CHP solution for Victorian Piggery

A second piggery location in northern Victoria is running the Inoplex combined heat and power generators.

This site demonstrates Inoplex¹s ability to provide a total embedded power and thermal turn-key solution. As well as supplying the generators for this piggery, our engineering team oversaw the build.

The site is up and running, fully approved by Energy Safe Victoria for Gas and Powercor for grid synchronisation and exporting, we¹ve successful had all aspects of the approvals granted.

Four by 50 KW generators are installed running on biogas from the anaerobic digestion of the animal excrement, the team laughingly call these our ‘Pig Poo Generators’. The biogas is treated, pressure boosted and treated through a biological scrubber to reduce the H2S, hydrogen sulphide, content as this is harmful to engines, exhausts, and the environment.

The power produced is used for the ventilation, animal feeding and care, lighting, and general requirements. While the engine and exhaust heat, thermal energy, are recovered and used for heating the piggery; making this a true combined heat and power project.

The power of up to 200 KW is connected to the site grid connection via a customised electrical enclosure with all of the required electrical protections included, and connection to the existing backup diesel generator. The site normally uses about two-thirds of the power generated, with the power exporting improving the projects return on investment with the extra income from power, renewable energy certificates and greenhouse gas carbon abatement.

A heat exchanger and pipework system transfers heat from the generator engines and exhaust into a hot water loop to heat the water that warms the piggery operations. A set of heat exchangers, one per engine, that collects the engine exhaust gas heat were designed and manufactured by Inoplex. We have found that this approach is cost effective and allows our team to custom size the equipment to fit in the space the client has available. Completing the regulatory approvals, the heat exchanger designs are registered as pressure vessels with the Victorian authorities so that we could provide the require Gas Type B approval for the system. 

When the summer months roll around the site’s thermal demand drops off to almost zero as the ambient temperatures exceed 40℃. The electrical demand then escalates with cooling and ventilation required for the pigs. An excess heat radiator system is located outside of the generator building in which heat from the engine and exhausts is eliminated to maintain the engines at an optimum temperature for longevity. Of course, this operation is simply managed via a PLC for a minimum of human intervention.

Project challenges

A complete project like this includes many hurdles that need to be overcome.

Power Factor

Like many established industrial and primary producers sites, this piggery uses a significant amount of reactive power. This reactive power is the electrical energy used for creating magnetic fields in motors and relays, etc. Here in Australia,  domestic homeowners to not have to pay for reactive power as a separate cost but commercial operations do, and this piggery had a significant cost for their reactive power. It was also a condition of their agreement with their local Power Authority that this power factor be managed to an agreed level when the generators are connected and paralleling with the grid. So, with these two compelling reasons, the Inoplex electrical team sized, built, and supplied a power factor correction solution for the site¹s preferred licensed electrical contractor to install. 

The solution included:

• Firstly, the equipment treats each of the three phases separately, so that as the site¹s electrical profile changes throughout the day, the Power Factor Correction equipment can adapt and provide clean power over a range of equipment running conditions. We have found this to be a difficulty with switched older capacitor-based systems and needed to do better for this client as the site electrical demand changed significantly.  We installed three separate power factor correction systems, one per phase all in the one neat cabinet to provide a dynamic and very capable solution.
• Secondly, the actual technology we used is an  ‘active power factor correction’ system,  a variant of an Active Harmonic Filters called a Static VAr Generator (SVG). These SVG devices produce results that the older capacitor based technology just cannot match and the pricing was modest. Additionally, for the sake of long term reliability, there is no issue with capacitor failures like the traditional capacitor banks and the SVG is not affected by harmonics or resonance. This new technology or approach causes the piggery owners and operators less to worry about breaking down. This active power factor correction has made power factor correction more attractive for more power users than the traditional capacitor banks. It also gives more kVAr per cubic metre than previously available and is by far the greatest return on investment available.

The Power Factor correction solution has since performed really well, we are very pleased with the result with the power factor consistently very close to the required 1. This power factor correction solution has virtually eliminated the site reactive power charges, providing a return on investment for the piggery of less than 2 years and allows them to run the generators paralleling with the grid and exporting when they have excess power.

Grid Protection

The power grid is maintained by the power authority with tight specifications for the customer as generators connecting to the grid can potentially impact the grid power quality. Also, in the event that the power grid is shut off for maintenance or an accident bringing down power lines etc, the power authority needs to be assured that the embedded power generators will not accidentally push power into the grid.

So while the Inoplex Inverter CHP’s include inherent grid protection, secondary protection is added to an installation to provide backup protection for the grid. For this site, the Inoplex electrical engineers provided a grid protection design that was approved by the power utility, and then designed the electrical enclosure with the required hardware and programming before a local power inspector approved the system and finally the power utility inspected and signed off again. 

This grid protection system protects the grid and personnel from:

• being supplied with power outside of the agreed specification (even when the grid power dips outside of this specification)
• the CHP generators exporting excess power and
• immediate disconnection if the grid is off.

The grid protection was signed off by all electrical contractors, inspectors, and power authorities and the site is running in parallel with the grid and exporting at its discretion.

Varying Biogas Quality

The anaerobic digestion of the pig excrement is a biological process and the calorific value of the biogas produced can vary during the seasons (as the covered anaerobic lagoon is not warmed) and with variation in feeds. Biogas from a piggery application is expected to have around 55% methane but we have experienced methane content of 42 to 70%,  so much broader than expected. Most engines run with the inherent assumption that the fuel quality is constant but our biogas engines are programmed to expect biogas quality to vary and the Inverter CHP Generators include an evolutionary optimisation, or ‘EVOP’, in which the air:fuel ratio is checked and tweaked automatically many times every day.

Advantages of using Inoplex

Our project engineering ability pushes us to improve our CHP Generators so that they are readily installed. For example, we provide the Gas Type B approval for each installation by including the Australian Gas Authority approved components, neatly incorporated into the CHP generator design. Next, we provide the documentation to Energy Safe Victoria though a licensed Gas Fitter who signs off the installation and arranges the Gas Inspector visit for approval on your behalf. Our project experiences and learnings are rolled into the generators to provide a more complete solution and making projects faster and providing a lower overall cost.

This project demonstrates the Inoplex broader capabilities with the CHP generators, electrical, gas and thermal engineering to take a project from concept to fully approved by the authorities and operational. Clean and renewable heat and power are produced for a more sustainable and economic production of pork. Whether you require just a generator for your project or a full Engineer, Procure and Construction, EPC, please contact us for the solution you require.