The BiogasAction project is relevant to the whole of the UK but, for practical purposes will concentrate most of its activity in Wales. It will do this largely because the Welsh Government has demonstrated a keenness to engage with the concept of small-scale, on-farm and waste based AD. If a model can be established in Wales there is no particular reason that this could not be extended to England and the remainder of the UK.
In August 2017, there were 18 Anaerobic Digestion (AD) plants in Wales, of which 13 were completed in the previous 4 years. Seven food waste plants exist; and a further eight plants are believed to be in the developmental process. Two of the existing plants process “other waste” (abattoir waste, and the organic fraction of municipal solid and commercial and industrial wastes). The remaining nine AD plants are farm fed.
With the exception of food waste processing plants, the AD industry in Wales is centred upon small to medium scale facilities, and it has been identified that this lower capacity, i.e. farm scale AD, is the area that requires the most support.
Dairy farming, in particular, would be a primary candidate for farm scale AD, as it produces large volumes of manure and slurry and also has relatively high energy use. The dairy farming industry in Wales is centered primarily in South West Wales, in the counties of Pembrokeshire, Carmarthenshire and Ceredigion, and to a lesser degree in some areas of North East Wales. A recent study in 2014 reported there to be 1,853 milk producers in Wales, which showed a 32% decline from 2004 figures. The total number of dairy cows in Wales, however, has only fallen 4% in the past 10 years, with a total number of 234,000 in 2014. The average herd size, therefore, has increased (by 7.4%) to 127 dairy cows. If these were good-sized dairy cows, the slurry from these would equate to an AD plant of approximately 13kWe or equivalent.
UK funding for electricity generation from AD plants (FITs; Feed in Tariffs) and, more recently, for the use of renewable heat and biomethane injection (RHI; Renewable Heat Incentive), has unintentionally tended to favour comparatively large scale systems, due to the way the tariffs are set and structured. Small scale, on farm AD below 500kW capacity has proven to be more difficult to fund due to the relatively high cost of project delivery in comparison to the energy generated. While larger scales of AD offer benefits in terms of cost per kWh of energy, they require secure supplies and larger volumes of feedstock. This has tended to mean that they rely heavily on crop feedstocks in order to be able to manage the financial risk posed by feedstock insecurity; or that they are waste fed. The growing of maize is seen as being particularly disadvantageous in environmental terms and grass would be seen as a better supplement to waste products (if considered essential), and produces a similar gas yield. While small scale AD is higher cost per kW of energy delivered, it can deliver a range of wider benefits to the agri-environment sector which are not currently recognised financially.
Advantages of on-farm Anaerobic Digestion of Animal Wastes
There are many advantages to promoting farm scale AD in Wales. From an environmental perspective, processing slurry through AD enables sustainable nutrient management on farm, and also enables the export of unwanted nutrients from enriched sites to sites lacking in nutrients. AD also enables sustainable soil management, by increasing soil organic matter and water holding capacity. Greenhouse Gas (GHG) emissions are reduced with less storage, handling and spreading of manure, and decreased demand for chemical fertilisers.
There are also several economic advantages of farm scale AD. Dairy farms have high heating and cooling demands and heat generation can be utilised to heat buildings, water for washing down and sterilisation, drinking water for the cattle (which improves health), or to dry timber, and there are currently government incentives (RHI) to do this. Therefore on-farm energy costs are decreased, in addition to reduced slurry management costs and fertiliser costs. Grass growth achieved from digestate application has been shown to parallel that of a compound chemical fertiliser, thus negating the need to purchase fertiliser in many cases. In comparison to direct slurry application, the use of digestate as fertiliser has been shown to increase the growth rate and quality of grass, thus resulting in healthier cattle. Digested slurry is less odorous than the raw material and therefore improves the amenity of the surrounding area. The biological oxygen demand of digestate is far lower than raw slurry and the nutrients are in a form that renders uptake by the plants much easier – the pollution of water courses and groundwater is therefore much less likely with digestate than with raw slurry.
AD can be used as a means of reducing pathogens, parasites and viable weed seeds from slurries and manures, with careful consideration of feedstock retention times and digester temperature. It can subsequently be used as a means of processing infected manure, and of decreasing weed proliferation on farmland, thus reducing associated costs of infection / weed control. A pasteurisation step can be added where necessary, as is already mandatory for digestate arising from food waste.
Barriers to Implementation of Small Scale Anaerobic Digestion
The general perception amongst the stakeholders invited to attend the initial strategy meeting, was that legislation surrounding AD is overly complicated, including waste legislation, movement of slurry regulations, and planning regulations, although these regulations are reduced for a small scale plant using on farm wastes only. The costs and associated risks, as well as high capital costs with inadequate funding, make AD an unattractive proposal for a small scale farmer. Legislative restrictions can also complicate farming cooperatives that might look to pool feedstock into one plant.
Although the dairy farming industry may be the most suitable candidate for AD plant promotion, it is currently unstable due to low prices for milk. Many small dairy farms are being sold, or at least are not currently planning long term developments. The extra workload associated with supplementing a slurry based AD plant with additional feedstock can be difficult to maintain within a small dairy farm.
As there are few on-farm AD plants in Wales, awareness and interest among farming communities is low. Therefore there is a clear need for awareness raising, demonstration events and training events. Sound, independent advice would also be very valuable and this appears to be in short supply at present.
During the first 1 year and half of the BiogasAction project SWEA, the Severn Wye Energy Agency, has been working on different tasks in order to promote and fulfill the targets in BiogasAction and the different challenges in Wales. Several initiatives have been established.
A stakeholder group has been assembled and the first meeting was held in April 2016. The group includes representation from the majority of key stakeholders and several Welsh Government officials. The agency is also in contact with, and have met with, representatives from other stakeholder groups. A sub-group met in June 2017 to specifically discuss the opportunities to the AD industry that might arise from an initiative to promote “vertical farming” in Wales.
The key regional (Welsh) government and local government officials are largely in need of familiarisation with AD – as are many from the regulators such as Natural Resources Wales. To address this the Energy Agency have: made a formal response to the consultation from the UK Government in respect of proposed changes to the Feed-in-Tariff for biogas; input into a Welsh Government strategy for reducing carbon emissions from the agricultural sector; met twice with officers of Natural Resources Wales to discuss the implications of Nitrate Vulnerable Zones on the deployment of AD on dairy farms; met with two LEADER groups in Wales; and taken a Welsh Assembly Member on a tour of a farm biogas plant within her constituency.
The number of biogas plants in the UK has undergone tremendous growth in the past 5 years but that is likely to slow very dramatically under the new and proposed subsidy regimes (Feed-in-Tariff and Renewable Heat Incentive). The growth has been largely at a scale of 250 kW and above and many have utilised energy crops or food waste as their primary feedstock. Through Biogas Action the Energy Agency have worked with key Welsh Government officials to: engage with the AD industry to develop standard products at a scale and cost that is reasonable to deploy on single farms of around 150 dairy cows – without adding in significant quantities of energy crops; and engage with the farming industry to recruit 4 or 5 dairy farms to work with Biogas Action in an attempt to find a viable installation.
The intention is to set Wales (and then England) on a trajectory that sees the digestion of dairy cattle slurry as the norm for good practice. The number of poultry units in Wales has increased dramatically – even since the commencement of the Biogas Action project. The ammonia emissions to the atmosphere from chicken litter are becoming a significant problem – as are the nitrate and phosphate run-off into watercourses. The agency is working with Welsh Government, the Dutch partners and other researches to find solutions for digestion of chicken litter in AD plants. A further area of activity relates to small beef herds and sheep flocks on upland sites with thin soils and increased run off. Biogas Action, the Snowdonia National Park Authority, University of South Wales and National Trust are producing a viability report to consider inexpensive options for digesting solid manure and waste vegetation (such as rush, Juncus sp.) via batch systems.
The current support regime for biogas is wholly based upon subsidising the energy produced; with any capital support from public sources debarring payment of these production incentives. There is a strong case for challenging this rule (derived from State Aid Regulations), for agricultural slurry based systems, because the digester can easily be argued as being “environmental” equipment. SWEA (Biogas Action) responded to a consultation from the UK Government to make the case that only the energy generator itself (boiler or CHP engine) should be debarred from receiving state aid. Biogas Action has addressed a meeting of Barclays Bank agricultural advisors to advise them on the environmental benefits of on farm biogas plants with little or no energy production.
The need for AD training has been discussed with the UK Biogas trade bodies (ADBA and REA) and the Environment Agency (waste regulator in England). The need identified relates to on-farm plants where none of the feedstock is imported from outside the unit. These plants are largely unregulated by the Environment Agency (or its Welsh equivalent NRW) which then has very limited ability to intervene to ensure good practice. Whilst most reputable plant suppliers provide excellent support in the early years, the owner will often choose to run the operation themselves once the initial maintenance contract period has come to an end. SWEA organised a free training session at the “Energy Now” landowners exhibition in February 2017. The training was filmed with the intention of producing a video that can be shown at future events, distributed on DVD and uploaded onto YouTube, which will be supplemented by further material filmed at AD installations. The video film is in the final stages of completion.
Assistance to specific high quality biogas project development SWEA have worked with many sites within Wales to investigate the feasibility of on-site AD plants:
For further information you can contact the Severn Wye Energy Agency, SWEA.