Type of CHP system: Anaerobic digestion

Plant owner: SBI Friesland vof

Commissioned: 2002

Status of plant: Commercial

Contractor details:

Pretreatment/separation plant by Grontmij

Digestion plant by HCG (now GTI Fabricom)

Power generation: Gas engine

The gas is collected with the landfill gas and used in the engines for CHP production

Main fuel:

Biogas

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 5 MW

Total thermal input, incl. fossil fuels: 5 MW

Gross electrical output: 3,6 MWe

Net electrical output: 2,4 MWe

Heat output: 4,4 MJ/s

Electrical efficiency, gross: 36 %

Electrical efficiency, net: 36 %

Overall efficiency, gross: 86 %

Capacity figures are total of this landfill location + one digestion plant. Both plants are the same order of magnitude regarding energy production.

How is plant controlled: By the amount of waste

Heat backup: Natural gas for hot water

Heat usage: Heating only

Energy usage:

Heating of buildings, influent of waste water treatment plant and feedstock of the anaerobic digestion plant.

Capacity of the heating network is 2.2 MW, with

1.1 MW for the digestor,

350 kW for the waste water treatment plant and

750 kW for the buildings

District heat coverage (% of total demand in DH network):100 %

DH inlet temperature:110 °C

DH return temperature:90°C

Fuel storage:

At the moment there is no buffer, but is is planned to install a 50 m3 tank in short-term to compensate for the fluctuations

Waste water:

Expected to be 80,000 m3 per year. This water will be treated in a membrane-bioreactor and disposed on the public sewage system

Plant description:

The plant consist of three main components:

  1. separation plant for mechnical, dry separation of MSW and industrial waste,
  2. washing plant for the fine fraction (5.5 cm) called ONF, organic wet fraction,
  3. anaerobic digestion plant for the ONF fraction

Emission regulation is the NER

Fuel feeding system:

Before each reactor, there is a mixing/separator device where the feedstock is pumped and heated. Next, the reactors are fed batchwise

Feedstock:

Max. 20 t/hr ONF which is heated to 60 oC

Digester capacity: 3 times 3000 m3

Residence time: 18-20 days

Process temperature: Thermophyl, 60 oC

Annual gas production: 8.000.000 Nm3/year

Specific gas yield: about 100 Nm3 / ton ONF

Gas quality: Typical composition of the biogas:

62% Methane,

37% Carbondioxide,

1% Nitrogen,

0.1% Oxygen,

Sulphur compounds about 250 ppm after treatment

Engine:

Two 1.1 MW Caterpillars (36% electric efficiency + 50% heat efficiency) and

Four Waukesha engines from 300 to 475 kW (33% electric efficiency + 36% heat efficiency)

Caterpillars have flue gas heat recovery system

Flue gas cleaning: No

Heating value is 22 MJ/Nm3

Staff: The plant is serviced from Monday till Friday in 3-shifts

Electricity sale info: Peak/low load periods

Total capital cost: 15.000.000 Euro

Washing + digestion plant: 15 million

Data collected and quality assured by: Biomass Technology Group BV.

Contact person: Harrie Knoef