Sunday, July 23, 2017

Anaerobic Digestion of Manure Breakthorugh New Technology Raises Farm Throughput x 2!

Anaerobic Digestion of Manure: There has been a breakthrough in the throughput of manure-fed AD Plants! A new pre-treatment process development by Ductor™, raises new hope for super-efficient on-farm manure fed biogas plants.


The Problem With Anaerobic Digestion of Manure

Almost all organic materials such as manure are good feedstock materials for biogas production. Farm manures, from dairy manure, to chicken litter are available in abundance as a feedstock, but until now the AD Plants which process them have all suffered from a huge draw-back. The reactors have to be very large, because the fermentation process is very slow for these high Nitrogen (high-N) materials, and biogas production is low compared with other lower N feeds.

  This means that for on-farm manure anaerobic digestion to be economically viable only very large farms which can provide economy of scale can benefit from these large AD plants.

The Need for a Breakthrough in Manure AD Plant Productivity

Until now the (high-N) reactors have had to be very large, because the fermentation process is very slow for these high Nitrogen (high-N) materials. A breakthrough in AD process technology is needed to raise the throughput rate, and we know this is possible because every cow on the planet does it far more efficiently than any man made biogas reactor!

The Ductor™ Approach which Resulted in AD Plant Productivity Doubled In Tests

High-N materials hamper biogas production by inhibiting the bacteria in charge of breaking down organic material. So, Ductor's process designers said: "What if nitrogen could be separated from feedstock BEFORE biogas production?" So, they embarked on a research and development project to find a way to do just that. And, now this is possible, as a new approach to AD Plant process design using an additional fermentation stage to pre-treat feedstock, which has been developed in Finland by Ductor. This process is known as the Ductor™ fermentation technology, where feedstock is (currently) fermented for about five days to convert organic nitrogen into inorganic one, namely ammonia (NH3). Ammonia is then processed out from slurry by stripping it out and storing it in liquid form, which can be used as a raw material for fertilizer production. According to Ductor's website in a trial the ratio of output fertiliser was 115 tons of ammonium sulphate, and 640 tons of solid organic material (fibrous digestate).

The Benefits of Ductor Fermentation Technology

This approach brings three clear benefits:
  1. Nitrogen is separated from bulk material, which now becomes a phosphorous fertilizer, and if potassium hydroxide is used as the pH controlling agent, a P & K fertilizer.
  2. Nitrogen no longer hampers the main biogas process, and thus a higher efficiency can be achieved.
  3. The removal of nitrogen allows new, high N feedstock materials such as poultry manure.
So, it really is possible to select new methods and approaches, and thus recycle the nutrients in a more efficient way. A great benefit is that additional costs are more than compensated by the benefits brought in as side-effects such as improved biogas yield. However, subject to ABP Regulations compliance, the separated fertiliser (ammonium sulphate) can become a premium value product sold off-farm as a renewable chemical fertiliser for income, while the fibrous digestate is returned to the farm fields to provide fertiliser for the farm itself. Furthermore, it is understood that this process technology, which is very much still in its infancy, can be further developed for even better efficiency.

What Ductor Says About Their Fermentation Technology

"The biological method developed and patented by Ductor eliminates the nitrogen dilemma by turning problem waste into profitable recyclable goods. Fraunhofer UMSICHT has been supporting the development of Ductor™ technology for removing ammonia since 2013. “Here, the process principle and the results of the pilot plant in Helsinki were evaluated. From the results so far, it can be concluded that the technology will work,” says Joachim Krassowski, Group Manager of Energy Supply Systems at Fraunhofer UMSICHT. “The process development of DUCTOR, in my opinion, is very professional and has covered all the necessary steps, from laboratory tests to the development of a semi-industrial test facility, up to the first plant on an industrial scale which was erected in Tuorla." December 2016
via Revolutionary Technology

"The Ductor® solution has a global market"

"Removing 60% of nitrogen – before biogas fermentation – is a ground-breaking innovation for the biogas industry. This is done by adding one fermentation step, prior to biogas fermentation, and a nitrogen stripping unit. This solution opens up a variety of new possibilities for improving the biogas economy and nutrient recycling. Ductor™’s technology has a global market, since the demand for solutions to improve the profitability of biogas production is tremendous everywhere."
via Revolutionary Technology

A "Retro-fitting" Opportunity

At we see this process as a retro-fitting opportunity for existing AD plants that are possibly struggling to make a good profit from their current biogas output. Biogas producing businesses in that position may wish to investigate the economic viability of ammonia removal by pre-treatment for their existing biogas plants.

About Ductor™ Corporation:

Ductor™ is a company with a unique portfolio of proprietary and patented technology to improve waste management, energy, and food production. Ductor™ has developed a unique fermentation system that removes more than 60 per cent of nitrogen from organic waste before biogas fermentation. Last year, Ductor™ was awarded a GCCA TOP 10 prize in Taipei. Visit their website at:

Friday, July 21, 2017

Recycling Food Waste from Fish Morts Using Anaerobic Digestion

There are many sources of waste food, and ways to recycle food waste, but one of the most unusual must be to recycle fish morts by anaerobic digestion.

As the world's population continues to grow so will the amount of this type of waste grow, the main source of fish morts is from the aquaculture of fish, such as salmon and trout and that is very much a growth industry globally.

Therefore, it is quite likely that the anaerobic digestion of fish morts will become commonplace in the future.

 Fish morts are simply dead fish which have died during fisheries activites, but the fish that die during fish farming aquaculture activities are the main source which we will discuss here.

Watch our video about this below! Do you like to see these posts in video form? Please COMMENT to let us know your views.


Since the Animal By-Products (ABP) Regulations were introduced throughout Europe in the 1990s, it has been much more difficult to use fish mort waste in fishmeal and fish oil production.

In the past fish morts with their highly nutricious content were also used as an ingredient of pet foods, but again ABP Regulations and the concern that pet owner's may prefer not to give their pets any food derived from an unpleasant sounding source, have led to a decline.

Changes in the formulation of pet food products have also contributed. In addition, the old fall-back of landfill disposal is not only unsatisfactory to landfill owners who wish to reduce the organic matter sent to landfill (reduce possible landfill odours etc), but UK Landfill Tax makes it prohibitively costly.

Fish morts would preferably be incinerated if there are suitable facilities not too far away from their source, but again the cost is high. Just like any material which is more abundant than the market to use it, fish waste has little or no value.

It therefore, in principle makes a wonderful low-cost feedstock for anaerobic digestion, as long as the AD Plant is licenced to accept and process ABPs.

So, what could be better than to add it to the feed materials of a Scottish AD plant.

In the following Press Release it is explained how Landia, which is one of the world's leading manufacturers of chopper pumps, propeller mixers, aeration systems and advanced process equipment, is doing just that.

Fish Feedstock Used for AD as Landia Wins Important New Contract

Landia has been awarded an important new turnkey contract in Scotland to supply pumping, mixing, ensiling and pasteurization equipment for fish morts (food waste) that will be utilised as feedstock for an expanding AD plant. The 8m3 pasteurizer, which is fitted with Landia’s side-entry propeller mixer and equally robust dry-installed chopper pump will process the fish morts in accordance with ABP (Animal By-Products) regulations, fully approved by vets.

A 10m3 ensiling tank with an 18.5kW stainless steel long shaft chopper pump will also be designed, manufactured, installed and commissioned by Landia’s team of skilled engineers. This unit recirculates and blends the fish morts into a smooth purée, before being discharged into the pasteurizer. With the fish morts suitably mixed, pumped and pasteurized at 70 degrees Celcius by the Landia equipment, gas yields are forecast to increase significantly at the AD plant.
As well as its ensilers and pasteurizers, Landia also supplies the acclaimed GasMix AD digester mixing system and has just launched BioBuster, a new, non-pumping pre-treatment unit for AD feedstocks with high dry matter content. Engineered to last, Landia’s AD and food waste/fish processing waste equipment is based upon a wealth of experience, developed since the company’s first agricultural slurry pump when it began trading in 1933, going on to create the world’s first chopper pump in 1950. Tel: 0044 1948 661 200

Practicalities of Recycling Food Waste from Fish Morts Using Anaerobic Digestion

Wastes like fish waste (food waste) need to be macerated (chopped up) by pre-treating the fish morts waste before it is pumped into the biogas reactor.

In the example above, fish waste is pre-treated into a purée by the system before it is pumped into the biogas reactor, this requires the specialist equipment that only companies like Landia can provide.

 Food waste of this type is capable of producing high biogas yields, but to achieve this the viscous material needs to be well-mixed while in the biogas reactor, and this works best when specialist mixers are also used, such as the Landia GasMix.

Thursday, July 20, 2017

What is a Biogas Reactor

For those that ask "What is a biogas reactor" the definition we use is as follows:
 The biogas reactor within a biogas plant (anaerobic digestion plant) is the vessel or vessels in which anaerobic treatment technology produces two main products.

 These are:

(a) a digested slurry (digestate) that can be used as a fertilizer, and

 (b) biogas that can be used as an energy source.

Biogas is a mixture of methane, carbon dioxide and other trace gases which can be converted to heat, electricity or light.

Small-scale Biogas Reactors

Small-scale biogas reactors are typically designed to produce biogas at the household or community level in rural areas.

In most Small-scale biogas reactors the airtight reactors are buried in the ground and are filled with animal manure from the farm and house. Kitchen and garden wastes can also be added and toilets can directly be linked to the reactor for co-treatment of excreta.

Schematic of a small scale Biogas Reactor Large Commercial Scale

Biogas Reactors Although the process in large scale commercial biogas reactors is the same as in the small ones.

Large scale commercial biogas reactors vary from the digesters built to service a small farm (i. e. "small" in western terms) up to the digesters built to digest the sludge from a large sewage treatment works. In all cases the definition of the reactor is the same, although the majority of large scale biogas reactors are made from circular steel tanks, which are lagged for the necessary heat retention.

 A More Detailed Alternative Definition for "What is a Biogas Reactor" 

 A biogas reactor is an airtight chamber that facilitates the anaerobic degradation of blackwater, sludge, and/or biodegradable waste (e.g. animal manure, kitchen and garden wastes).

It also facilitates the collection of the biogas, a mixture of methane (CH4) and carbon dioxide (CO2) produced in the fermentation processes in the reactor. The gas forms in the slurry and collects at the top of the chamber, mixing the slurry as it rises.

 The pressure exerted by the rising gas can be used to transport the gas to the collection vessel or directly to where it is going to be used. The digestate is rich in organics and nutrients, almost odourless and pathogens are partly inactivated.

 Biogas Reactors Are Living Organisms: Operator Responses When Biogas Output Drops 

Biogas Reactors work well most of the time when the operator uses feedstocks with which the plant operator has experience, but when new feedstocks are introduced, or even when familiar feedstocks are used, the biogas quality and/ or quantity may drop. It is necessary to take action when the biological process shows signs of imbalance. In this context the operator has only a few options available at most AD plants.

The operator can reduce the feed rate, or cease feeding in which case the reactor may stabilise itself, dilute the biomass, or add fresh or degassed biomass to rectify an imbalance in reactor chemistry where the cause is known.

 Biogas Reactor feeding changes are an important tool to correct reactor slowdowns, but it is difficult to give a precise recipe for doing it successfully.

 Most biogas plants have, to a greater or lesser extent, been subjected to operational disturbances, and several plants have experienced that the process at worst may break completely.

Such collapse can have serious financial consequences for the plant, and Biogas Reactor chemistry problems are an issue that focuses the minds of all AD plant owning business men.

 Downward drifts in biogas output, and even a collapse in the biogas produced in a biogas reactor, are often linked to the types of biomass that the plants are fed with, and unfortunately it has been found that a combination of manure and other organic waste of varying strengths and composition, can become a dangerous cocktail.

 If there is a lot of protein and fat in the mixture in the reactor, it can cause high concentrations of ammonium and long chain fatty acids (LCFA) that may inhibit the process.

The best way to avoid such inhibitions is to have a thorough knowledge of the type of biomass that the plant is supplied, both in terms of the chemical composition and how the biomass breaks down in the plant.

 In addition, it is important to accurately measure the different types of waste entering a biogas reactor, as well as detailed process monitoring is very important.

 Unfortunately, it is far from always that the plants have the opportunity to feed consistently with the same types of feedstocks to provide the reactor with stable conditions.

The ability of the biogas plant operator to find consistent feedstocks are limited in number and size by the availability of materials, and the operators will therefore often be forced to mix.

 Those biogas plant which are fed from feedstock produced through the operators own business activities (e.g. on-farm manure) have the best chance of ensuring consistent feedstock availability.

 To provide a service for the disposal of organic (biomass) wastes for long-term clients makes the need to accept variations in the composition, quantity and delivery frequency of the different types of waste inevitable.

 This means that the plants may be forced to supply a certain type of waste to the biogas reactors at a time when it may cause problems with the stability of the biological process. Finally, a complete monitoring of all process parameters is a time-consuming and expensive solution, which means that monitoring at most plants is inadequate.

 As a consequence of these constraints, various drift disturbances occur at biogas plants. The question is therefore:

What can managers do to quickly restore the process when they detect a decline in gas production?

At the Department of Environment and Resources at the Technical University of Denmark they have conducted a series of trials to restore the biogas process in laboratory reactors.

The experiments supported by the Energy Research Program were primarily based on dilution of the biomass with either water, manure or degassed biomass.

 The process was inhibited by adding either ammonium or LCFA to four reactants with cattle gel.

he outcome of the different strategies as well as a description of the experiments are discussed below.

Ammonium Inhibition of Biogas Reactors

After inhibition with ammonium, it was found that the most effective method of recovery of the process was to replace half of the reactor content with degassed biomass or fresh cattle gel.

 With that strategy, it took about six days to return to the original gas production, while it took 10-11 days if 50 percent water was added instead or the daily amount of manure was reduced.

After almost six days, a significant increase in gas production was recorded in the reactor, which added 50 percent fresh cattle gel.

Thus, throughout the recovery period, this reactor produced between 42 and 74 percent more gas than the other reactors, which is associated with the additional amount of organic material that the reactor was supplied in the form of fresh slurry.

 However, one should also stick to the evolution of the oxygen level during the restoration, as it gives an indication of how stable the process is.

Here it was found that the increase in the acid level was somewhat higher by the addition of fresh manure than by the addition of degassed biomass.

Therefore,, much evidence suggests that the most effective and safe method of ammonium inhibition is a combined addition of manure and degassed biomass.

The worst approach is to do nothing and only add the daily amount of manure or dilute the biomass with water.

The supply of water provides a faster recovery than if it is not intervened, but on the other hand, this strategy leads to relatively low gas production.

 The strongest increase in oxygen levels was recorded in the reactor where no intervention was taken, indicating that the process here was more affected than in the other reactors.

 LCFA Inhibition

Inhibition of the biogas process by the administration of LCFA showed substantially the same picture as inhibition with ammonium. via

Monday, July 17, 2017

Anaerobic Digestion UK - Reduce Biogas Cost Raise Biogas Yield Improve Hydrolysis

The Anaerobic Digestion UK market should dramatically decrease biogas production price, and also produce a big improvement in digester returns elevating them by an unbelievable 20 times current norms.

That's the vision of some in the UK market, that also point out that without a revolution in AD innovation performance there is little chance of the biological fermentation process accomplishing its full potential.

What's more, they make the point that biogas works best as an energy storage tool, yet to earn a distinction large amounts of biogas have to be readily available to (for instance) balance electrical energy grids during maximum demand loadings.

The Anaerobic Digestion UK industry needs to drastically reduce biogas production cost, and bring about a revolution in digester yields raising them by an astonishing 20 fold.

That’s the vision of some in the UK industry, who also point out that without a revolution in AD technology productivity there is little chance of the process achieving its full potential.

What’s more they make the point that biogas works best as an energy storage medium, but to make a difference very large quantities of biogas need to be available to (for example) balance electricity grids during peak loadings.

Most anaerobic digestion UK commentators would say that the UK anaerobic digestion as a whole has been very successful in the last few years, starting from a low base the year on year rises in installed AD Plant capacity have been impressive.

Those involved in building the plants, have worked very hard and achieved a great deal, and may understandably be wringing their hands in disappointment to be told that actually they may not have reached far above base camp, and Everest is still there to climb.

However, that in effect is what is staring the UK anaerobic digestion industry in the face, and there are people who are very willing to take that reality in hand and accept the challenge.

One such is AD&Bioresources Association Member, Tropical Power. Below we repeat part of a recent foreword in their magazine, by Mike Mason, Chairman, Tropical Power.

We liked the piece so much that we also created a video on the subject below, for those that prefer to watch a video rather than read text:

Storing Up The Benefits Of AD


…If AD is to really deliver in those areas it needs to compete on cost with wind and solar – solar PV is achieving costs of £30-£50/MWh in places, with wind close behind. The first challenge for AD is therefore to drive down costs – not by 30 per cent but to one third or less of current levels.

That means serious, fundamental research leading to the revolutionary progress that is needed if the industry is to catch up with the rapidly falling costs of other technologies.

The clues that this might be achievable come from ruminants like cows, where the rate-limiting step of anaerobic digestion – hydrolysis of the cellulose – can take place up to 30 times faster than in an AD plant. Imitate this and the world of AD looks very different.

It speaks of plants built in factories as affordable machines, rather than in fields as expensive civil engineering projects.

But there is more to value than just cost. Storage is the energy world’s greatest challenge. Solar and wind cannot offer dispatchability, and batteries add perhaps £50-£60/MWh to the cost of delivering renewable electricity – doubling the cost of night-time solar. Storage is therefore AD’s ‘ace in the hole’.

Biogas is cheap to store, and larger engines are little more expensive than smaller ones, so AD can back up solar or wind and help stabilise struggling grids.

Perhaps the most important global role for low cost AD, therefore, is to be a key part of solving the critical storage and stability issues that future grids will face.

As well as driving down costs, we should be arguing for greater recognition of the value of our technology in a low carbon world.

Reducing Biogas Cost & Raising AD Yields 20 Fold  - The Technical Challenges 

There are two technological challenges which the anaerobic digestion industry faces, which if low-cost solutions can be found might go a long way to meeting the Tropical Power vision described above, and these are:

 a) Greatly improved hydrolysis of the cellulose content of all biomass feedstocks. In essence to replicate the speed in cows achieve hydrolysis in their stomachs.

If they can do it – why not man in his mechanical stomachs (biogas digesters)?

b) Finding a simple low cost solution to using those feedstock materials for biogas production which contain large quantities of nitrogen.

Such feedstocks are often avoided, because they may actually hamper biogas production by inhibiting the bacteria in charge of breaking down organic material.

A rate limiting factor in AD is the extent to which ammonia can be allowed to build-up within the process, before it inhibits growth of the organisms involved in biogas production.

Improving a) and b) would open the way to much higher yields of biogas per cubic metre of reactor volume.

If solutions to both of the above technological challenges were to be found which could be brought into widespread use, it would have a huge benefit to the take-up of AD, and go some way to making the “vision” we spoke of earlier, a reality.

To some extent solutions are already on the horizon. For a) there has already been thermal hydrolysis equipment on the market since CAMBI pioneered the concept as long as 20 years ago, and there are now many companies offering similar kit.

Other companies are also starting to offer enzymes for hydrolysing incoming cellulose, which looks promising.

For b) above there are fewer options, but one company is offering a process to separate nitrogen from high nitrogen feedstocks BEFORE biogas production.

They say that this is now possible, as a new approach using an additional fermentation stage to pre-treat feedstock. The technology has been EU funded, and has been developed in Finland by Ductor Corp. We will be writing an article about this interesting development soon.

Saturday, July 15, 2017

Anaerobic Digestion in UK Now Powers 1 Million Homes But Future Doubtful

In the UK anaerobic digestion capacity has grown rapidly to the point that the energy supply is large enough to have significance (and could power a million UK  homes if that was it's sole use), but unexpectedly steep government subsidy reduction has thrown the future of the industry back into doubt.

This was the overwhelming sentiment I was aware of during the combined AD&Biogas and World Biogas Expo 2017 earlier this month, when I visited many of the stands and spoke to many experts in the UK biogas industry.

While researching for this post I was struck by an article published at the start of July by the Anaerobic Digestion & Bioresources Association, which echoed these views so closely, that I have duplicated it in full here.

[If anyone at ADBA considers this use to be a copyright infringement, let me know - but the message seems so important that I hope they will support this use of their material.]

 AD Now Powers Over a Million Homes – New Report 

Originally Posted on 05 Jul, 2017 on ADBA News, by Chris Noyce 

A new report shows that anaerobic digestion (AD) plants across the UK now have enough capacity to power over a million homes.

The Anaerobic Digestion & Bioresources Association’s (ADBA’s) July 2017 Market Report is being launched this morning (Wednesday 5th July) at UK AD & Biogas and World Biogas Expo 2017, a global biogas trade show taking place 5-6 July at the NEC in Birmingham.

The report shows that AD in the UK now has a capacity of 730 MWe-e, an increase of 18% over this time last year, with total energy generation of 10.7 TWh per year.

Operational performance in the industry continues to improve, with load factors rising to 73% in 2016, up from 69% the previous year.

AD is currently reducing greenhouse gas emissions by 1% and employing more than 3,500 people in the UK, but with the right policy support has the potential to reduce emissions by 4% and employ 35,000 people.

Delays in the passing of legislation for the Renewable Heat Incentive (RHI), which is set to restore tariff levels to 5.35 p/kWh, has meant that there are currently at least 13 AD plants on hold.

Electricity generation from AD, meanwhile, is receiving next to no government support, with the Feed-In Tariff for >500 kW plants down to just over 2p/kWh.

50-80 new AD plants were commissioned in 2016 but this number is projected to fall to 19-64 in 2017 as a result of policy uncertainty.

 Commenting on the report, ADBA Chief Executive Charlotte Morton said:
"The fact that AD can now power over a million homes is a great milestone to achieve." 
"However, while it’s encouraging that the new Government has committed to the Paris Agreement and to meeting the UK’s Carbon Budgets, there is currently a desperate lack of long-term policy support for AD, particularly in heat and transport, areas where AD can make a significant contribution to decarbonisation." 
"While there are 437 AD plants in the planning stage, most of these are unlikely to be built without stronger government support for AD. This is a huge wasted opportunity – the Government needs to act now to provide both short and long-term certainty for the AD industry to enable it to deliver the green energy the Government urgently needs both to meet its legally binding climate change targets and for the UK’s energy security."

Chris Noyce, ADBA PR & Parliamentary Affairs Executive.

Read this and other articles at the ADBA website.

Thursday, July 06, 2017

Anaerobic Digestion: 10 Ways to Make Money from Biogas

#AnaerobicDigestion: 10 Ways to Make Money from #Biogas #renewableenergy

Did our Video Raise Your Interest in AD? If so carry on reading what others are saying about it, below:

Background Info on Anaerobic Digestion

The anaerobic digestion process provides at least 10 ways to make money from Biogas Plant, that's why it is such an amazing asset to the owners and operators of biogas plants. Once a farmer, for example, gets his or her own biogas plant up and running they soon realise that a digester is so much more than just a producer of renewable energy.

Generating heat and power from food waste and other organic waste is now well established. The principal is very simple. Waste is put in to a container without any oxygen and the microbes (bacteria) consume (eat) the waste which in turn produce methane gas. This is a natural process that goes on in peat bogs which is why methane is also known as marsh gas. The methane gas can be used to heat homes and other buildings, or even be sold to Butlins to heat their swimming pool. Alternatively the gas could be burned to drive a generator and produce electricity.

What better way to make money than to invest in a process which uses something that's normally thrown away?

Digester technology is a growing industry in a greener UK.'Recycle and re-use' is the mantra of environmentalists so it makes perfect sense that waste water and biodegradeable material can be processed into energy and fertiliser.

Anaerobic digestion needs to be on a certain scale in order to work; an individual cannot have a mini digestor in their back garden to create renewable energy. The sector is still in its infancy although more AD plants are on the way so the only way a private investor can invest in an AD plant is through a fund.

"It is an elegant and efficient way to access this sector, doing your bit for the environment whilst also looking forward to some healthy returns," Gudgin says.
via Americanbiogascouncil

What happens to food scraps after the city takes them? Soon a large fraction will wind up on Long Island, where Charles Vigliotti hopes to turn them into profit.

On an overcast winter morning, Charles Vigliotti, chief executive of American Organic Energy, drove me to his 62-acre lot in rural Yaphank, N.Y., 60 miles east of Manhattan, to show me his vision of the future of alternative energy.

He snaked his company Jeep around tall piles of wood chips, sandy loam and dead leaves. Then, with a sudden turn, we shot up the side of a 30-foot bluff of soil.

At the top, we gazed down upon those many piles and breathed in the mildly sulfurous exhalations of a nearby dump.

Vigliotti radiated enthusiasm.

Within the next several months, he expected to break ground — “right there,” he said, thrusting his index finger toward a two-acre clearing — on a massive $50 million anaerobic digester, a high-tech plant that would transform into clean energy a rich reserve that until recently has gone largely untapped: food waste. via

ADBA is the trade association for the anaerobic digestion (AD) industry in the UK and companies and organisations working on novel technologies and processes that compliment the anaerobic digestion process and products. With our members we promote the economic and environmental benefits of AD in the UK.

Anaerobic digestion is the simple, natural breakdown of organic matter into biogas (carbon dioxide and methane) and organic fertiliser called digestate. It is a similar process to that which takes place in the stomach of a cow. via

Anaerobic digesters are a mature, proven technology. They take sludge, manure, and other organic waste materials and produce methane (natural gas) fuel.

Nobody questions their technological capabilities. However, the question remains as to their economic benefits. In terms of dollars and cents, how much economic sense do anaerobic digesters make?

What are the economic benefits of an anaerobic digester fuel system? Under what scenarios do they make sense, and under what scenarios are they of only marginal benefit—or should not be considered at all?

As a source of renewable energy, how is this energy applied?

Can anaerobic digesters be used economically to provide grid-ready electrical power, or should they only be used to provide fuel for local, niche applications?  via

Many US wastewater treatment plants (WWTPs) are beginning to use anaerobic digesters to produce biogas that can be used in their combined heat and power plants to generate electricity and heat. In addition, the plants are selling the biogas into the gas grid. The growing interest in biogas has led to more attention paid to measuring biogas flow and composition, because proper gas engine operations depends upon use of biogas with the right methane (CH4) content. New ultrasonic technology, including the OPTISONIC 7300, developed by KROHNE, Inc., is being developed to provide the kind of reliable and accurate flow measurement needed to advance this important strategic energy source.

Over the past decade the U.S. has been taking a page out of Europe’s playbook by adding a spate of anaerobic digestion facilities to produce biogas, which can be can be recovered, treated, and used to generate energy in place of traditional fossil fuels. [1] Anaerobic digestion systems are used in a variety of settings, including wastewater treatment, food waste processing, and agricultural (manure) processing. via

Sunday, July 02, 2017

Farm Digesters And Reduction Of Greenhouse Gas Emissions

#biogas #anaerobicdigestion #climatechange

Farm Digesters And The Important Role of Biogas Reduction Of Greenhouse Gas Emissions

Agriculture is the largest source of methane emissions in Britain, adding the equivalent of over 17m tonnes of carbon dioxide to the atmosphere every year.

A very large proportion of that methane comes from livestock, especially cattle.

Anaerobic Digesters cannot prevent all those methane emissions. Some of the methane comes directly from the digestive systems of the animals themselves, especially ruminants such as cattle, by enteric fermentation.

But, AD Plants can reduce those emissions in a number of different ways.

  • They trap and use the large amounts of methane which would otherwise be produced naturally when raw slurry or farmyard manure is stored, or spread on the land. This prevents it from escaping into the atmosphere.
  • They allow the nutrients in livestock and other organic wastes to be more effectively used and recycled. This reduces the amount of fossil energy that is consumed, and therefore the greenhouse gases are given off, in the manufacture and transport of artificial fertilizer. (These emissions are in addition to the figure given above, of emissions relating directly to agriculture.) Recycling nutrients also helps, to some extent, to reduce emissions of nitrous oxide.
  • They produce a compost fibre which can help to reduce the use of peat in horticulture. This saves on the carbon dioxide emissions given off through peat extraction and use.

The difference between these overall savings in emissions, and those saved by generating electricity from gas produced by energy crops, instead of fossil fuels, is very significant.

This is a quotation from the book "Farm Digesters", by Jonathan Letcher.

Citations in support of these statements - again from the above book:

This is clearly illustrated by a bar chart produced by the German Energy Department.

The bar chartcompares the net emissions produced by generating lkWh of electricity using three different sources of energy. These are 1) an average of the fossil fuel types usually used for power generation in Germany (coal, natural gas, etc) 2) a digester running purely on specially grown energy crops, such as maize silage and 3) a digester running on a mixture of 40 per cent energy crops and 60 per cent livestock slurry.

The bar chart offsets actual emissions against reductions, if any, created by the process in question. A credit is given in the chart for reductions in the use of artificial fertilizer, for instance, or of methane and other emissions which would have been given off by slurry if it had not been processed in a digester. The results are very revealing.

In generating kWh, the averaged fossil fuels give off emissions equivalent to 0.7kg of carbon dioxide, while the energy crops produce net emissions of 0.45kg. The net emissions from the mixture of slurry and energy crops, by comparison, are less than 0.1kg. Unfortunately, the chart does not include a digester running on livestock waste alone.

But a new study by Bangor University6 estimates that generating 1 kWh of electricity from a digester processing cattle slurry alone reduces overall greenhouse gas emissions by the equivalent of 3.27 kg of Carbon Dioxide.

In other words, for each lkWh of output, the digester running purely on energy crops adds 0.45kg of carbon dioxide to the atmosphere, whereas a digester processing livestock waste alone reduces net greenhouse gas emissions by 3.27 kg C02e.

These figures show that processing livestock waste in a digester is a more effective way to of reducing greenhouse gas emissions than using energy crops alone.

That is the outcome even though energy crops produce more energy from a given size of digester.