Friday, March 28, 2014

Removing CO2 from Biogas - Carbon Dioxide Scrubbing Methods and the Eco Benefits from Upgrading to Eliminate CO2 from Biogas/53357d78cfee7
Biogas can be upgraded (purified) to natural gas distribution pipeline quality for use as a renewable natural gas, but as part of the upgrading process it will be necessary to remove the carbon dioxide (CO2) from the biogas. 

This upgraded gas may also be used for residential heating and as vehicle fuel, so there are many good reasons for removing the CO2. CO2 will always be found in biogas due to the fact that during anaerobic digestion, (i.e. degradation in the absence of oxygen), organic material is decomposed by bacteria forming a mixture of CO2 and CH4 with trace amounts of H2S and water vapour at saturation pressure. 

Common methods used to eliminate CO2 from biogas are: - water scrubbing - membrane systems - pressure swing adsorption (PSA) - chemical CO2 absorption - amine gas treatment - CO2 by cooling and recovering dry ice. These systems also generally reduce the H2S and H2O content. Biogas treatment systems, also need to include feed compression on the un-pressurized raw biogas.

Trace components that are often present in biogas are water vapor, hydrogen sulfide, siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide, and nitrogen. Pressure swing adsorption (PSA) systems, can be thought of as being molecular-sieves for carbon. PSA has been described are the second most commonly used biogas upgrading technology in Europe, after water scrubbing which is most likely the most popular. A typical system is composed of four vessels in series that are filled with adsorbent media which is capable of removing not only the CO2 but also water vapour, N2, and O2 from the biogas flow. 

Typically the PSA upgrading takes place over 4 phases: pressure build-up, adsorption, depressurization and regeneration. The pressure build-up occurs by equilibriating pressure with a vessel that is at depressurization stage. Final pressure build up occurs by injecting raw biogas. During adsorption, CO2, N2, and O2 are adsorbed by the media and the purified gas discharges as pure methane to a quality which will be far less corrosive and has a higher calorific value.

Recently developed gas-liquid membranes have been introduced, which operate at atmospheric pressures thereby reducing the energy consumption of compression. The use of specific solvent solutions allows the separation and recovery of the H2S and CO2.

 Another approach to improving the economics of gas upgrading has been to recover the CO2 by cooling and recovering dry ice. This can then be sold as an industrial gas whilst the biogas is either used in its more concentrated form (80-90% CH4) or further refined to vehicle quality standard (>96% CH4).

 An example of membrane use for the elimination of CO2 from Biogas follows:
"Silicone (PDMS) has a very high permeability to CO2 compared to methane. This difference in permeability facilitates the transfer of CO2 preferentially over methane, thus enabling the removal of CO2 from a natural gas stream.
Similarly other contaminants such as hydrogen sulfide (H2S) and water (H2O) can be readily removed from methane. The separation factor for CO2/CH4 is approximately 3 for a 50/50 gas mix, indicating that the ratio of the mass fraction of CO2 to CH4 in the feed/retentate is three times smaller than the ratio in the permeate.
Natural Gas purification is simple and straightforward. The feed gas is supplied to one side of the membrane though the feed port, and depending on the feed pressure, a vacuum supply to the opposite side of the membrane may be necessary at the permeate ports.
The contaminants with higher permeability than natural gas will permeate the membrane much faster than the methane, thereby stripping the feed from these contaminants. The high purity natural gas will exit at the permeate port. The permeate can be vented or flared as necessary."
Mongabay News, Pre Combustion CO2 Capture

Why It Is Green to Eliminate CO2 from Biogas?

The purification of biogas for higher value applications, such as vehicle use or pipeline-quality, is established to be in general a more sustainable and environmentally friendly option than conversion of the energy to electricity as the energy losses from power generation and the transmission losses for electricity are in general higher than for direct uses of the gas as fuel.

Also, the AD Process is uniquely able to produce transport fuels, whereas other renewable energy sources such as wind turbine, and hydro-power don't, which suggests that it is best utilized to meet the demand for transport fuels.

The energy efficiency for transport fuel use of upgraded biogas is particularly good where the upgraded gas is used to fuel vehicles working on the came facility, or operating from the same facility. The technology for biogas upgrading is relatively new and improvements to the upgrading processes are ongoing to reduce methane losses and improve energy efficiency.

Thursday, March 20, 2014

Cory’s First Anaerobic Digestion Plant Uses Landia GasMix System a Load of Rubbish! A Plea for sustainable waste disposal./532ac7a2e794a

Cory Environmental, who with over 40 sites are one of the UK's leading recycling, waste management and energy recovery companies, has unveiled its first anaerobic digestion facility, with Landia’s acclaimed GasMix system at the heart of the process.

 Generating up to 500kw of energy per hour for on-site use and export to the National Grid, Cory’s inaugural digester at Weston-Super-Mare has the capacity to handle 12,000 tonnes of food waste pa. Around 7,500 tonnes of this is part of a seven year waste treatment contract with North Somerset Council. Alistair Holl, Cory’s Director of Resource Management, said:
“We are very proud of our first AD facility, for which our team were main contractors, as well as plant and site designers, achieving energy production just 18 months after planning consent was gained. This includes us recognising the importance of a highly effective and ultra-reliable mixing system, which is why we’ve chosen Landia’s GasMix. It mixes the digester throughout at a consistent temperature, which will optimise our gas generation”.
He added:
“GasMix is mounted externally on the digester so routine maintenance can be carried out with no interruptions, and from our past experience with Landia, we also have peace of mind in the back up service that they provide”.
Sustainable waste management servicesFor over a decade, Landia’s Chopper Pumps have been installed at other Cory sites – and at Weston-super-Mare, they are also in use in eight other process and storage tanks, where they perform a combination of process mixing and transfer functions. Paul Davies, Landia’s UK & Eire Sales Manager commented:
“Our relationship with Cory has grown steadily over the years as we’ve worked together to adapt the best possible pumping and aeration solutions for their wastewater needs. We are very pleased to see the faith placed in us and our equipment, with our GasMix system set to play a long-term role in the success of this impressive new facility”. Alistair Holl continued: “Initially, we’ll be producing enough energy to power around 1,000 homes, and will soon be working towards the second phase of the development, which will see an upgrade of the plant to a minimum of 1MW. This will double the volume of our green energy generation at Weston-super-Mare”.

Comprising three 18.5kW chopper pumps and a self-aspirating system that reduces solids to produce more methane in a much shorter time period, Landia’s GasMix (designed specifically for AD/biogas) has no mechanical equipment inside the digester. Simple to regulate, GasMix also offers significant energy savings because it only has to run for a maximum of 30 per cent of the installed capacity.

 +44 (0) 1948 661 200

Saturday, February 08, 2014

The Anaerobic Digestion Processes Used For Municipal Solid Waste Diversion Away From Landfill And Biogas

Increasingly Anaerobic Digestion Processes are being Applied To Municipal Solid Waste (MSW) for the production of biogas as a renewable energy source, and also for Waste Diversion. Waste Diversion in this context means the diversion of waste (especially organic waste) away form landfill.

Anaerobic Digestion Processes
The Anaerobic Digestion Process Flow Diagram – Material and Energy

Anaerobic digestion (AD) of MSW is often part of an MBT Plant (Mechanical Biological Treatment Plant) and the AD process is applied to the organic fraction of the waste which is separated from the mixed residual waste which the householders place in their “black bag” and is known as residual waste. To start with the municipal solid waste feedstock is macerated (chopped up in specialized knifing equipment) with the addition of a large proportion of process water to provide either a dilute thin (‘wet’), or thick (‘dry’), slurry that can be fed into a digester tank. This stage also normally includes a useful decontamination stage to remove heavy and light contaminants through wet gravimetric (gravity based) separation.

The digestion process takes place in sealed tanks (digesters) that are normally mixed thoroughly using externally mounted pumps which pull the liquor out into the pump, which while returning it ejects it at speed again into the tank, or stiring blades, to maximise contact between microbes and waste. Mixing can also be achieved using the methane gas by pumping it out from the reservoir above the digestor reactor into the tank, and allowing it to bubble up to the surface to create a mixing effect.

The AD process can be operated at mesophilic (typically 30 – 40°C) or thermophilic (typically 50 – 60°C) temperatures (see Table). Dry Anaerobic Digestion processes work well in the thermophilic range of temperatures. Wet processes can be either mesophilic or thermophilic with the first being the most commonly adopted for MSW AD. The EU Animal By-Products Regulations (ABPR) (current at time of writing but in case of changes readers must check for themselves) require the pasteurization of MSW which is classed as a mixed source AD waste, to a standard method which ensures a temperature of 70°C for one hour. UK legislation has an alternative option which (at the time of writing) requires treatment for 57°C for 5 hours.
AD processes can be single step processes where all the waste is placed into a single digestion stage (biogas reactor tank) or multiple step processes.

Multiple step processes usually include a separate hydrolysis stage, which can be either aerobic or anaerobic. Hydrolysis (heating to a high temperature and raising the pressure) is used to optimize the breakdown of complex organic material into soluble compounds. This is most often followed by a high-rate AD process for biogas production. The AD process can take place in a number of vessels, or just one, but normally two are employed, one as a hydrolysis vessel and the second as the digester.

An example would be to use thermal hydrolysis of the organic content of MSW followed by anaerobic digestion to produce a biogas that is burnt in an engine electricity generator set. The reason for using a hydrolyser, is the addition of this process stage results in more of the degradable material in the feed being converted into biogas, rather than just passing through and emerging in the digestate.

The key process stages which would be seen in the waste processing plant (MBT Plant or MRF) include an MSW reception area, shredding, and a form of wet separator, where the biodegradable material is separated from the inert and reject (sometimes called “contrary”) material. A thermal hydrolysis stage is a feature of many MSW biogas process systems, followed by a one stage anaerobic digestion process.

The AD plant utilizes the biogas produced is often used to power an engine, which powers a generator, with waste heat recovery that delivers the steam and heat to the hydrolyser and digesters.

Anaerobic Digestion Processes – Commonly Considered Process Options

Anaerobic Digestion Process Option Diagram - Anaerobic Digestion Processes
Anaerobic Digestion Process Option Diagram

It is accepted by many AD professionals that the rate-controlling step in the anaerobic digestion of MSW is the hydrolysis of complex materials such as cellulose, in paper and leaves etc. in the waste. The process converts the waste into small soluble molecules such as glucose, which can then be easily digested by the biogas producing microbes. In the commercially available process this conversion is accelerated by heating the material under pressure to around 150°C. This results in substantially more of the biodegradable material being made available for conversion into gas and ensures the feed material is also sterilized, as required by the EU Animal By-Products Regulations.

After this initial anaerobic composting period (when there is biogas production) the raw compost is placed in windrows (often out in the open) to mature for an additional 5-6 weeks, in the same way as for aerobic composting treatment. The matured compost is then passed through a trommell screen to remove any plastics.

In a final processing step to produce a digestate product for sale, the compost can be blended with additives (e.g. sand, brick dust). Plus, Nitrogen, Phosphorus and Potassium) can be added to meet different specifications from wholesale and retail sellers, and bagged if required.

Monday, January 13, 2014

What is TEEP and How to Comply? Was the Big Question at UK LWARB Event

TEEP cartoon
There has been a tangible feeling concern developing within the UK's waste collection and handling industry this last few months. In the main, the cause has been the thinking behind a new acronym that adds to the European’s ever increasing "waste glossary". 

 The abbreviation is "TEEP", and it refers to "technically, environmentally and economically practicable" requirements of operating standards for recycling collection systems. It has emerged as an important new requirement embodied within the EU’s Revised Waste Framework Directive (rWFD) which must be adhered to by European waste collection authorities and delivered by their contractors."

 The LRS Consultancy hosted the UK LWARB Event, which was the first high-profile UK event to pick up on the new legislative requirements, and they have explained in an article in the CIWM that they were responding to requests from their clients for information on the subject. Wayne Hubbard, chief operating officer, LWARB event said about TEEP that:
"It seems there has been overwhelming tension and anxiety about TEEP with no outlet or easily accessible information to date".
The event was apparently well attended and acted as a forum for local authorities and the resource management industry to listen to keynote speakers, and discuss the future of their recycling services when they will be complying with the new legal requirements for TEEP compliance. If TEEP is to have real value in enhancing sustainability within the waste management industry in Europe it will need work in a manner which will support the circular economy. The intent is that it should do this through ensured improved material quality emanating from the member nation’s collection, transport, and waste processing/ recycling industries.

So What Exactly is TEEP?

The European Union's Revised Waste Framework Directive (rWFD) includes a requirement to set up separate collections of the following as a minimum: paper, metal, plastic and glass, from the household waste stream by 2015. Article 11 of the rWFD states that "Member states shall take measures to promote high quality recycling and, to this end, shall set up separate collections of waste where technically, environmentally and economically practicable and appropriate to meet the necessary quality standards for the relevant recycling sectors."

 At the UK LWARB Event “feathers were ruffled” to a certain extent by the fact that time to implement is by anyone’s estimation really short, and once imposed in January 2015, the regulations will be enforced by the Environment Agency. Those in charge would have to be extremely diligent in adhering to the concept of TEEP as non-compliance might possibly lead to criminal prosecution. It seems that the concern is that at this time there is a lot of work to be done to establish what will be compliant when TEEP assessments are made.

The view appears to be that the decision as to whether compliance with the rWFD requires separate collections as opposed to commingling will rest upon interpretation of the TEEP rules, and an exercise of judgement. That judgement will not be clear-cut as it will need to balance technical, economic and environmental considerations in each waste management site’s, specific circumstances.

With that in mind it is not surprising that all waste professionals involved will find it hard to rest until through industry discussions and legal advice, the TEEP requirements can be crystallized into some form of good practice guidance which the professionals involved can rely on as a fall back to support their waste collection and transport policy decisions. The LRS Consultancy Article in the January 2014 edition of the CIWM Journal gives the LRS view on the emerging industry wide opinion, as follows:
“TEEP requirements may provide many challenges for everybody along the supply chain and it is evident that there are no right or wrong answers. Indeed, there are rumors that any further definitive stance may only arise after the first legal challenge completes.”
The article suggests that Defra ministers will be giving further consideration to whether additional information or guidance is required, but the view on exactly what is needed seems to be somewhat fragmented with some local authorities wanting structured guidance and advice, while others may be of the opinion that they can decide how best to proceed on their own. LRS indicates that they will continue in their current role;
"as a catalyst to sharing knowledge and facilitating connections, and positive change enables LRS to understand the views from along the supply chain".
Meanwhile, LRS is offering their own suggested list of actions for local authority officers, and those involved in the supply chain. The first action they proposed is that Councils: "Get TEEP on to your risk register. Some councils are currently scoring this at the highest possible risk level on their register. It's appreciated, however, that new policy decisions are very unlikely ahead of elections next year."
The financial aspects of TEEP implementation will be central to the thoughts of Council officers at this time of expenditure cuts: According to the LRS, CIWM article:
"Jamie Blake, director of public realm, London Borough of Tower Hamlets said: "Local authorities find themselves having the most amount of money taken out of their budgets in recent memory. We are halfway through a six-year programme of service reductions, after which most authorities will have reduced their budgets by over 45 percent. Many authorities will find during their assessments that adding in separate glass collection, for example, will be very costly and highly disruptive to services and, therefore, clearly not economically practicable, particularly within an existing contract.""
Given the availability of initial council staff time to work through the changes TEEP implies for many, TEEP can be seen positively as a catalyst to review long-term strategies, and by improving processed waste material quality bring another step-change toward a vibrant circular economy. TEEP, when viewed with a healthy dose of optimism could also provide the push needed to end stagnating recycling rates, and capture more materials beneficially, while adding value from these materials through better quality. Whether it will, when both finances and council staff resources are as pressed in the UK as they uniquely are by the deep cut-backs in progress through 2014/15, and at such short notice of implementation, must surely be an open question.

Tuesday, December 10, 2013

Assessing Anaerobic Digester Cost for On-Farm Manure Management Projects

For the right farm business or operator of any process which produces as a by-product a consistent organic waste, an anaerobic digester producing biogas coupled to a generator, can be an excellent long-term investment. The methane biogas will cost less as a fuel than a diesel generator or a standard natural gas generator.

The best examples of implementing an anaerobic digester can mean a facility pays nothing for fuel. Facilities that need to replace a life-expired genset should consider all options, and include a biogas digester model within their energy options.

The decision should ultimately be based on what works best for a particular site and operator when the balance between investment risk incurred by adopting an Anaerobic Digestion process, against the benefits.

But, unfortunately, finding anaerobic digestion cost data to help put a price to the power over a set payback period is as hard as ever.

Government Bodies Who Provide Information on Anaerobic Digestion Costs

Looking to Government Bodies Who Provide Information on their view on Anaerobic Digestion costs, does not prove very productive, nor does it lead to any help with in-depth cost analysis.

We concentrated on finding costs for so called "manure management" biogas plants, and we did find the following statements:
Cost estimates for installing anaerobic digester systems [given here] have been based on manure-fed on-farm digesters. The estimated cost for a digester alone is between $400 and $700 per 1000 pounds of livestock weight to install. For dairy farms producing electricity, the installed cost is estimated at $800 to $1200 per cow for anaerobic digester system installation. The engine-generator can be up to half the cost of the project. Besides installation, it is important to consider insurance, operation and maintenance costs. Annual operation and maintenance costs can range from $11,000 for a small digester to $51,000 for a large system. The U.S. E.P.A.’s AgSTAR program has advised that anaerobic digester installation may not be economical for farms with less than 500 animal units (an animal unit is defined as 1000 pounds live weight), based on energy payback and using solids for bedding or selling as a soil amendment. If generating electricity, the electricity purchase price will have a large influence on the payback rate. Most systems can not be justified on producing electricity alone. Avoided costs of using digested solids as bedding and off setting some heating costs are usually necessary to justify the investment. As anaerobic digester technology continues to improve, it may become more feasible to install anaerobic digester systems on smaller farms. An anaerobic digester system does not run itself, it is not self-maintaining. [There are additional costs.] The system requires continuous monitoring, which is often done using computer-operated sensors. An anaerobic digester system requires temperature and pH regulation, as well as feedstock consistency. It will usually require 30 minutes to an hour per day to make adjustments and perform maintenance. Most systems that have failed were in part because of a lack of oversight and a person to champion the system. Agstar Themselves Say:
The profitability of a biogas digester depends on the size of the operation, the method of manure management and local energy costs. According to AgSTAR, biogas recovery can be profitable and most effective at existing operations of at least 500 cows or 2,000 swine. Manure should be collected frequently (at least once a week) in a liquid, slurry or semi-solid state. Any electricity that is not used on-site can usually be sold to the local utility. and Agstar also provides the following table of manure management anaerobic digestion costs: Table of Costs for Farm Manure Biodigester In addition to the above we have found some examples of press releases which provide at least some indication of the cost of their Anaerobic Digestion Plants, and may be worth reading in full to find information about individual biogas project costs.
The small city of Junction City is home to Oregon's first anaerobic digester, at the family-owned and run Lochmead Farms. Although not an incredibly new technology, Lochmead Farms, a dairy producer, is truly a frontrunner in green dairy technology in Oregon. The digester captures methane gas from cow manure and burns it in a turbine to create power. The anaerobic digester cost $2.2 million and was built by Revolution Energy Solutions of Washington, D.C. The digester creates 1.5 million kilowatt-hours of electricity, enough to power 300 homes each year. So much energy is produced that there is enough to sell some to a local public utility. The dairy farm itself, which was founded in 1941, has been at the cutting edge in alternative energy sources as well as local food and vertical business integration. The farm is building solar panels and produces 80 percent of the hay for its dairy cows.
On 26th August 2013, the second biogas plant at the Viessmann Company’s headquarters in Allendorf (Eder) was inaugurated. The first biogas plant went into operation three years ago. The new wet fermentation plant built by its subsidiary, Schmack Biogas, cost around €7 million. The biogas plant produces 1.5 million cubic metres of biogas annually, enough to provide about 1,650 households with electricity and 370 households with heat. ...biogas+cost?

This article has so far, we freely admit, not yet provided an abundance of data on the cost of anaerobic digestion (biogas) digesters for manure management.

We thought this while writing and tried searching for "anaerobic digester calculator" by using the Google search engine, and while wondering whether our readers might be able to calculate their costs that way we discovered that such calculators do exist. First, we found an interactive Excel spreadsheet calculator.

This one is an alternative method for assessing the viability of an on-farm biogas digester, and is available to members of the National Non-Food Crops Centre (NNFC} which you can join for a charge. There are two membership levels and the cost of these starts at just £80 + VAT (UK Pounds).

Follow the link below for more information:

 Other biogas digester cost calculators are also available at: and

Friday, November 08, 2013

What is Biogas and How Has It Been Hijacked?

The term 'biogas' is commonly used to refer to a gas which has been produced by the biological breakdown of organic matter in the absence of oxygen. The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen and the resultant energy release allows biogas to be used as a fuel. In the same way that ethanol and biodiesel have been around for a long time, biogas has a long history. Back in the 13th century, explorer Marco Polo noted that the Chinese used covered sewage tanks to generate power. The author of Robinson Crusoe - Daniel Defoe  – referred to biogas technologies back in the 17th century. Biogas has been used widely in the UK for centuries and back in 1895, the city of Exeter used gas from sewage to power its city street lamps. According to its composition, biogas presents characteristics interesting to compare with natural gas and propane. Biogas is a gas appreciably lighter than air, it produces twice as less calories by combustion with equal volume of natural gas.

Biogas is Awesome!

Biogas is also known as biomethane (when further purified and compressed), swamp gas, landfill gas, or digester gas—is the gaseous product of anaerobic digestion (decomposition without oxygen) of organic matter. In addition to providing electricity and heat, biogas is useful as a vehicle fuel. When processed to purity standards, biogas is called renewable natural gas and can substitute for natural gas as an alternative fuel for natural gas vehicles. The gas has a composition which is usually 50% to 80% methane and 20% to 50% carbon dioxide with traces of gases such as hydrogen, carbon monoxide, and nitrogen. In contrast, natural gas is usually more than 70% methane with most of the rest being other hydrocarbons (such as propane and butane) and traces of carbon dioxide and other contaminants.

What is Biogas - Its "one of the most untapped sources of natural and sustainable energy available"

Biogas is one of the most untapped sources of natural and sustainable energy available. It is used all over the world and by far the largest number of biogas plant (technically known as anaerobic digestion plants) are relatively small installations and are found in the developing nations. India for instance has more than 12 million digesters). The Africa Biogas Partnership Programme (ABPP) 70,000 biogas plants in Ethiopia, Kenya, Tanzania, Uganda, Senegal and Burkina Faso. That project alone will be expected to be providing about half a million people access to a sustainable source of energy by this year 2013. Biogas plants can be useful resources wherever you are. An example of this is the Mount Everest area. It is a destination for climbers and trekkers from all over the world. While visiting our world’s highest mountain, climbers, trekkers, and walkers take away great memories, lots of photos and new friends, but leave behind their untreated waste. At the Mount Everest Biogas Project they are going to convert human waste from base camp into environmentally safe products for the people of Nepal, by designing a biogas system that can operate at high altitudes (above 5000 meters / 16,400 feet) above sea level. The area is the home to the summit peaks of Mt. Everest, Pumori, Lhotse and Nupste. The base camps for Everest and the other peaks in Sagarmatha National Park, Nepal are the expeditions’ summit climb beginning. These base camps host the climbers for weeks as they prepare physically and mentally for the challenge ahead. These camps have also, over the years, been scarred by human impact. With so many people in such a limited space, the challenge of limiting pollution due to human waste has persisted. Anaerobic digestion is unique in its ability to reduce the impact of visitors by providing biogas as a cooking fuel, which reducing the need for the local people to denude the local tree growth to heat their food and eat.

The Future for Biogas Lies With a Domestic Biogas Plant Revolution in the West

That is a measure of how both humble in its nature, but capable of healing nature, anaerobic digestion can be.

But, there needs to be a revolution in its use so that the western world can reap the same benefits as the east has done at a domestic level. The west needs to tap it's own domestic waste for renewable energy and home biogas plants offer a 100% natural way to do this.

Clean-burning biogas at home from ordinary kitchen and garden waste is the future. Biogas generates more energy than solar panels anytime day or night, rain or shine at a fraction of the cost.

And unlike solar panels, biogas provides excellent cooking fuel and high-quality nitrogen-rich fertilizer for gardening or landscaping. Biogas is a mixture of gases composed largely of methane produced during the natural decomposition of organic matter. Home and small farm biogas systems are simple as 1-2-3 to operate and biogas can be used for anything fossil natural gas can, including cooking, running generators and pumps and even vehicle fuel.

Biogas for the Future

The possibilities of increased use of anaerobic digestion as an effluent treatment process depend upon the introduction of improved small scale and particularly domestic scale reactor designs. However, there are critical factors influencing the economic use of the process which still need to be addressed in the context of use of AD in the home in the industrialized and wealthy west. The choice of better digester designs is therefore essential in relation to the waste itself, and problems in its supply, and handling and transportation of the end product from urban households will need to be solved. Limitations concerning thermodynamic efficiency, scrubbing costs, flammability, compressibility and storage are also hampering home use of biogas plants. Communities and governments throughout the west should be investing heavily in the development of new small scale anaerobic digestion system technologies with the vision of making them as common as the domestic washing machine and dishwasher is today. Then the west would benefit from this amazing technology just as the east is already is. Why is the west so lacking in vision?

"AD in the west has been hijacked by big business"

Surely, the west is being left behind with so few domestic scale AD Plants? They work massively in the developing world so why not in the west? The fact is that unfortunately in the west we all think of big corporations when we think of biogas, and we are missing the point. Biogas works best at the small scale. Why don't the developed nations realize this? We are all blind to this because, AD in the west has been hijacked by big business. It has been stolen from the average person. This isn't right!

What is its Future?

All people in the developed nations should go out and demand government support and investment in their own anaerobic digestion plants in their own homes. Anything less flies against all the evidence. As we have already explained. They can do it in India, Ethiopia, Kenya, Tanzania, Uganda, Senegal and Burkina Faso. So why not here in the developed world as well?

For more detailed technical information we suggest you download the excellent factsheet at:

Originally at: the AD Blogsite article here.

Wednesday, October 30, 2013

Latest News in the Anaerobic Digestion of Dairy Manure

In order to pick up the skills needed to take the plunge and invest in anaerobic digestion technology on any farm a degree in the subject is not essential, but having one and being fresh out of college clearly helps, as in our first news item, which follows:

(Image by Michael J. Linden via Flickr.)
Armed with a master’s degree in animal science, Vanderkooi opened the 80-acre farm near Abbotsford, British Columbia, in June of 2010. He has since established himself as a pioneer among small-scale, sustainable farm owners.
An anaerobic digester is one of the key technologies that Vanderkooi uses in his quest to reduce his farm’s ecological footprint. This machine turns the methane gas released from cow manure into electricity. About 65 percent of cow manure is composed of methane, making it an abundant energy resource. Over the course of a year, Bakerview EcoDairy is able to offset a third of the energy needed to operate the farm, thanks to the digester and a small herd of 50 cows.
Harnessing The Hidden Power of Cow Manure | QUEST
The anaerobic digestion of dairy manure was in the news again when we are told that "manure makes heat", but not initially by anaerobic digestion. Here is a novel idea for gaining heat from a compsting pile, and we cite the following in order to explain:

The pile consists of layers of cow manure and hay embedded with temperature probes, Crockenberg said. It is also negatively aerated, meaning that it draws in air through the pile into the greenhouse, he said.
The goal of the pile is to provide CO2 and heat to tomatoes growing inside the greenhouse. This would mean that no fossil fuels would be needed to heat the house in the winter.
But the energy has to come from somewhere. That is where the manure comes in.
By providing the organic material for the microbes to feast on, the cow manure is the source of heat and nutrients for the plants.
“The pile takes in manure and other organic wastes as an energy source,” Cooke said. “It kills two birds with one stone. The farmers can dispose of manure and heat the greenhouse.”
Later, however, we are told that this is only part of the project which will include:
"...anaerobic digestion, solar powered technology, aquaponic fish and vegetable production, gourmet mushrooms, a restaurant, nano-brewery and access to the future skate park and marina, a May Cynic article stated."
Manure makes heat - Vermont Cynic

Clearly, there is plenty of news about projects involving the anaerobic digestion of dairy manure currently in the US. More snippets are:
A 10-year effort has come to fruition for a local business. On Monday, A1 Organics in Eaton — the region’s largest commercial composting and organic recycling company — announced it had entered an agreement, worth tens of millions of dollars, with a renewable energy business to develop what could be the largest anaerobic digester project in the U.S. The anaerobic digestion system will convert organic feedstock, or substrate, and dairy cow manure into raw biogas. That raw biogas will be processed into pipeline-quality renewable natural gas, and then be supplied to a municipality.
Eaton business developing state's first anaerobic digester to convert manure ... - Greeley Tribune

Dane County’s first manure digester, which began operation in 2011, is located in rural Dane at 6321 Cuba Valley Road — that’s in the town of Vienna just north of Waunakee.
It serves three farms and is estimated to produce about 16 million kilowatt hours of electricity annually, enough to power approximately 2,500 homes.
A second digester, which is scheduled to be completed later this year, is located just west of the corner of Church Road and Schneider Road in the town of Springfield, west of Middleton. It also serves three farms and is expected to produce the same amount of electricity.
County Executive Joe Parisi’s 2014 budget includes a couple of additional items for the Springfield digester. It will include a system that removes 100 percent of the phosphorus, which is responsible for causing algae growth in the Yahara chain of lakes.
It also will include a drop-off facility for other farmers to bring loads of manure as an alternative to spreading during poor runoff conditions.

Just Ask Us: Where are Dane County's manure digesters located? -