Heat recovery for better climate. Triple EEE at Peter Vosters

Peter Vosters uses heat from the air scrubber for lower gas costs. Because the incoming air is warmer, this is also beneficial to the climate.

Heat recovery provides better climate in the barns.

Peter Vosters’ pig farm is located on the outskirts of the Brabant village of Reusel. When he was developing plans for the expansion of his pig houses in 2009, it soon became clear that he would have to significantly reduce the ammonia and odour emissions. Vosters therefore opted for a combi air scrubber with a biofilter from Inno+. The system filters out 85% of the ammonia and 75% of the odour from his barns. All the farm buildings are connected to this system. The sow farmer likes the air scrubber, but he was bothered by the idea that this system would waste valuable energy. This was mainly because some 27,000 cubic metres of gas would be needed to heat all the sections on an annual basis. ‘After feed, natural gas was the biggest cost on my farm,’ says the businessman. Therefore, he began considering ways the energy from the air scrubber could be used to lower the gas bill. At the same time, he wanted to do something that would have a positive impact on the climate in the barn. Animal health is becoming increasingly important, and certainly for the weaned piglets it is a delicate matter indeed. Heat recovery turned out to be the golden egg.

Accurate measurements provide clear insight

Before Vosters started making major investments, he first wanted to know exactly what savings could be achieved. Since he kept accurate records of energy consumption, he already had comprehensive data for the last few years. Working with Inno+, he started measuring the gas consumption per barn. This involved the installation of separate gas meters in all the barns and sections with a gas connection, for both the sows and the weaned piglets. The energy consumption was logged for a year. ‘This gave us a picture of the scope of the energy consumption. It turned out that two-thirds of the gas was used for the young piglets and the rearing. That’s about 18,000 cubic metres per year.’

After looking at ways to reduce the gas costs, he arrived at the Triple EEE system. That’s a system for recovering heat from the barns. ‘It proved to be the most efficient way for me to use animal heat captured via the air scrubber for my farm.’

Preheating air with Triple EEE

With Triple EEE, the air scrubber has been expanded with a water/water heat exchanger. This heat exchanger extracts heat from the scrub water. The installation is located in the technical room, alongside the air scrubbers. By placing it as close to the scrubber as possible, little energy is lost. The heated water is then transported via an energy-efficient circulation pump through a closed circuit to the air inlet in the farrowing and rearing house. There, the heated water comes into contact with the incoming ventilation air via an air/water heat exchanger. The temperature of the water from the air scrubber is at least 17 °C. Using this heat, the incoming air can be preheated to 14 to 15 °C. Then incoming air is further heated to 19 °C in the air duct below the floor of the barn. The system works without a heat pump and without any modifications to the central heating system. ‘Therefore, a relatively low investment of around €40,000 is all that’s required.’

There are a number of benefits to preheating the incoming air to boost the temperature. For one thing, this makes it possible to maintain a somewhat higher minimum ventilation level. It also helps prevent draughts, because there is less difference in temperature between the incoming air and the barn air.

The system runs when the outdoor temperature drops below 15 °C. ‘In practice, that’s around 7,000 hours per year or about 80% of the year,’ says the pig farmer. His central heating system only runs on the cold days of the year. The design of the technical installation sounds simple. The tricky part, however, was getting all the individual components working together properly. That includes the climate equipment, the central heating system, and the circulation pump. For example, it is important that the central heating system does not kick in until the Triple EEE system has raised the temperature in the barn as close to the set temperature as possible. And too much heat in the barn would cause the ventilation system to run more than necessary, wasting a lot of energy.

Lower costs and improved growth thanks to heat recovery

The system has now been up and running for 26 months, to the pig farmer’s complete satisfaction. From the relaxed behaviour of the piglets in the barn you wouldn’t know it is a cold spring day outside; the climate in the various sections is perfectly comfortable. Vosters has calculated that heat recovery cuts his heating costs by around 60%. The pig farmer emphasizes, however, that it is not just about the money. ‘The temperature of the incoming air is now more constant and higher in the pig boxes. This allows me to ventilate optimally all year round for a healthier climate for the piglets and the breeding gilts.’ The exact result of the system is difficult to measure. The effects he does see are:

• More vital piglets and a higher growth rate. ‘It’s gone up by about 8%.’
• The piglets clearly suffer less coughing.
• The mortality percentage has decreased by 1.5 to 2%. ‘That can’t be a coincidence.’
• A 60% reduction of heating costs.

Heat recovery investment recouped in 6.5 years

The investment in the heat recovery installation at Peter Vosters’ farm amounts to approximately €40,000. Annualizing the costs (depreciation, interest and maintenance) at 15% equates to approximately €6,000 in costs per year. The pig farmer has calculated that, thanks to the installation, he can save about 60% on heating costs in the barns. This includes the energy costs for the circulation pump. Naturally, the energy savings will vary from year to year, based on factors such as how severe the winter is and the price of natural gas. Vosters expects an average savings on natural gas of approximately €6,300 per year. That equates to a payback period for the installation of about 6.5 years. He has not factored in the benefits of a better climate on animal health and results. It goes without saying that the costs and payback periods may differ between pig farms. The size of the investment depends, among other things, on the size of the farm and the design of the barns. For estimation purposes, Inno+ uses a metric of €15 to €25 per piglet place.

Read more here about the Triple EEE system and heat recovery in the Inno+ barns.