The agreement has also provided a support package that has meant some biogas generators have clocked up more than 100,000 run hours and are still operating efficiently.
Southern tasked Finning with exploring how energy generation from biogas could be used alongside existing CHP equipment.
Biogas was already being used to power a sludge dryer, but Finning identified that installing a Cat G3520C gas generator to run off biogas would deliver an additional 1.95MWe – enough to meet all of the site’s energy needs. This is said to have allowed Southern Water to substantially reduce energy costs and its use of fossil fuels.
Caterpillar G-Series generators were selected for their ability to maintain a consistent output from varying gas quality. Furthermore, the system installed by Finning included both a gas collection and compression station to filter the biogas and remove some of the solids, as well as a gas clean up skid that removes other contaminants. This uses new technology to remove siloxanes, which if left would coat the engine cylinder head with a glass hard surface that would damage the cylinder heads and valves.
The success of this first project led to Finning installing seven more generators at other Southern sites. A modular approach was taken for all of these because installation of CHP equipment can mean significant disruption and downtime for plants.
Most of the necessary design and engineering work was completed at Finning’s own facilities, with the system then delivered in a series of self-contained modules in order to cut time needed on site by what is claimed to be as much as 50%.
For example, the modular packages at Southern’s Budd’s Farm facility included the generator set and associated synchronisation, G59 and LIMA remote control and monitoring equipment, a heat recovery system, as well as the gas collection and compression station, and gas clean up skid. For the Peacehaven site, the package was adapted to include a dual gas train allowing it to run on either biogas or natural gas. This was an important consideration as without power vital processes in the plant cannot operate. The package is therefore configured to run in island mode should the site suffer a mains power failure, enabling processes such as the supply of heat to the digesters, to remain at full capacity.
Additionally, Southern recognised that they would only receive the maximum benefits from the systems if they were kept running efficiently and reliably.
Matt Bryan, gas engines product support account manager for Finning said: “Crucially, as an investment for their business, Southern Water needed generators to perform consistently across a sustained period of time. Every time an engine was offline would not only cost them money in having to buy in replacement energy but also negatively impact their carbon footprint. So they needed specialist support in ensuring their generators were maintained to perform as reliably as possible.”
“This meant that specifying the right generators for their needs was only part of our challenge. In order for the project to be a sustained success we have devised and delivered a programme of maintenance and repair over the course of fifteen years. This has meant Southern Water benefits from high availability levels and minimal downtime.”
Finning based a team of gas safe registered engineers in the South of England to maintain them. These specialists are on hand to conduct routine and emergency work on all the generators.
This service is complemented by 24/7 remote monitoring of the generators.