McCain Foods Ballarat Facility

Description

McCain Foods’ Ballarat manufacturing facility has started work on a massive 8.2-megawatt renewable system for its Ballarat facility that consists of a ground-mounted solar array, solar car park shading and a cogeneration anaerobic digester that turns food scraps into biogas to generate energy. Cogeneration, or combined heat and power (CHP), is valuable for food processing because it generates electricity and heat simultaneously, recovering a high amount of usable energy from the electrical and thermal (heat) energy. Combined, the solar and CHP systems will reduce the facility’s energy consumption by 39 per cent, with the CHP system also reducing the site’s reliance on natural gas by up to 16 per cent.

To maximise both the amount of energy recovered from the biogas and increase the opportunity to utilise the biogas through changes in gas production quality and quantity, McCain selected a modular Capstone Microturbine system for this project. The system being delivered is based on two (2) x Capstone C600S packages. Each package includes three (3) fully independent 200 kW Microturbines. At a combined 1,200 kW of power generation, the combined packages are sized to utilise the maximum biogas production available. Capstone Microturbines can tolerate a large variation in biogas composition, making them an ideal choice for the changes in gas quality that occur with anaerobic digestion. In addition, each turbine can turn down (i.e., part load) or turn off based on response to gas volumes or power demand. This system can produce between 100 kW and 1,200 kW. Each of the 6 x 200 kW modules can be serviced while the remaining units continue to operate, providing power continuity at all times.

For McCain, the solution was developed to maximise the total energy efficiency of the biogas. To achieve this, Optimal developed a heat recovery solution using Saacke’s range of cofired burner technology. Normally, a hot water or steam boiler takes ambient air into the burner, adding fuel to lift the air to the required temperature to generate steam or hot water. Saacke’s burner technology allows the burner to use both the turbine exhaust and fresh air as combustion air. Because the turbine exhaust is much hotter than ambient air (>280°C), the burner needs to add less fuel (natural gas in this case) to produce the same amount of steam. With 18% oxygen, the turbine exhaust can be used directly for combustion, or mixed with fresh air where not all turbines are operating.

In the case of Capstone Microturbines, there are no cooling or lubrication circuits, so almost all of the energy not converted to electricity is available as exhaust heat. Using the exhaust heat directly as combustion air harnesses 100% of the available thermal energy, which results in total system fuel efficiency above 90%.

The high-efficiency CHP installation reduces the CO2 emissions equal to the 7 MW of PV being developed, demonstrating the unique potential of biogas to reduce emissions for the food industry.