Biogas plant provides efficient power & heating

24th March 2015

Barney Scott

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In January 2015, WELTEC BIOPOWER started building an anaerobic digestion plant in Loughgall, Northern Ireland. The customer and operator of the 500kW plant is the vegetable producer Gilfresh Produce, which grows various products and processes them into food. The plant is set to reduce the amount of wastage incurred on the site, as well as generate energy to be used in production and to be fed back to the grid.

Thanks to Northern Ireland‘s mild Gulf Stream climate, the products of Gilfresh grow well on an agricultural area of 1,000ha. The product portfolio of the growth-oriented family enterprise includes root vegetables, salad crops, cabbages and 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 2,625m³ stainless-steel digesters; a 6,000m³ 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 80m³ 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.

In line with the goal to constantly improve the ecological footprint, the decision-makers decided to supply their own energy. About 40% of the power generated by the 500kW 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% 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 understands 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.

“For WELTEC, this is the third plant in Northern Ireland and thus the eleventh in the UK”, said Kevin Monson, Sales Manager, WELTEC BIOPOWER. “If other entrepreneurs follow the example of Gilfresh Produce, the United Kingdom will be able to reach the deﬁned climate goals”

“The biogas plant will enable us to pursue our growth course on the one hand and our ecological goals on the other hand”, added Thomas Gilpin, Founder, 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.”