation - 12 t/ha/yr Reality at the moment - 7 t/ha/yr Breeding and improved agronomy advice should increase yields Site selection - never the best sites!
Pest and disease Rusts Melampsora serious problem in willow Control strategies through plant breeding and polyclonal stands Pests Chrysomalid beetle most common pest in willow Most pests site specific at present
Willow rust (Melampsora epitea) Significant yield reductions Death of susceptible willow varieties Increasing susceptibility of varieties over time
Other species Switch grass Reed Canary Grass Reduced risk, as low establishment costs ( 160 a hectare for seed) Straw an option, from bioethanol processing
Birch trial age 13 yr (thinned at age 5 yr) HRI East Malling, Kent
Which energy crop? Miscanthus: SRC: Machinery available Low mc at harvest BUT may not be burnt in all end-uses High yielding on good soil Wider range of end uses Requires specialist machinery Difficult to harvest on wet sites
Reasons to grow energy crops Productive and economic use of setaside Long-term crop needing little maintenance Keeps the land in good agricultural conditions Frees up time for other enterprises Diversification/downshifting option under CAP reform Permanent game cover As a physical barrier
Environmental benefits Varying age structure of SRC results in many different habitats for insects, birds, and small mammals Studies on Miscanthus found increased diversity - particularly at field margins On-going research by Cardiff University in mid- Wales to quantify this.
Species diversity - UK Miscanthus compared with rye Miscanthus gives rise to: trebling of earthworm numbers greater numbers and diversity of ground beetles three times more spiders more spider species
Results from Arbre Biomass crops use more water than arable crops. So growing in the wetter west may be the best option, ploughing up grassland rather than arable. BUT we found significant differences in carbon balances for for SRC planted on arable land (strongly positive) and after grass land (-11 tonne/ha) negative. We need to devise a way of band spraying grass land, or even overall spraying that minimises carbon loss.
Energy crops - barriers to planting Energy crops do offer an alternative to forestry, but Expensive! Uncertainties over yield in Wales Specialist equipment Field size can be a problem Case by case assessment needed A combination is likely to be the best option Don t plough up grassland!
Case study (1) - Small scale heat Miscanthus fired heating unit at Kings Langley Poultry farm converted into offices New office development ADAS planted 5 ha of Miscanthus in April 2002 Recommended boiler size (70kW) and manufacturer Crop growing well on challenging soil
Case study (2) - Supply to Ely power plant Fully commercial ADAS supply rhizomes ADAS plant crop Miscanthus straw cut and baled and bought under contract at standard rate 100 hectares planted in 2002 400 hectares planted in 2003/4 8000 tonne a year supply contract Expectation - >500 ha,
Case study (3) - Shotton Paper Mill North Wales: Shotton Paper (part of UPM Kymmene) are installing an 82 MW steam CHP plant Requires 250 000 tonnes of biomass This will 1be sourced from: brash small roundwood Short Rotation Willow Coppice Due to be commissioned in September 2006 New and mature SRC in Wales
Case study (4) - Co-firing in South Wales Innogy (npower): Aberthaw near Barry is cofiring And issuing contracts for wood fuel and SRC Actively sourcing fuel Potential for Miscanthus No comment on size of market
Energy Crops - the positives Benefits to end-user : Long term security of supply Dedicated fuel supply - no competitors Benefits to supplier: Environmental? Socio-economic benefits Alternative to current agriculture