Anaerobic Digestion Study for Carmarthenshire

Contents

1.         Introduction

1.1               Benefits of Anaerobic Digestion

1.2               Benefits of Renewables

 

2.         Project Mission Statement

 

3.         Aims and Objectives

 

4.         Technology Review

            4.1        History

            4.2        Development

            4.3        Overview of AD

            4.4        Process

            4.5        Nutrient management

            4.6        Types of AD Plant

                        4.6.1     On Farm systems

                        4.6.2     CAD Plants

                        4.6.3     History of Digesters in the UK

                        4.6.4     Examples

                        4.6.5     Appraisal of performance

 

5.         Resource assessment

5.1               Geographic area

5.2               Type of feedstock

5.3               Feedstock availability

5.4               Checklists for farmers

 

6.         Biogas Production

6.1        Biogas Uses

            6.2        Heat

            6.3        Electricity CHP

            6.4        Vehicle fuel

            6.5        Direct gas

           

7.         Environmental impacts

8.         Legislation

9.         Economics

            9.1        Market Barriers

            9.2        Development Funding

            9.3        Community and Co-operative Investment

            9.4        Marketing Opportunities

10.        Conclusions and Recommendations

            10.1      Business Plan for CAD Plant

            10.2      Strategy for Development of On-Farm Digester

            Appendix

            Glossary

            References

Introduction

 It is now accepted, and is part of the Constitution of the National Assembly for Wales (Section 121), that farming and life in general must become more sustainable, with regard to caretaking the environment and maintaining rural life.

Our ancestors valued and utilised the fertilizer in animal manures and organic wastes.

Intensive farming and most modern farming methods rely upon use of fossil fuels to make fertilizers and the valuable nutrients in animal manures and organic wastes is lost and soils become depleted.

Carmarthenshire is well known for its picturesque dairy farms, and the region draws tremendous economic, open space, and other benefits from its working farms. It is also well known that farming in Wales is under increasing economic, regulatory, energy, land use, and other pressures. Each year the number of active farms in Wales decreases, and once gone chances are an inactive farm will not return to active farming.

Manure management is one of the larger issues facing dairy and other farms in UK today. The traditional techniques used to manage manure on farms are coming under increasing scrutiny. There is growing interest in anaerobic digestion as a technology that can reduce pollutants, odours, and methane emissions resulting from traditional manure management techniques. Other benefits of farm-based anaerobic digestion include diversifying Carmarthenshire’s energy mix, creating new sources of renewable energy, and decreasing emissions of greenhouse gases.

Controlled anaerobic digestion is by no means a radical or new concept. Large scale industrial digesters and small domestic digesters are in operation in many places around the world. The purpose of all these digesters is to produce combustible biogas which can be burned to provide energy for a whole range of uses.

 

10.       Conclusions and Recommendations

If the AD industry is to expand significantly, several areas need to be addressed:

• The technology suffers from a perception of unreliable performance, a legacy of plant installed in the 1980s; demonstrated reliability is key as long-term performance makes plant economically feasible.
• Innovations need to concentrate on reducing capital costs and increasing the value of the process products (energy and digested material); the current uncertainty of markets for digestate represents a commercial risk which impacts on the technology's costs.
• If AD is to become economically viable without any support, there is a need to take account of the environmental benefits in the costs.
• Information on AD is still relatively scarce; there is an overall need for definitive economic and environmental information together with details of successful schemes.

Key technical areas for development, focused on improving the technology's economics, include:

• Biogas yield optimisation.
• Value engineering and modular design.
• Biogas cleaning for compatibility with natural gas systems.

Key non-technical areas include:

• Establishing reliable demonstration plant to overcome the technology's poor reputation.
• Development and dissemination of best practice.
• Encouraging self-regulation and standards within the industry, especially though trade associations.
• Development of integrated approaches to realise all the technology benefits.
• Marketing EU capability.
• Improving knowledge of AD amongst the financial community, planning community and international development banks.
• Establishing reliable cost and environmental impact data.

The development of a centralised AD plant should be planned as a business cluster, where mutually dependent businesses are located on the same site to reduce transportation costs and particularly to maximise the use of heat and electricity generated from the plant. Design should be based upon the concept of a bio-refinery where the products and co-products of processing a biological resource become the feedstocks for further industries. Businesses could include compost sales, fish farming, horticulture and other small enterprises particularly those that would utilise heat and electricity produced from the AD plant. Ideally the site should be designed with the appropriate facilities for such businesses to be in place at an early stage, with the potential for development and evolution.

The Cross Hands Industrial Estate is recommended as being a suitable site for a CAD plant in Carmarthenshire (see Figures 10.1 and 10.2)

 

Gelli Aur Farm College AD Project

Whilst a centralised AD plant could employ local people in its construction and operation it is envisaged in this report that there are only a limited number of opportunities for centralised AD plant in Carmarthenshire. However the potential for small-scale on-farm digesters is much greater and with awareness raising and a series of these digesters to act as demonstration models to farmers it is possible demand could be considerable. If there is funding available for the production of a number of small scale digesters there could opportunity for local manufacture. The design of the digesters could initially come from existing manufacturers (with a royalty payment) before, with the experience of construction, developing an original design. With initial funding for a series of small on-farm digesters that would be given free or at substantially reduced capital cost to farmers the benefits of production line manufacture could dramatically reduce costs for subsequent production.

As the use of AD develops there is considerable scope for research and development of a generic digester with built in opportunity for digester size increase as and when the farmer can secure further feedstock, thus a small scale digester could be modified on-farm in the light of experience and new opportunities. Thus ideally the design of the on-farm digester should be modular to incorporate the facility to easily increase digester size on site. There will also be opportunities for research into the use of locally reprocessed materials for digester manufacture and insulation.

The Farm College at Gelli Aur has been identified as a suitable demonstration site for a small scale farm digester.