In January 2015, WELTEC BIOPOWER started building an anaerobic digestion plant in Loughgall, Northern Ireland. The customer and operator of the 500-kW plant is the vegetable producer Gilfresh Produce. The enterprise produces numerous field-grown products and processes them into food. "For WELTEC, this is the third plant in Northern Ireland and thus the eleventh in the UK", says Kevin Monson, sales manager of WELTEC BIOPOWER UK Ltd., in Stoneleigh, Warwickshire.

Thanks to Northern Ireland's mild Gulf Stream climate, the products of Gilfresh grow well on an agricultural area of 1,000 ha. The product portfolio of the growth-oriented family enterprise includes root vegetables, salad crops and numerous cabbage varieties. The company - which was established more than 50 years ago and has almost 130 employees - also grows trend products like pak choi.

Gilfresh used to deliver the vegetable waste that accumulates in the sorting, washing and packaging processes to farmers as cattle feed. From July 2015, the waste and the vegetable washing water will be loaded into the bioreactor. To maintain an optimum stock level, an underground pre-storage tank is located before the two 2,625-m3 stainless-steel digesters; a 6,000-m3 tank is planned for gas-tight digestate storage. In addition to vegetable waste, cattle manure, chicken litter as well as whole crop, grass and maize silage will be used.

Especially in view of the different properties of the substances to be used, the investors were impressed by the WELTEC solution for uninterrupted entry of the input material: The robust MULTIMix system guarantees continuous utilisation and homogenisation of the substrates and stable plant operation.

In combination with an 80-m3 solid matter dosing feeder, the WELTEC system ensures optimum shredding and intensive mixing of the vegetable waste and long-fibre silage. The efficient pre-processing of the substances ensures, not only biological decomposition and efficient gas yield, but also low energy consumption of the plant.

"The biogas plant will enable us to pursue our growth course on the one hand and our ecological goals on the other hand", explains Thomas Gilpin, founder of Gilfresh. "WELTEC has designed the plant precisely for our specific production conditions. What ultimately conviced us was the fact that WELTEC was able to offer this flexible design with high-quality technologies at excellent conditions", says Thomas.

Another reason why he is pleased with the plant layout is that his company advocates the determined protection of resources.

In line with the goal to constantly improve the ecological footprint, the decision-makers decided to supply their own energy: About 40 percent of the power generated by the 500-kW CHP plant can be utilised in the company's own production process.

In the near future, the efficiency will increase even more due to the upcoming expansion of the cold storage. The excess power is fed into the public grid, and the process heat is made use of for heating the company buildings and for the production processes.

Such projects are necessary to enable the UK to provide 15 percent of their energy demand from renewable energy sources by 2020. Furthermore, carbon emissions are to be reduced by about three quarters by then, compared to 1990.

The UK have understood that besides wind and solar energy, another renewable source needs to be established in order to ensure reliable supply, and have subsidised bioenergy by means of measures such as attractive feed-in tariffs for regional power. "If other entrepreneurs follow the example of Gilfresh Produce, the United Kingdom will be able to reach the defined climate goals", says Kevin Monson.