Poultry manure to power in the Darling Downs

Poultry manure to power in the Darling Downs

Darling Downs Fresh Eggs is the first Australian egg producer, and one of only a few in the world, to power its business using renewable energy generated from poultry manure.

The company expects to reduce its grid electricity usage by 60% in the first year, saving around $250,000.

[December 2014]

Key points
  • The company has proven that renewable energy can be created from poultry manure using the process of anaerobic digestion.
  • The renewable energy will satisfy most of the company’s energy requirements in non-peak periods and reduce its grid electricity usage by 60% in the first year.
  • Using excess heat from the generator, the company will heat water for warming the rearing sheds and washing the eggs, thereby halving its LPG usage.

About the company

In December 2014, Darling Downs Fresh Eggs became the first Australian egg producer to power its business using renewable energy generated from poultry manure.

An anaerobic digester converts the chicken manure to biogas, and a generator converts the biogas to electricity.

At the time of writing, the digester was fully operational and the electricity generation had been going for about 2 weeks.

Located about 40 kilometres south-east of Toowoomba in Queensland, Darling Downs Fresh Eggs produces about 6 million dozen eggs a year, supplying both domestic and international markets.

The family-owned business began as a free-range farm about 40 years ago but since 2000 its focus has been caged hens.

The operation includes rearing hens from 1-day old; grading, packaging and distributing the eggs; and milling stockfeed onsite.

It’s a modern enterprise where everything is automated. Technical Manager Chris Adams can control the entire operation from his mobile phone.

A waste problem

The 130 tonnes of chicken manure produced every week by the 390,000 hens, a resource which is now powering the farm, was once an issue for the business.

“We used to stockpile the manure and sell it to neighbouring farmers who spread it on their cultivation”, says CEO Geoff Sondergeld. “But we didn’t get much for it and the family is conscious of its environment footprint, so we decided to look for alternatives.”

One of the 106-metre-long chicken sheds
Disposing of the 130 tonnes of chicken manure produced every week by the 390,000 hens was once a problem for the business.

Waste water from the grading floor also has to be disposed of. The grading floor is where the eggs are sorted by size, inspected for cracks, washed, stamped and packed into boxes. This waste water was previously fed into temporary evaporation ponds along with the reject water from the onsite filtration plant.

The filtration plant uses reverse osmosis to filter the local bore water to provide drinking water for the chickens, which drink up to 60,000 litres a day. One third of the bore water—up to 24,000 litres a day—is rejected and this water is high in salt.

Other organic waste includes broken eggs and hens that are no longer laying.

All of this waste is now being used to generate electricity.

Rising electricity costs

While waste was becoming a concern, even more worrying was the rising cost of electricity, especially as the family wanted to expand the business.

Egg production is power-intensive. The 100-metre-long sheds where the chickens are housed are kept at a constant temperature during winter and summer. And the day-old chicks need to be kept at a constant 36 degrees until they are 5 or 6 weeks old.

The business consumes almost a megawatt of electricity which costs many hundreds of thousands of dollars a year.

“In 2011, our electricity costs were rising 25% to 30% year on year”, says Geoff. “Some of that was volume related as we got bigger, but some of it was just pure cost in cents per kilowatt hour.”

The family knew they had a fuel source in chicken manure. They just needed a way of converting it to gas, which they could then use to generate electricity.

Generating electricity from poultry manure – why anaerobic digestion?

In 2011, Chris did a lot of research on the technologies that could potentially convert chicken manure to gas.

At the time, plenty of Australian piggeries were using anaerobic digestion to convert their effluent to biogas, but no-one in the poultry business was doing it, he says.

Anaerobic digestion uses microorganisms to decompose the biomass, producing gas comprising mostly methane and carbon dioxide. The gas is captured and converted to electricity.

“There are other technologies out there, but they’re 10 times the cost and 10 times as complex”, says Chris. “We needed something that we could put on the farm and that we could all understand it to a reasonable extent; something simple to use that produces the same quantity of gas.”

Meanwhile Geoff, through AusIndustry, was introduced to a number of farmers in the US who were using anaerobic digestion to convert waste to electricity.

“After some preliminary investigations, we jumped on a plane to have a look at how it was being done in the US”, says Geoff.

“What we saw was a combination of poultry and piggery operations using anaerobic digestion, but none of the sites we visited were 100% poultry. So there was still quite a degree of risk associated with it.

“We talked to farmers on the ground there who’d had these installations for 15 or 20 years. We picked their brains and their learnings, and that helped us challenge our own assumptions. And it helped us understand that it could actually be done.”

For Chris, the trip to the US verified the research he had done. “We probably saw 10 different digesters on 10 different farms, all over America. Some have been running for 2 years, some 10, some 15, and they’re all still sustainable and working.”

From a business point of view, Geoff could see significant benefits of using anaerobic digestion.

“It wasn’t a decision that we took lightly because there’s other things we could have done with that investment. But we had an available fuel source, we had the land, and it slotted into our framework quite nicely. And in the end the economics were fairly compelling.

“Then it was a question of whether we were prepared to take the risk. Because if it went wrong we had a great playground for the kids but nothing else.”

Chris and Geoff walk by the digester.
The 60 m X 60 m digester has a concrete base and is lined and covered with high density polyethylene.

Benefits to the business

The anaerobic digester, which is where the manure is converted to gas, was commissioned in mid-2014 and the first of the gas was converted to electricity in December 2014.

The obvious benefit to the business is lower electricity costs.

“We’ll save in excess of a quarter of a million dollars in year one”, says Geoff. “And there’s a whole host of other operating benefits.”

The business now has a clear management plan for all waste produced onsite. All of the liquids and solids produced are being reused in some capacity.

With no manure stockpile, there is minimal odour on site, says Geoff, which is good for staff, for the local community and for the environment.

Fully automating the collection of manure from the sheds to the digester speeds up the operation.

And by capturing methane from the manure, the business will reduce its greenhouse gas emissions.

“We’ll abate over 6000 tonnes of equivalent greenhouse gases”, says Geoff. “ So we’ll essentially be an environmentally sustainable business and that was fundamental to our business values and the family’s values.“

In 2015, they plan to also capture the excess heat produced from the generator and use it to pre-heat the sheds, topping it up with LPG. This will halve their LPG usage.


Funding the project was a challenge, says Geoff, given the risk associated with being the first in Australia to convert poultry manure to gas.

The capital cost of $2.86 million is funded by several parties:

“We were able to spread the risk and everybody felt comfortable with the position that they’ve taken”, says Geoff. “We were clear about what the investment was going to deliver, very robust around our assumptions, and very clear about the benefit we would derive.”

Pitching the project to potential investors was not a simple process and required a lot of analysis, he adds. For example, they had to model a year of their electricity usage in 30-minute increments, with different scenarios for pricing, consumption and load-balancing.

“NAB Agribusiness were outstanding”, says Geoff. “They had a renewable energy specialist in their team who knew everything about anaerobic digestion, so he was able to provide support to the bankers who were crunching the numbers so we could balance the risk and financial aspects of the investment.

“AusIndustry in Brisbane were fantastic in guiding us through the process of getting the federal government grant.

“The CEFC helped us immensely in terms of getting enough funding, but also in balancing the risks for the NAB, for the CEFC and for ourselves, because we’ve put in a substantial amount of our own money as well.

“So everybody had a fair degree of skin in the game.”

Geoff’s tips for dealing with funding agencies
  • In the business case, have a very detailed scope of works that shows you know what you’re purchasing, what’s in and out of scope, and what your investment is.
  • Be very clear about the benefits that you’re going to achieve. Include only those benefits that you can clearly articulate and put a hard number on.
  • Be robust in your assumptions and be very clear about those assumptions.
  • Be very clear about the design of the plant, and really challenge yourself before you go and talk to funding agencies.

Capital costs and payback period

Cost savings
  • Total project cost: $2.86 million
  • Projected cost savings on electricity and LPG in year one: more than $250,000
  • Expected payback period (when the total project benefits are considered): 5–7 years.

Designing the system

The whole system was designed and built by RCM International who managed the gas production and Quantum Power who managed the electricity generation.

“Quantum is a strategic partner of the CEFC, so they approached us”, says Geoff. “And RCM International, they’ve got digesters all over the world. We did a lot of due diligence on Quantum, we did a lot of due diligence on RCM, and hence the visit to America. Chris challenged their designs, so we were clear about how that design would work in the context of the rest of the business.”

One of the family’s stipulations was that the design of the system would not substantially change how the business operates.

“We didn’t want to change diets and feed and our existing operations”, says Geoff. “So that process of producing an egg remains the same today as it was 24 months ago.”

How the system works

“It’s a simple process”, says Chris. “You mix the manure with water to make a slurry. You put the slurry into the digester where it sits for up to 30 days and is mixed regularly. It produces methane. The methane is captured and pumped into an engine, which is basically a gas-driven generator, and it produces power.”

A simple system

The digester is a 60-metre by 60-metre hole in the ground, located about 100 metres from the chicken sheds. It has a concrete base and is lined and covered with high density polyethylene. From the water level down, it is 6 metres deep and holds about 10 million litres of fluid.

Despite its simplicity, the system, Chris reckons, is one of only a small number of such systems in the world being used on an intensive poultry farm and probably the only one using this type of digester.

Transporting the manure from the sheds

The process begins in the seven 106-metre-long chicken sheds, each one holding about 50,000 caged hens.

The manure drops through the cage floor onto a computer-driven belt which moves in one direction while the eggs roll gently across the cage floor onto another belt moving in the opposite direction.

At the end of the shed the manure is scraped onto an external conveyor belt and transported 200 metres to a set of three effluent tanks.

“It’s all automatic”, says Geoff. “Before we had this external conveyor belt, we just had a little truck that took around two or three loads per shed. So the belt has halved our time to do the manure runs.”

The conveyor belt transporting manure from the sheds to the digester
The manure is transported 200 metres from the chicken sheds to a set of three effluent tanks where it is made into a slurry before being pumped into the digester.

Making the slurry

The manure is conveyed into the influent tank where it is mixed with water to make a slurry.

“With poultry manure, you need a fair bit of water to dilute the manure before it goes into the digester”, explains Chris, “whereas pig effluent is already in a slurry. They pump it straight into the digester and there’s not a lot of equipment needed. It’s the same with intensive dairies over in America. They wash their dairies out so they’ve already got the waste water in there. We have to put our manure in tanks and mix it first. So it is a more complex process to do what we’re doing here. And it is quite expensive.”

The proportion of water to manure is roughly half and half, says Chris, depending on the ammonia levels in the digester.

“If you’ve got 130 tonne of manure, you need about 130,000 litres of water. And 90% of the water going into our digester is waste water.”

About 180,000 litres of water and manure is mixed in the influent tank for 3–4 hours before being pumped across to the equalisation tank.

The equalisation tank is where the slurry is stored before it goes into the digester. Over 3–4 days, 50,000–70,000 litres of fluid a day is automatically pumped into the digester.

In the third tank, end-of-lay hens (‘spent hens’) and any dead hens are pre-digested for 8 weeks before also being pumped into the digester.

The three tanks are similar in design, with rotating stirrers. The hen tank is covered to capture the gas, and the equalisation tank is partially covered to keep it cool and to stop any odours from escaping.

Capturing the methane

Once the fluid enters the digester, it takes about 25 days for the bacteria to break it down, releasing methane, a natural gas. The methane is captured under the polyethylene digester cover.

“It’s a continuous process”, says Chris. “As you put fluid in, gas comes out.”

To speed up the process, four mixers rotate the fluid for 1.5 hours twice a day.

“We mix at night time, or just on dark and early in the morning, because that’s when the least amount of power is being used.”

One of the four digester mixers
To speed up the process of generating methane, four mixers rotate the fluid in the digester for 1.5 hours twice a day.

Seeding the digester

The process of getting the digester fully operational took about 6 months, from May to September 2014.

Unlike pig manure, poultry manure does not naturally contain the bacteria required to break down the manure, so they have to be added to the slurry. This one-off process is known as ‘seeding the digester’.

“We started with 10 million litres of raw water, so we had to pump a few hundred thousand litres of pig effluent into the digester”, explains Chris.

“It’s a very slow process then. Very slow. You add a little bit of chicken manure, you check your pH level. If your pH level drops too much, you wait for it to go back up again, then add a bit more manure. The bacteria double in numbers every day, so once you’ve got a million, you’ve got 2 million, and once you’ve got a billion, you’ve got 2 billion.

“You can easily kill off the bacteria so you’ve got to be very careful at the start. It’s a living organism; that’s basically what we’ve created. It’s like a newborn baby. You can’t feed it until it grows and matures.”

Seeding the digester in the middle of winter also slowed down the process.

“The digester needs heat to function better and quicker, and we were down to 12 degrees when it’s supposed to operate around 36 to 40 degrees. So as the air temperature heated up towards summer, the big black cover heated the digesting fluid, and it exponentially increased the production of bacteria.”

Six months down the track and Chris is able to feed the digester every day or every second day and the pH is fairly stable.

“It’s not mature—mature could be a 2-year-old digester. But it’s mature enough that we don’t have to be quite so concerned about whether we put a little bit extra in one day. It’s like a stomach—if you overfeed it, it gets sick; if you put the wrong stuff in it, it can get sick.”

“We were happy when we got gas”, says Geoff. “It was probably more a feeling of ‘phew, that risk is ticked off’.”

Removing sulphur and moisture from the gas

Before the methane can be used in the generator, it first has to be ‘scrubbed’ to remove the sulphur which could corrode the engine.

The methane is pumped from the digester to a sulphur scrubber and then to a condenser unit where it is chilled to remove any excess water from the gas.

The waste from the digester

Once the bacteria have done their job, the watery fluid that remains is gravity fed to a large purpose-built evaporation pond capable of evaporating up to 50,000 litres a day.

As its still early days, the exact proportion of solids coming out of the digester remains to be seen but Chris estimates it at 4% to 5% of the solids that go in.

Generating electricity from methane

With the digester maturing over the six months to September 2014, the generator first produced electricity in December and, according to Chris, is still “settling down”.

The methane from the condenser is pressure-fed into the engine, which drives an alternator or generator to produce power.

The brand of generator was not that important to Chris: “Our generator’s a Deutz but gas generators are pretty much a known commodity—you buy them, you know they work. For this project the critical thing has been the actual generation of gas from poultry manure.”

Chris uses a device called a ‘load bank’ to control how hard the generator is working. “The load bank allows us to manage the load that’s placed on the generator so it’s working most efficiently all the time.”

The generator
The methane is pumped from the digester and when sulphur and excess water have been removed, the methane is pressure-fed into the engine, which drives a generator to produce power.

Balancing the electricity load

The company’s goal is to satisfy its power demand with renewable energy as much as possible. This means managing the seasonal and daily peaks and troughs in power usage.

“In summer time, our electricity consumption in terms of kilowatts per day is two to two-and-a-half times what it is in the winter”, says Geoff.

There’s a combination of reasons for the fluctuation:

  • As the day gets hotter, more cooling pads and evaporative fans are turned on in the chicken sheds.
  • The grading floor and the cold rooms where the eggs are stored are all working harder in summer than in winter.
  • When the feed mill is turned on, electricity use spikes.

“The challenge for us is to reduce that peak behaviour. That will be part of the learning over the next 12 months as we grow to understand the unique behaviour of each piece of equipment.”

The size of the generator, which has a maximum capacity of 250 kilowatts, is also a limiting factor. “Anything over that, we’re importing from the grid.”

Staff check eggs for any defects
The grading floor is where the eggs are sorted by size, inspected for cracks, washed, stamped and packed into boxes.

The electricity generated from the methane cannot be stored but about a day’s worth of methane can be stored overnight under the digester cover.

The beauty of the new system, says Chris, is that he can graph everything by technology. “It’ll tell us how much energy the gas generator’s making, how much we’re using overall, and the differential, so we can change things to reduce the shortfall in summer.”

He is already planning to program the feed mill to start at 3am, when power usage is low, so that when he arrives at the farm at 6am the feed is ready to be put in the truck and delivered to the sheds.

Exporting electricity to the grid

While the company expects to have excess power available, especially in winter, exporting it to the grid is not currently seen as a viable option.

Chris explains: “We could export probably 50% in winter, but with the cost for us to hook on to the grid, and all the paperwork, and what they actually pay us for it, we would get only 10% or 15% of what we pay to generate the power. In other words, they’re not interested in the power, which is a shame because we do have a lot of excess in winter and at peak times in the mornings when they need it.”

Geoff likes to think that this will change as the bioenergy industry grows and matures.

“The regulatory requirements around exporting to the grid are far more complicated and expensive than for just using it on farm. And that will be an issue for the network infrastructure providers and the government as more of these initiatives are built”, he adds.

Reusing excess heat from the generator

The company rears its own hens from one-day old and LPG is currently used to keep the rearing sheds at the required temperature of 36 degrees for the chicks’ first 5–6 weeks.

Once the generator is fully online, the plan is to capture the excess heat it produces and use it to pre-heat the rearing sheds, topping it up using LPG.

The excess heat will also be used to heat water for washing the eggs.

“We’ll halve our gas usage as a result of using the excess heat generated”, says Geoff.

That’s just stage one, according to Chris. “There will still be excess heat so we’re looking at where else we can use it. That’ll be an evolution over the next few years, once we know how much extra heat we’ve got.”

Eggs being washed in the grading shed
The excess heat from the generator will be used to heat the chick-rearing sheds and heat water for washing the eggs.

Skills and expertise

What Geoff and Chris learnt from the US farmers they met was that the digester, once it is mature and operating reasonably automatically, needs only 1–2 hours attention a day to check oils, temperatures and pH levels.

“We’ve hired more people in the maintenance side of the business but that wasn’t necessarily because of the digester”, says Geoff. “Our business is highly automated so as we get bigger we just need more of that technical skill set to maintain and manage the equipment.

“It’s a very different type of expertise. When the maintenance crew were putting the gen-set in, there were two electricians, fitters, three laptops and some guy on Skype—not a spanner in sight.”

The power plant
“It’s a very different type of expertise. When the maintenance crew were putting the gen-set in, there were two electricians, fitters, three laptops and some guy on Skype—not a spanner in sight”, says Geoff.

Geoff sees Chris’s technical ability as the big advantage they’ve had. “He’s as good as the guys that did some of the installations. So we were able to balance the operational aspects of the business with what they require to actually give us the result. He’s been a big asset in managing and transitioning any continuity issues that we’ve had from the business while we’ve been building this.

“The benefit to the staff is that they’re very comfortable that we’re building a sustainable business that can continue to feed the growing population with an affordable protein source, and that they’ve got secure employment and they’re learning and being trained.”

The company employs about 22 people across the business.

Monitoring and maintenance

Once the generator is fully commissioned, Chris will be able to use his mobile phone to log in and see how much power they’re producing, and be able to start and stop processes in the same way he does today with the controls for the chicken sheds, the egg collection, the manure conveyor, the grading floor and the feed mill.

If there’s a water failure, a power failure, a feed failure, a rise in temperature or a drop in temperature, an alarm is triggered and a text message is sent to six people.

“Nearly every process of this farm is computerised and accessible by internet or mobile phone. It’s just how the world is now”, says Chris. “It’s very good for monitoring. We also have backup phone lines. Everything’s got to two or three redundancies when there’s bird welfare involved.”

The local electricians that the company contracted to install the equipment can also log in to the controllers via the internet and they get support from US-based RCM International.

Chris checks the digester controls.
“Nearly every process of this farm is computerised and accessible by internet or mobile phone. It’s just how the world is now”, says Chris.

Regulatory requirements

The company had to get a number of approvals to build and operate the power plant.

“We were aware that there were quite a lot of requirements, and that was part of the investigation”, says Geoff.

“What I wasn’t prepared for was the level of work required, not just in terms of the technical data but all of the other things that are needed to get those things across the line. Its substantial amounts of time to get the thing up before you dig a hole.”

  • The local council had to approve the DA for building the digester.
  • The Queensland Department of Agriculture, through the Environmental Protection Agency, had to issue an environmental certificate for poultry production, inclusive of the digester.

    To get the environmental certificate, Geoff says, required spending a lot of money on consultants for reports on odour, noise, dust, traffic.

    “We had to base model everything before the development construction. Then we had to do it post the development construction. And then we had to do it with and without the digester. That was quite a lot of work.”

  • The business is classified as a power plant, so they had also had to get petroleum gas approval from the Queensland Government.
  • Ergon Energy, the electricity network provider, had to sign off on the installation, and on the synchronisation between the grid and the plant.
  • Finally, the plant had to be approved by the renewable energy regulator.

Lessons learnt

The biggest risk of the entire project was the gas production and the company has now proved that high quality methane can be produced in large quantities from poultry manure.

“The whole project’s been a two-and-a-half-year journey to where we are today”, says Geoff. “In November 2013, the scrapers and dozers turned up on site and started digging holes in the ground. We’re one year on and we’re producing electricity.

“What you can do and how you do it is limited by your own imagination and the funds you can access. It’s been a lot of work collectively for the family to get to this point. Is it the right decision? Absolutely. No question of that. Has it tested our faith and challenged the decision that we’ve made? Absolutely.

“But the beauty of it is that we’re pioneering this for an industry. The industry can replicate this, and we’ve been very open and willing to share our learnings to the industry.”

Geoff’s advice to other poultry farmers embarking on a similar journey
  • Keep a good attitude and be patient, though this may be a challenge.
  • Explore all options and be open with everyone.
  • Don’t be afraid to ask for help or solicit other people’s views — it’s not an exact science.


Geoff Sondergeld,
Darling Downs Fresh Eggs,
24 Tummaville Road, Pittsworth, QLD 4356
Phone: 07 4693 5173
Email: geoff@fresheggs.com.au
Chris Adams,
Technical Manager,
Darling Downs Fresh Eggs,
24 Tummaville Road, Pittsworth, QLD 4356
Phone: 07 4693 5173