biogas

The main reason for using anaerobic digestion, which generates biogas as a by-product, is to treat wastes.

The COD (chemical oxygen demand, a measure of pollutant concentration) of wastewater from a distiller often reaches 40 000 mg/litre while aerobic treatment only permits COD below 1 000 mg/litre, which means having to dilute the wastewater 40 times. With anaerobic digestion, 90% of the pollutants can be readily removed, thereby greatly reducing pollution to farmland, rivers and lakes.

The second main reason for anaerobic digestion is that methane is a major greenhouse gas, second to carbon dioxide in amount generated, but with a global warming potential 22 times that of carbon dioxide. Using biogas not only removes polluting wastes, but also mitigates global warming. The methane flux from exposed slurry is 3.92 mg per square metre per hour, compared with 10.26 mg per square metre per hour from compost in rice fields. Methane mitigation saves carbon emissions and is a tradeable commodity.

An anaerobic digester can solve sanitation problems by taking in human as well as animal manure, improving home and farm hygiene and the general environmental conditions.

Anaerobic digestion not only yields biogas but also bio-slurry and bio-dregs rich in nutrients, minerals and biologically active compounds that form excellent organic fertiliser for crops and fodder for pig and fish.

1. Cooking, co-generation of electricity and heat - Biogas can be used directly for cooking and for co-generation of electricity and heat, which is especially feasible when the biogas is used at or near the site of generation.
2. Transport Fuel - Biogas methane can also be used as fuel for vehicles, and is the cleanest biofuel available. Cars run on biogas methane have been voted environmental cars of the year in 2005. Thousands of them are already operating in Sweden, which has hundreds of filling stations supplied by community biogas digesters [12] (Organic Waste-Powered Cars). See also further information here -
3. Heat and light - Biogas can be used in ovens and lamps to heat greenhouses and at the same time increase the carbon dioxide concentration to boost photosynthesis in the greenhouse plants and increase yields.
4. Methanol production - Biogas methane can also be used to make methanol, an organic solvent and important chemical for producing formaldehyde, chloromethane, organic glass, and compound fibre.
5. Preservation - Biogas can be used to prolong storage of fruit and grain. An atmosphere of methane and carbon dioxide inhibits metabolism, thereby reducing the formation of ethylene in fruits and grains. It also kills harmful insects, mould, and bacteria that cause diseases

Advantages of biogas

• Use as a renewable fuel
• Waste is disposed of at the same time and in the same operation
• Consumes methane that might otherwise leak into the atmosphere and increase the greenhouse effect
• Biogas can also be used on a small scale, eg a pig farm

Disadvantages of biogas

• The main disadvantage is the loss of the organic waste for compost or fertiliser
• Very limited in the quantity of electricity it can produce on the global scale
• There is little or no control on the rate of gas production, although the gas can, to some extent be stored and used as required.

1. Anaerobic digestion - Anaerobic digestion is the process in which volatile organic material sare broken down in the absence of oxygen. This biological process produces a gas, sometimes called biogas, principally composed of methane and carbon dioxide.
2. more details to come...

An Assessment of Environmental Effects (AEE) must accompany each application for a resource consent under the Resource Management Act.

The Ministry for the Environment has prepared a “ Guide to preparing a Basic Assessment of Environmental Effects ” accessible here . This guide is intended to help applicants understand the process and prepare a simple assessment of environmental effects.

NEW - New Zealand Pork (NZ Pork) is working in collaboration with the Ministry of Agriculture (MAF) and the Energy Efficiency and Conservation Authority (EECA) to support the assessment and uptake of biogas technology within the NZ pork industry. NZ Pork has prepared a document, the aim of which. is to provide information to assist assessment of environmental effects associated with farm biogas systems, particularly in relation to requirements of the Resource Management Act 1991 (RMA). This document is primarily intended for project developers and local authority policy and consent staff. For further details, contact Elizabeth McGruddy, Environment Officer for New Zealand Pork.

The key focus of legislation and regulations pertaining to biogas largely cover odour and environmental effects (including waste management and pollution prevention) and the generation of renewable energy. Carbon dioxide and equivalent mitigation are more recent issues covered by legislation. Safety is an additional issue.

Key pieces of legislation include:

• The Resource Management Act 1991 - coming soon...
• The New Zealand Energy Strategy 2007 - coming soon...
• National Policy Statement (NPS) for Renewable Electricity Generation 2008 (proposed) - coming soon...
• Draft Climate Change (Stationary Energy and Industrial Processes) Regulations 2009 - coming soon....

The key Government Ministries involved in the regulation of (or with an interest in) biogas generation in New Zealand are:

• The Ministry for the Environment (MfE)
• The Ministry of Economic Development (MED)
• The Energy Efficiency and Conservation Authority (EECA) and,
• The Ministry of Agriculture and Forestry (MAF).

Ministry for the Environment (MfE)

coming soon....

Ministry of Economic Development (MED)

MED's main interest in biogas is in the generation potential and in the CO2 emissions from biomass combustion as part of the inventory of Green House Gas (GHG) emissions.

Details of the CO2 emissions from biomass (including wood and biogas [landfill and sewage gas]) are available here in the NZ Energy Greenhouse Gas Emissions 1990 – 2007 Report.

Energy Efficiency and Conservation Authority (EECA)

The Energy Efficiency and Conservation Authority (EECA) promotes sustainable energy by changing the way New Zealanders think about, and use energy. EECA works to raise community awareness of energy efficiency and renewable energy issues and provides businesses and individuals with the tools to make changes. EECA develops programmes to meet the needs of specific markets, often working in partnership with other organisations. As part of its Renewable Energy Programme EECA promotes activities on bioenergy generally and including biofuels in order to encourage uptake. EECA produces a considerable range of information and resources relating to biofuels, their production and use. Further details about EECA's activities in relation to biogas are available here .

Specific EECA Resources include:

• Biogas and Landfill gas Factsheet
• Distributed Generation Pilot Feasibility Fund - more details here.

In 2008 EECA and NZPork launched a project to evaluate the use of manure in different biogas systems on farms. The project was designed to investigate the feasibility of on-farm biogas generation at different scales and in different locations and the results will inform farmers and their partners of the most effective opportunities for farms. The following reports present the details of studies undertaken as part of this project (2008-2010).

• Feasibility Study for Construction and Operation of a Regional Digester Facility (author – CPG/ Waste Solutions)
• Aorere Farms Piggery Covered Anaerobic Pond Design (author – NIWA)
• Reid’s Piggery Covered Anaerobic Pond Design (author – NIWA)
• Windy Farm Piggery Covered Anaerobic Pond Design  (author NIWA)
• Feasibility study report: Digestion of piggery waste At PIC’s Te Pirita facility (author - East Harbour Energy Limited)
  

Ministry of Agriculture and Forestry (MAF)

MAF manages the Sustainable Farming Fund (SFF).

Specific MAF Resources include:

1. Methane from Animal Waste Management Systems, Oct 2008 (Consultancy Report) - This report describes research conducted as part of MAF's Climate Change “Plan of Action” Research Programme 2007/8 on the sub-category topic of “Methane from Animal Waste Management Systems”. Greenhouse gas (GHG) emissions from animal wastes are described and the sources of the specific greenhouse gases carbon dioxide, methane and nitrous oxide in the context of animal wastes management are outlined. It is important in this research to set down in some detail the current animal waste management methodologies on New Zealand farms for dairy, pig and poultry wastes because these methods, and possible future enhancements to them, have much relevance to on-farm methane generation and an accompanying controlled approach to collecting and utilising these emissions via anaerobic lagoons or biogas digesters. Accordingly, Section 3 of this report describes these current collection and management methods for dairy, pig and poultry wastes. Further details here .
   

2. Dairy Shed Wastewater – Ponds and other treatment options prior to discharge or land application , (Oct 1994)
   

3. SFF Project – ‘Waste to Wealth' – New Zealand Pork (March 2009)- This project explores the potential of pork producers linking with other Canterbury stakeholders to collectively supply a biogas plant that combines both pig and other commercial waste with the aim of generating energy, fertiliser and dealing with issues of waste management and odour. Pork Producers in Canterbury have shown a strong interest in exploring this concept further and have asked for assistance to initiate the first steps. The output will be a report establishing the initial feasibility and the willingness of collective Canterbury stakeholders to undertake a full feasibility. Whether or not the concept is feasible in Canterbury, a process and roadmap will be developed that can be applied elsewhere in New Zealand.

More details (SFF Project Summary and Rational) available here .

MAF also funds research in its Sustainable Land Use Adaptation to Climate Change (SLMACC) programme. A new biogas project is" 'Closed Loop N-Supply Biofuel Crops' (July 2009). This project aims to provide a major boost to rural biogas production while making sustainable use of marginal land to grow the biomass feedstock. By choosing biogas as the biomass conversion technology the nutrients such as nitrogen will be largely captured and can be returned to the crop land. An appropriate proportion of the biomass crops will be legumes, enhancing N in the crop to fuel cycle and creating a surplus of N from the biomass cropping that can be supplied to food crops. The project will also use models to assess the feedstock production potential of NZ marginal lands.

coming soon...

Projet Profiles

1. Entec - Christchurch Trigeneration Project Summary, 2010,

Fact Sheets

1. Biogas Digestate Factsheet, Renquist and Heubeck, November 2009

New Zealand focused articles

1. For Food Scraps, Get Waste
2. Biogas from Green and Putrescible Waste in New Zealand, Jo Knight, CEO, Zero Waste New Zealand Trust
3. Go with the flow- South Auckland-based Flotech is making a pile converting unmentionables into vehicle fuel.
4. Presentation - Jurgen Thiele, Waste Solutions Ltd: Overview of New Zealand's Biogas Potential (2008)
5. Report - Waste Solutions Ltd: Bioenergy Options Project PROJ-12011-ORI-FRIO - Bioenergy Resource Assessment Municipal Biosolids and Effluent and Dairy Factory, Meat Processing and Wool Processing Waste (2007)
6. Report - Dave Stewart, MWH: Contract CC MAF POL_2008-39 (163-4) - Methane from Animal Waste Management Systems, Final report (October 2008 )
7. Presentation - Jurgen Thiele, Waste Solutions Ltd: New Digester Systems for Pig Manure in New Zealand (November 2007 )
8. Presentation – Entec, Biogas Electricity Generation
9. Discussion document on Feed-in tariffs for aiding the uptake of small scale renewable electricity generation schemes - draft document, Stephan Heubeck (September 2009)
10. Municipal sludge digester upgrade, for biofuel production, Jürgen H Thiele, Waste Solutions, (2009)
11. Biogas Feedstock Production using Novel Crop Rotations with a Closed-Loop Nitrogen Supply, Rocky Renquist and Stephan Heubeck (February 2010)
12. Going Greener with Palmerston North City Council's Biogas to Energy Project. Jurgen Thiele, CPG, New Zealand Local Government publication, June 2010
13. Biogas Developments in Europe - Snapshots, Rocky Renquist and Stephan Heubeck (August 2010)
14. Regional Co-digestion Facilities for Piggery Manure and Selected Industrial Waste, Jurgen Thiele, CPG (June 2010)
15. Biogas plants make good use of waste in Germany, Stephan Heubeck, (NIWA and BANZ Biogas Interest Group), March 2011

See also Biogas Events

1. Biogas from waste and renewable resources: an introduction, Dieter Deublein, Angelika Steinhauser

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