Biogas
NSL on Rural Delivery - TVNZ Interview
Ian and Malcolm were interviewed by Rural Delivery, a TVNZ Saturday morning presentation.
Rural Delivery TV Interview
Rural Delivery TV Interview
Effluent to Energy (Radio NZ Country Life Interview with Ian)
Canterbury based electrical power engineer, Ian Bywater has developed an effluent-to-energy system for dairy units. (duration: 14′31″)
Podcast Read More...
Podcast Read More...
Canterbury Resource Management Awards 2008
...BioGenCool energy from dairy waste system is the winner of the EECA Special Award for Energy Efficiency, Conservation and Renewable Energy.
The project aims are the generation of energy using cow manure, greater energy self-sufficiency on-farm and conversion of cow manure to fertiliser. Judges said BioGenCool is a highly creative technology using a systems approach to take diary waste and convert it to useful on-farm resources. The project is bringing together different technologies to create an integrated system within a dairy farm... Read More...
The project aims are the generation of energy using cow manure, greater energy self-sufficiency on-farm and conversion of cow manure to fertiliser. Judges said BioGenCool is a highly creative technology using a systems approach to take diary waste and convert it to useful on-farm resources. The project is bringing together different technologies to create an integrated system within a dairy farm... Read More...
Offshore Firms Eye NZ Dairy Power from Gas
28/10/08 19:02 Filed in: Biogas | Electricity
by Malcolm Mountfort , 28/10/2008,
(c) 2008 Rural News Group, www.ruralnews.co.nz
A Christchurch company is sparking international interest in its BioGen system for energy recovery from dairy waste.
The system captures methane and carbon dioxide from dairyshed and feedpad effluent to fire hot water boilers and, if economic, to generate electricity. Read More...
(c) 2008 Rural News Group, www.ruralnews.co.nz
A Christchurch company is sparking international interest in its BioGen system for energy recovery from dairy waste.
The system captures methane and carbon dioxide from dairyshed and feedpad effluent to fire hot water boilers and, if economic, to generate electricity. Read More...
Finding Power in Effluent
By TIM CRONSHAW - The Press | Friday, 29 August 2008
A dairying system that is turning effluent into power and fertiliser in Canterbury is expected to revolutionise the way farmers treat cow muck.
Its investors have set up a pilot plant at a Landcorp Farming dairy farm in Eyrewell that is extracting methane and carbon dioxide from effluent with biodigester technology, and using it as fuel in a co-generation plant to make electricity. Read More...
A dairying system that is turning effluent into power and fertiliser in Canterbury is expected to revolutionise the way farmers treat cow muck.
Its investors have set up a pilot plant at a Landcorp Farming dairy farm in Eyrewell that is extracting methane and carbon dioxide from effluent with biodigester technology, and using it as fuel in a co-generation plant to make electricity. Read More...
Lighting up with cow-power
18/08/08 21:45 Filed in: Biogas | BioGenCool
By Angela Gregory (www.NZHerald.co.nz)
Power generated from cow dung has been identified as one way New Zealand could make billions from an emissions trading scheme.
The work of a Christchurch company in using biomass for electricity generation is offered as an example of a business opportunity in a report issued this morning as a curtain-raiser to a climate change conference in Auckland.
The 4th Australia-New Zealand Climate Change and Business Conference will be attended tomorrow morning by the Prime Ministers of Australia and New Zealand, Kevin Rudd and Helen Clark, who will give their views on climate change.
British Prime Minister Gordon Brown has also agreed to participate in the conference by making a video address.
More than 80 expert speakers from around the world will explore current climate change issues of relevance to business, such as implementing emissions trading and investments.
At the NZ Business Council for Sustainable Development's "clean billions" breakfast at SkyCity today, a report for the Tindall Foundation will be issued in support of Stephen Tindall chairing the climate change leadership forum, which advises ministers on emissions trading.
The report says businesses will be expected to go beyond "carbon neutral" to become "carbon negative" .
It says many New Zealand firms are behind those in other countries in measuring the potential effects of pricing carbon and preparing plans to reduce it.
But it softens the blow by adding that opportunities are available for businesses and the economy which actively embrace emissions trading and make efforts to cut emissions, improve products and reduce emissions costs.
The report says businesses could make billions from new technology investments stimulated by the proposed emissions trading scheme.
Some of the main opportunities are included in biomass-like opportunities for some farmers to generate electricity from cow manure methane.
Natural Systems is already running a pilot project on a Landcorp dairy farm in North Canterbury.
Technical director Ian Bywater said a farmer with 850 cows (with feedpad) could save up to $30,000 a year in electricity costs.
The work of a Christchurch company in using biomass for electricity generation is offered as an example of a business opportunity in a report issued this morning as a curtain-raiser to a climate change conference in Auckland.
The 4th Australia-New Zealand Climate Change and Business Conference will be attended tomorrow morning by the Prime Ministers of Australia and New Zealand, Kevin Rudd and Helen Clark, who will give their views on climate change.
British Prime Minister Gordon Brown has also agreed to participate in the conference by making a video address.
More than 80 expert speakers from around the world will explore current climate change issues of relevance to business, such as implementing emissions trading and investments.
At the NZ Business Council for Sustainable Development's "clean billions" breakfast at SkyCity today, a report for the Tindall Foundation will be issued in support of Stephen Tindall chairing the climate change leadership forum, which advises ministers on emissions trading.
The report says businesses will be expected to go beyond "carbon neutral" to become "carbon negative" .
It says many New Zealand firms are behind those in other countries in measuring the potential effects of pricing carbon and preparing plans to reduce it.
But it softens the blow by adding that opportunities are available for businesses and the economy which actively embrace emissions trading and make efforts to cut emissions, improve products and reduce emissions costs.
The report says businesses could make billions from new technology investments stimulated by the proposed emissions trading scheme.
Some of the main opportunities are included in biomass-like opportunities for some farmers to generate electricity from cow manure methane.
Natural Systems is already running a pilot project on a Landcorp dairy farm in North Canterbury.
Technical director Ian Bywater said a farmer with 850 cows (with feedpad) could save up to $30,000 a year in electricity costs.
NZ Farmers Generate Energy from Biogas
According to Radio New Zealand, with the increase in fuel and power prices, farmers are thinking up new ways of tapping into their own energy sources.
South Island cropping farmers are now growing thousands of hectares of oilseed rape under contract to the biofuel company, Biodiesel New Zealand.
But some are also growing the brassica to provide oil for their own diesel powered farm vehicles and machinery.
They include Earl and Vicki Dillon, who grow wheat, barley and other crops on their farm near Balfour in Southland.
They have just won the region's top farm environment award for their farming practices, which include using minimum tillage methods such as direct drilling to protect the soil structure and reduce compaction.
Earl Dillon says they are also growing rape to provide fuel for their grain drier. They have imported an extractor which produces squeezed oil. He says it will not be refined into biodiesel.
An energy technology company, Natural Systems Limited, has set up a pilot plant on a Landcorp farm.
The biogas, a combination of methane and carbon dioxide, is produced in a digester that processes dung and urine collected from the dairy shed holding yard.
It powers an engine that generates electricity, as well as providing heating and cooling.
The company's technical director, Ian Bywater, says he believes it is the only system operating on a New Zealand farm that puts electricity back into the national grid.
He says about a third of the energy usually bought through the meter will be supplied from this source.
He also says the size of the dairy industry makes it possible for more manure to be collected and therefore more energy to be produced locally, where it is needed.
TheBioenergySite News Desk
South Island cropping farmers are now growing thousands of hectares of oilseed rape under contract to the biofuel company, Biodiesel New Zealand.
But some are also growing the brassica to provide oil for their own diesel powered farm vehicles and machinery.
They include Earl and Vicki Dillon, who grow wheat, barley and other crops on their farm near Balfour in Southland.
They have just won the region's top farm environment award for their farming practices, which include using minimum tillage methods such as direct drilling to protect the soil structure and reduce compaction.
Earl Dillon says they are also growing rape to provide fuel for their grain drier. They have imported an extractor which produces squeezed oil. He says it will not be refined into biodiesel.
"We'll be able to burn it through the diesel burner, which fires the wheat dryer."
Biogas generated electricity
Meanwhile, a dairy farm in Canterbury is generating electricity from biogas extracted from cow dung.An energy technology company, Natural Systems Limited, has set up a pilot plant on a Landcorp farm.
The biogas, a combination of methane and carbon dioxide, is produced in a digester that processes dung and urine collected from the dairy shed holding yard.
It powers an engine that generates electricity, as well as providing heating and cooling.
The company's technical director, Ian Bywater, says he believes it is the only system operating on a New Zealand farm that puts electricity back into the national grid.
He says about a third of the energy usually bought through the meter will be supplied from this source.
He also says the size of the dairy industry makes it possible for more manure to be collected and therefore more energy to be produced locally, where it is needed.
View the Radio New Zealand story by clicking here."That relieves the transmission and distribution network."
TheBioenergySite News Desk
NSL Most Exciting Green Technology Company in NZ - NBR
Graeme Kennedy [NBR] see: www.excitingcompanies.co.nz
Christchurch company Natural Systems has developed an on-farm process to extract methane gas from dairy cow manure to generate electricity in a breakthrough that could save farmers thousands of dollars and clean the environment.
The system, BioGenCool, is operating on one of Landcorp’s 30 dairy farms with good results and is attracting strong interest from New Zealand farmers and others in Australia and the UK.
Natural Systems technical director Ian Bywater said the large amounts of waste had now become a commercially viable energy source. New Zealand’s four million dairy cows dumped a daily 200,000 tonne manure mountain with around 10% dropped on concrete hard stands such as dairy yards and supplemental feeding areas.
This waste could yield 80 mega-watts of power, Mr Bywater said. A farmer with 850 cows and a feed pad could save up to $30,000 a year in electricity costs through the BCG system.
“New Zealand has 12,000 dairy farms but that number is decreasing as they become bigger,” Mr Bywater said. “That means the market is coming to us with larger herds and more product to convert into fuel. And there are wider environmental benefits including less nitrate runoff and greenhouse gas abatement.”
Natural Systems topped the environmental technologies sector in The National Business Review’s monthly Exciting Companies series with a rating of 69.5 based on surveys by strategic business consultancy New River.
It led International Global Change Institute, Powersmart NZ, EnviroWaste NZ and Aquaflow Bionomic Corporation.
An electrical power engineer, Mr Bywater’s manure-to-electricity concept won a worldwide Engineering for a Sustainable Future competition organised by the UK Institute for Engineering and Technology in 2003.
“I had always had a strong interest in sustainability and renewable energy,” he said.
“I decided this should have commercial value and formed Natural Systems with two partners. Dairy is New Zealand’s biggest export earner and the concept was a process extracting valuable energy from a waste product to smooth out electrical demand and make savings on dairy farms.
“It can freeze water to chill milk, drive milking machinery and reduce imported power.”
The company carried out computer modelling of the system’s theoretical effects and conducted an energy report on a North Canterbury farm. State-owned Landcorp senior management supported the programme’s economic benefits and environmental value.
Mr Bywater said manure scraped from milking yards and increasing numbers of feed pads would be placed in 180,000-litre digesters heated to 35 degrees to liberate bio-gases made up of 65% methane and the rest carbon dioxide.
The gas is mixed with 15% diesel as its ignition source to run an engine and drive a generator.
Mr Bywater said the system cost depended on farm size but installation could be up to $200,000 for the largest properties.
BRING IT ON
Demand for environmental technology is booming, with 80% of respondents rating the sector as either very buoyant or buoyant, the New River survey found.
“There is a lot of growth in demand for solutions in industries with obvious issues such as dairy, and the number of consumers interested in these issues has increased dramatically in the past few years,” it said.
“It is becoming mainstream with more pressure on polluters to clean up as consumers demand more environmentally friendly products. Local government is pressuring clients, tourists want to see sustainable management and specific industry segments such as waste management materials recovery are caught up in the China-driven resource boom.
“There are now dozens of environmental technology companies, most of which are still small, working in traditional areas from cleaning up waste water and solid waste management. Newer areas include energy saving, climate change location forecasting and conversion of waste to energy and fertilizer.”
New River said, however, that a lack of clear government guidelines on emissions trading was slowing work in the energy sector.
“Businesses are unsure which clean technologies are going to be the most cost-competitive,” it said. “There is also no wider government policy framework for environmental issues — and this is creating uncertainty.”
Christchurch company Natural Systems has developed an on-farm process to extract methane gas from dairy cow manure to generate electricity in a breakthrough that could save farmers thousands of dollars and clean the environment.
The system, BioGenCool, is operating on one of Landcorp’s 30 dairy farms with good results and is attracting strong interest from New Zealand farmers and others in Australia and the UK.
Natural Systems technical director Ian Bywater said the large amounts of waste had now become a commercially viable energy source. New Zealand’s four million dairy cows dumped a daily 200,000 tonne manure mountain with around 10% dropped on concrete hard stands such as dairy yards and supplemental feeding areas.
This waste could yield 80 mega-watts of power, Mr Bywater said. A farmer with 850 cows and a feed pad could save up to $30,000 a year in electricity costs through the BCG system.
“New Zealand has 12,000 dairy farms but that number is decreasing as they become bigger,” Mr Bywater said. “That means the market is coming to us with larger herds and more product to convert into fuel. And there are wider environmental benefits including less nitrate runoff and greenhouse gas abatement.”
Natural Systems topped the environmental technologies sector in The National Business Review’s monthly Exciting Companies series with a rating of 69.5 based on surveys by strategic business consultancy New River.
It led International Global Change Institute, Powersmart NZ, EnviroWaste NZ and Aquaflow Bionomic Corporation.
An electrical power engineer, Mr Bywater’s manure-to-electricity concept won a worldwide Engineering for a Sustainable Future competition organised by the UK Institute for Engineering and Technology in 2003.
“I had always had a strong interest in sustainability and renewable energy,” he said.
“I decided this should have commercial value and formed Natural Systems with two partners. Dairy is New Zealand’s biggest export earner and the concept was a process extracting valuable energy from a waste product to smooth out electrical demand and make savings on dairy farms.
“It can freeze water to chill milk, drive milking machinery and reduce imported power.”
The company carried out computer modelling of the system’s theoretical effects and conducted an energy report on a North Canterbury farm. State-owned Landcorp senior management supported the programme’s economic benefits and environmental value.
Mr Bywater said manure scraped from milking yards and increasing numbers of feed pads would be placed in 180,000-litre digesters heated to 35 degrees to liberate bio-gases made up of 65% methane and the rest carbon dioxide.
The gas is mixed with 15% diesel as its ignition source to run an engine and drive a generator.
Mr Bywater said the system cost depended on farm size but installation could be up to $200,000 for the largest properties.
BRING IT ON
Demand for environmental technology is booming, with 80% of respondents rating the sector as either very buoyant or buoyant, the New River survey found.
“There is a lot of growth in demand for solutions in industries with obvious issues such as dairy, and the number of consumers interested in these issues has increased dramatically in the past few years,” it said.
“It is becoming mainstream with more pressure on polluters to clean up as consumers demand more environmentally friendly products. Local government is pressuring clients, tourists want to see sustainable management and specific industry segments such as waste management materials recovery are caught up in the China-driven resource boom.
“There are now dozens of environmental technology companies, most of which are still small, working in traditional areas from cleaning up waste water and solid waste management. Newer areas include energy saving, climate change location forecasting and conversion of waste to energy and fertilizer.”
New River said, however, that a lack of clear government guidelines on emissions trading was slowing work in the energy sector.
“Businesses are unsure which clean technologies are going to be the most cost-competitive,” it said. “There is also no wider government policy framework for environmental issues — and this is creating uncertainty.”
Energy : Effluent power goes high-tech
Energy : Effluent power goes high-tech
By Anne LeeA Christchurch company has begun a farm-scale trial of a system that can use effluent to make electricity, heat water and cool milk.
BioGenCool, produced by Natural Systems, is projected to cut around one third off the electricity bill for farm dairies. At the same time it will provide rapid and constant milk cooling, improve the quality of the effluent, reduce greenhouse gas emissions and reduce water use.
Landcorp Farming is about to trial the system on its 850-cow Waimakariri dairy farm near Christchurch. Read More...
Biomass to Cogeneration for NZ Dairy Farms
01/10/05 14:26 Filed in: Biogas | Energy Efficiency
Biomass to cogeneration for New Zealand dairy farms Dairy farms could form an ideal application for cogeneration plants fuelled by biogas produced on-site by the anaerobic digestion of manure. Such a solution would cut farmers’ electricity bills and help to solve a waste disposal problem, writes Ian Bywater... Read More...
EXPERT SHOWS FARMERS HOW TO TURN COW PATS INTO KILOWATTS
27/10/04 15:45 Filed in: Biogas | Electricity
Island farmers are to have the opportunity to find out from an international expert about a system for turning cow manure into a clean, environmentally friendly energy source.
Ian Bywater, a New Zealand based engineer, will be visiting the Isle of Wight on Wednesday 10 November as part of a whistle stop tour of the UK. Mr Bywater has invented an anaerobic digestion (AD) system for dairy farmers. This fully integrated energy system project won him the New Spirit Challenge competition and the Institute of Electrical Engineers’ Award for Sustainability in 2003.
The Isle of Wight’s Renewable Energy Strategy recognises the potential for small-scale AD systems based on cow manure. The council’s Agenda 21 Co-ordinator, Jim Fawcett, came across the application, geared to the size of dairy farms on the Island and invited Mr Bywater to meet farmers individually if they are interested in looking at the system in more detail. He should be able to give them some idea of fuel cost savings on their current operation.
Ian’s system combines three technologies to reduce energy bills and environmental pollution. Cowshed waste is placed in a bio-digester to produce biogas. The spent sludge from the digester is a higher grade of fertiliser for grassland than raw manure while the biogas is used as fuel for a sterling type engine generator set, which produces both electricity and heated water. This powers an ice bank, which cools milk. He said: “The technologies are individually well developed but not exploited; It is the combination of all three that makes the system viable, especially today where there are concerns about environmental pollution and use of non-renewable energy.”
Ian Bywater is seeking research funding to enable a demonstration system to be installed both in New Zealand and the UK. He is also currently looking for test sites for the system in the UK. Any dairy farmers interested should contact Jim Fawcett on (01983) 823204 or Jim.Fawcett@iow.gov.uk
END
Ian Bywater, a New Zealand based engineer, will be visiting the Isle of Wight on Wednesday 10 November as part of a whistle stop tour of the UK. Mr Bywater has invented an anaerobic digestion (AD) system for dairy farmers. This fully integrated energy system project won him the New Spirit Challenge competition and the Institute of Electrical Engineers’ Award for Sustainability in 2003.
The Isle of Wight’s Renewable Energy Strategy recognises the potential for small-scale AD systems based on cow manure. The council’s Agenda 21 Co-ordinator, Jim Fawcett, came across the application, geared to the size of dairy farms on the Island and invited Mr Bywater to meet farmers individually if they are interested in looking at the system in more detail. He should be able to give them some idea of fuel cost savings on their current operation.
Ian’s system combines three technologies to reduce energy bills and environmental pollution. Cowshed waste is placed in a bio-digester to produce biogas. The spent sludge from the digester is a higher grade of fertiliser for grassland than raw manure while the biogas is used as fuel for a sterling type engine generator set, which produces both electricity and heated water. This powers an ice bank, which cools milk. He said: “The technologies are individually well developed but not exploited; It is the combination of all three that makes the system viable, especially today where there are concerns about environmental pollution and use of non-renewable energy.”
Ian Bywater is seeking research funding to enable a demonstration system to be installed both in New Zealand and the UK. He is also currently looking for test sites for the system in the UK. Any dairy farmers interested should contact Jim Fawcett on (01983) 823204 or Jim.Fawcett@iow.gov.uk
END
Sorting the Brass from the Muck
Ian Bywater’s work on energy savings in dairy farming.
In 2003, SEF member Ian Bywater won the New Spirit Challenge award, offered by the UK Institution of Electrical Engineers for an engineering project that promotes sustainability. Entries must show multidisciplinary thinking and imagination as well as novelty, and offer potential opportunities for the engineering community.
The latest news is that research on the main components of the system is complete and application has been made for grants to fund a demonstration plant for a dairy herd of 200 cows.
The problem Many network companies are experiencing a growing electrical load on rural networks, due to the rapid increase in dairying in New Zealand. In addition to the general problem of increasing demand, there are undesirable morning and evening system peaks caused by the refrigeration load. The total load can strain long rural power systems that are often not designed for such loadings.
capacity if the network supply fails.
•A biodigester to treat the dairy shed effluent, providing a primary source of energy. Initial trials
will have electrical backup, but LPG is another option if only occasional backup is needed.
•A Stirling engine to generate power from biogas.
•Solar thermal heating for shed hot water.
•Local groundwater for initial milk cooling, if available.
•Further integration, such as using biogas or waste heat from the Stirling engine to heat water for shed use, and hot water to maintain the biodigester at optimum temperature.
The potential benefits of such as system include reduced electrical energy use; further reductions in peak electrical energy use; improved effluent disposal; reduced methane emissions; and reduced investment in rural power supplies.
The award judges envisaged several stages in project development, provided that each preceding stage is a success:
•Undertake a desktop study into the energy balance of the system.
•Undertake a world-wide search of suitable suppliers of equipment.
•Formulate a system as described and seek research funding.
•Operate an ice bank for a number of daily cycles to determine its characteristics in a laboratory and report back the test results.
•Operate the digester for a number of weeks to determine its characteristics in a laboratory.
•Use the biogas produced to fuel a Stirling engine, and report back the test results.
•Combine the ice bank operation with the power output from the Stirling engine generator.
•In conjunction with a network company, locate a suitable dairy farm where the system will be
installed. This ‘on-farm’ situation will enable a comparison between operations with and without
the ice bank.
•Analyse and report on the results.
•Commercial development.
A herd of 200 cows producing 2000 l of milk at each milking requires a cooling capacity of 70 kWh, or 35 kW for two hours. For a typical refrigeration unit with a CoP of about 2–3 this requires about 12–18 kW of electrical compressor power.
The load can be reduced by using local ground water as a heat sink for the first stage of cooling, from say 37–25˚C. This will reduce the power requirement by about 40%, but at the expense of drawing about 2 l of water from the aquifer for each litre of milk cooled.
Using an ice-bank to store cooling capacity reduces the load, and also the size of refrigeration equipment, making it more environmentally beneficial. In this way the two-hour cooling requirement can be met from ice generated over a period of up to 12 hours. This will need a
refrigeration system only about 1/6 as large; 2–3 kW capacity for total cooling, or 1.5– 2.0 kW if used with water as an initial cooling agent. The amount of ice required is about 400 g/l of milk (latent heat of fusion 320 kJ/kg, specific heat of milk 4.2 kJ/lK, cooling range 30 K), or just under 800 kg for 2000 l.
For two-stage cooling the ice requirement is about 60% of this, or around 500 kg.
The operation of the ice-bank is as follows:
•During the ice making period the refrigeration system runs continuously at a capacity of 6 kW
(cooling) or about 2 kW (electrical). This load can be met by a Stirling engine running on biogas,
with LPG available as a back-up energy source.
•During the milk cooling period the ice is melted to produce water at 0˚C (or cooler if a lowered freezing-point fluid is used). This cools the milk to 7˚C, and in doing so, its temperature rises to say 2˚C. The ‘warm water’ is recycled to the ice-bank where it is re-cooled to 0˚C by melting more ice.
By the end of the milk-cooling period, all the ice has melted and all the milk has been cooled. The cycle begins again.
Hot water is also needed; very roughly 300 l /day at 85˚C. This typically uses a 6 kW electric heater, but some large farms use a 1200 l tank with a14 kW element (with permission from the retailer). In a more sustainable system, energy for water heating could come from a solar heater; waste heat from the Stirling engine; biogas; mains electricity; or LPG, in about that order of priority (but probably not all in the same installation!).
Clearly a fully integrated system is going to be fairly expensive and need some fairly sophisticated
controls, but with some very real benefits available.
This article is largely taken from the New Spirit Challenge award notice with additional information from Ian Bywater and Malcolm Souness
In 2003, SEF member Ian Bywater won the New Spirit Challenge award, offered by the UK Institution of Electrical Engineers for an engineering project that promotes sustainability. Entries must show multidisciplinary thinking and imagination as well as novelty, and offer potential opportunities for the engineering community.
The latest news is that research on the main components of the system is complete and application has been made for grants to fund a demonstration plant for a dairy herd of 200 cows.
The problem Many network companies are experiencing a growing electrical load on rural networks, due to the rapid increase in dairying in New Zealand. In addition to the general problem of increasing demand, there are undesirable morning and evening system peaks caused by the refrigeration load. The total load can strain long rural power systems that are often not designed for such loadings.
The proposal
•An ice bank to reduce the peak refrigeration load, by spreading it over 6–12 hours instead of a 2 hour milking period. Ice banks have other benefits to the dairy industry, such as reserve coolingcapacity if the network supply fails.
•A biodigester to treat the dairy shed effluent, providing a primary source of energy. Initial trials
will have electrical backup, but LPG is another option if only occasional backup is needed.
•A Stirling engine to generate power from biogas.
•Solar thermal heating for shed hot water.
•Local groundwater for initial milk cooling, if available.
•Further integration, such as using biogas or waste heat from the Stirling engine to heat water for shed use, and hot water to maintain the biodigester at optimum temperature.
The potential benefits of such as system include reduced electrical energy use; further reductions in peak electrical energy use; improved effluent disposal; reduced methane emissions; and reduced investment in rural power supplies.
The award judges envisaged several stages in project development, provided that each preceding stage is a success:
Stage 1
•Undertake a desktop study into the energy balance of the system.
•Undertake a world-wide search of suitable suppliers of equipment.
•Formulate a system as described and seek research funding.
Stage 2
•Operate an ice bank for a number of daily cycles to determine its characteristics in a laboratory and report back the test results.
•Operate the digester for a number of weeks to determine its characteristics in a laboratory.
•Use the biogas produced to fuel a Stirling engine, and report back the test results.
•Combine the ice bank operation with the power output from the Stirling engine generator.
Stage 3
•In conjunction with a network company, locate a suitable dairy farm where the system will be
installed. This ‘on-farm’ situation will enable a comparison between operations with and without
the ice bank.
•Analyse and report on the results.
Stage 4
•Commercial development.
The numbers
Dairy farms generally operate on a regular, twice-a-day milking pattern, although once-a-day is becoming more common and milk collection may be only every other day. The milk comes from the cow at about 37˚C and needs to be cooled to below 7˚C within two hours of milking.A herd of 200 cows producing 2000 l of milk at each milking requires a cooling capacity of 70 kWh, or 35 kW for two hours. For a typical refrigeration unit with a CoP of about 2–3 this requires about 12–18 kW of electrical compressor power.
The load can be reduced by using local ground water as a heat sink for the first stage of cooling, from say 37–25˚C. This will reduce the power requirement by about 40%, but at the expense of drawing about 2 l of water from the aquifer for each litre of milk cooled.
Using an ice-bank to store cooling capacity reduces the load, and also the size of refrigeration equipment, making it more environmentally beneficial. In this way the two-hour cooling requirement can be met from ice generated over a period of up to 12 hours. This will need a
refrigeration system only about 1/6 as large; 2–3 kW capacity for total cooling, or 1.5– 2.0 kW if used with water as an initial cooling agent. The amount of ice required is about 400 g/l of milk (latent heat of fusion 320 kJ/kg, specific heat of milk 4.2 kJ/lK, cooling range 30 K), or just under 800 kg for 2000 l.
For two-stage cooling the ice requirement is about 60% of this, or around 500 kg.
The operation of the ice-bank is as follows:
•During the ice making period the refrigeration system runs continuously at a capacity of 6 kW
(cooling) or about 2 kW (electrical). This load can be met by a Stirling engine running on biogas,
with LPG available as a back-up energy source.
•During the milk cooling period the ice is melted to produce water at 0˚C (or cooler if a lowered freezing-point fluid is used). This cools the milk to 7˚C, and in doing so, its temperature rises to say 2˚C. The ‘warm water’ is recycled to the ice-bank where it is re-cooled to 0˚C by melting more ice.
By the end of the milk-cooling period, all the ice has melted and all the milk has been cooled. The cycle begins again.
Hot water is also needed; very roughly 300 l /day at 85˚C. This typically uses a 6 kW electric heater, but some large farms use a 1200 l tank with a14 kW element (with permission from the retailer). In a more sustainable system, energy for water heating could come from a solar heater; waste heat from the Stirling engine; biogas; mains electricity; or LPG, in about that order of priority (but probably not all in the same installation!).
Clearly a fully integrated system is going to be fairly expensive and need some fairly sophisticated
controls, but with some very real benefits available.
This article is largely taken from the New Spirit Challenge award notice with additional information from Ian Bywater and Malcolm Souness
Biogas the New Power Source?
Biogas the New Power Source?
A Christchurch power engineer is developing technology that, in future, could see dairy sheds powered entirely by cow waste. Engenius Solutions’ Ian Bywater’s idea for asustainable system for cleaner dairying won the prestigious Institute of Electrical Engineers New Spirit Challenge Award, which rewards ideas for sustainability-oriented engineering projects, last year. Read More...