April 2018 progress report

Within the anaerobic digestion area, the main focus of the past few months has been on testing various parts of the equipment and processes. This has included the combined heat and power (CHP) engine, which has been run on imported biogas in a successful test. The CHP engine will be used to convert the biogas produced in the anaerobic digestion (AD) process into heat and electricity to be used on site, with excess electricity going into the National Grid.

The AD digester tanks have been inspected and pipes have been pressure-tested. Work is progressing on the site and we expect to start hot commissioning with food waste soon.

Within the gasification area, work is ongoing to enclose the building and complete the 15,800m2 of roof cladding covering the roof and sides – that's roughly equivalent to the size of two football pitches. Internally, the scaffolding has started to come down, over 70 miles of cables have been installed and radiography testing has been completed on all the welded joints, to ensure they are robust. The final structure on site, the ash handling building, is also nearing completion. This will house bottom ash produced by the gasification process, before it's transported off site.

The next step to prepare the gasification facility ready for commissioning is steam blowing. The purpose of steam blowing is to clean out the pipes to remove any construction debris or scaling from the inner surfaces of the pipework between the boiler and the turbine. This is necessary to prevent any debris getting into the turbine, which could cause problems with the turbine blades and general operation of the turbine.

Steam blowing involves pushing steam produced by the boiler through the pipes and then out through temporary pipework, so it doesn't go into the steam turbine. Before the steam is released, it goes through a silencer to reduce the noise and collects any debris. During the steam blowing process, you may see plumes of steam coming from the area, and this is perfectly normal.

Across the rest of the site, the most noticeable change has been the site entrance, which is now the final layout and substantially complete. Work has also started on the weighbridge to the east of the AD facility. This new weighbridge is the third on site and will weigh trucks within the site, when they are tipping in more than one location, so we have an accurate record of how much waste of different types has been tipped. The other two weighbridges, which have already been built, weigh the trucks as they enter and exit the site.