Use of Residual and Organic Waste
Industrial and agricultural residual waste flows are very suitable for generating electricity. The Nuon power station in Velsen has for years been using process gases of the steel manufacturer Corus, while our power stations in Lelystad and Buggenum burn or gasify organic waste as fuel.
Corus process gases
The IJmond 1, Velsen 24 and 25 power stations generate electricity with process gases that come from steel manufacturer Corus. These process gases, which are of no further use to Corus, are transported through pipelines from the steel plant in IJmuiden to Nuon’s nearby power stations. The gases are CO2-rich low-calorie furnace gases and medium-calorie coke oven gases which are released during the production of steel. Despite the low combustion value – that of furnace gas is only 10% of that of natural gas – these process gases are still useful for generating electricity.
About one third of Corus’s process gases currently go to Nuon, while the company uses the remainder for its own steam production and energy supply. Corus is seeking to further optimise its production processes, which will result in a higher steel output and – hence – more process gases. These gases may be made available to Nuon. We are meanwhile in the advanced stages of finding a suitable processing method involving a new gas turbine unit at the location in Velsen-Noord. Maximising the use of residual gas is important from an energy efficiency perspective. If the gases are not used by Nuon, Corus must flare them, resulting in the loss of the energetic value for a useful application. In this case Nuon would have to purchase energy in the form of coal, natural gas or power from elsewhere. In the current situation, Nuon ensures optimal and clean combustion with energy gains and CO2 savings. Combustible process products are thus put to good use.
Organic waste
The biomass power station in Lelystad is another location where residual waste flows are used. Every year some 25 thousand tons of clean wood cuttings are burned there, providing about 3,000 households with heating and power. This wood comes from the woodland estates of the Forestry Commission in the immediate vicinity. Apart from wood cuttings, no other biofuels are burned at Lelystad.
The Willem-Alexander power station in Buggenum uses various types of biomass and secondary fuels. This coal gasification power station currently co-burns numerous residual waste flows from the agricultural sector, such as sawdust, grape and sunflower seeds, and peanut shells. In the past a great many residual waste products were tested for their suitability for co-burning. The technical requirements for agricultural residual waste are high, particularly because the materials must not damage the installations. The sawdust that is used, for instance, is basically finely ground wood dust in order to obtain optimal gasification results.
Residual waste flows such as chicken manure, animal flour and palm oil are not used by Nuon. We look carefully at the origin of the biomass that we use in order to avoid unwanted practices, such as the felling of woods specifically for use as biomass. We also try to minimise the CO2 emissions during transportation, which is why ships are the preferred mode of transport. A special unloading installation with a silo has been built in Buggenum. The bulk of the residual waste products come from our neighbouring countries. The biomass that is used must comply insofar as possible with the government’s sustainability criteria formulated in 2006. This means that the CO2 balance must be in order and the production must not affect the worldwide production of food and animal feed or have any negative impact on the local biodiversity and economy. The government, knowledge institutes and the business community are seeking to set up a certification system for the importation of renewable biomass. This stems from the Accord of Schokland that was concluded last year and to which Nuon is a signatory. We expect that it will take a number of years to develop good indicators for verifying the sustainability of biomass.
