RoCa Power Station
Innovation of the process design is a key characteristic of the RoCa3 combined heat and power plant. Thanks to the combined production of heat and electricity this unit boasts a higher yield than with separate generation of electricity and heat. Situated on the border of Rotterdam and Capelle aan den IJssel the RoCa3 power station is also notable for the fact that part of the flue gases from the gas turbine are enriched with CO2 by after-burning. After cooling (while steam forms) a compressor is used to bring this part of the flue gases up to pressure so that they can be transported to the greenhouse region to the north of Rotterdam. The CO2 in these flue gases acts as a nutrient for greenhouse production. The heat from the power station is also transported to this same area where it is used for heating the greenhouses.
RoCa3 has an ingenious recycling system of natural gas, heat, electricity and CO2-enriched flue gases. This means a very high energy and environmental yield.
Generation
By supplying CO2-containing flue-gases to the greenhouse cultivation sector the power station’s annual CO2 emission is cut by 130,000 tons. This is comparable with total emissions by 40,000 cars each driving 25,000 kilometres. The combined generation of electricity and heat, plus supply of flue gases containing CO2 to the greenhouse cultivation area around Bleiswijk also saves the same volume of natural gas as used by a town like Zoetermeer (population 116.045).
Process
The RoCa3 power station, located on the border between Rotterdam and Capelle aan den IJssel, supplies electricity, heat and carbon dioxide (CO2). Higher concentrations of CO2 in the greenhouses boost the growth of plants and vegetables. Hence, the regional greenhouse horticultural sector benefits in full from this environmentally friendly example of technological advances. In the combined heat and power plant RoCa3 a STEG-installation (comprising a gas turbine, a waste-gas boiler and a steam turbine) generate electricity and heat. A part of the flue gases is enriched with CO2 by an after-burning system patented by Energy Engineering Services, comprising a separate steam boiler. After the natural gas has been burnt the exhaust fumes are channelled out of the gas turbine (540 degrees Celsius) to a boiler. Here they are heated into steam – which runs a steam turbine. An electricity generator is linked to the steam turbine. The remaining energy in the steam is re-used for heat generation. Once the flue gases have emitted their heat part of this is taken to the CO2-boiler. Additional natural gas is burnt in order to increase the concentrations of CO2 in the flue gases. The gases with CO2-content are then cooled and compressed and transported to the greenhouse cultivators via a pipeline. The heat from the additional natural gas is used to produce steam and – once again - electricity. This way nothing is lost or wasted. The supply and removal of hot and cooled water goes via two pipelines between RoCa3 and the clients. Each of the three pipelines is ten kilometres in length.
The environment
The fact that heat is produced at the same time as electricity (total energy principle) means less fuel consumption than with separate generation of electricity and heat. Alongside 20% energy savings this also reduces CO2-emmissions. RoCa3 provides 90% of annual demand for heat and CO2 from 140 greenhouse cultivators (who only need to turn on their own heating in emergency situations).