By Gordon Murray
While visiting the power plant owned by NV Elektriciteits Produktiemaatschappij Zuid-Nederland (EPZ) in Borssele, the Netherlands, I was reminded of the story of the little Dutch boy who saved his country by plugging a leaking dike with his finger.
By Gordon Murray
While visiting the power plant owned by NV Elektriciteits Produktiemaatschappij Zuid-Nederland (EPZ) in Borssele, the Netherlands, I was reminded of the story of the little Dutch boy who saved his country by plugging a leaking dike with his finger. He stayed there all night, in spite of the cold, until the adults of the village found him and made the necessary repairs to prevent the ocean from flooding the country. The Borssele power plant, on the Netherlands’ south coast just a few kilometres from Belgium, is protected from the Atlantic waters by a dike and could very well be the spot where the brave boy performed his heroic deed.
|The EPZ Borssele power facility comprises a nuclear reactor, a coal and biomass power generating station, and several wind turbines. Photo: EPZ
Borssele is EPZ’s only facility, but it exhibits a range of diversity in power production. It consists of the Netherlands’ only active nuclear power plant, a thermal power plant, and a wind park. Nuclear energy provides 485 MWe (MW electrical) capacity, thermal power provides 403 MWe capacity, and wind power 12 MWe capacity. The thermal power plant burns coal and biomass, operating at 40% efficiency. With approximately 450 employees, the combined facility generates about 8% of the Netherlands’ electricity.
Just a short distance from the EPZ Borssele facility is a large natural gas power plant. So, in the space of a few kilometres, electricity is being produced by a nuclear reactor, coal, biomass, wind, and natural gas. The generation mix in the Netherlands is 60% natural gas, 21% coal, 9% renewables, 4% nuclear, and 6% other. The renewables mix includes 48% wind, 39% biomass, 12% waste to energy, and 1% solar/hydro.
EPZ is a joint venture (50/50) between Delta N.V. and Energy Resources Holding B.V. It was formerly 50% owned by the Dutch utility Essent. In addition to its share of EPZ, Essent had a portfolio of gas and coal power plants. In 2009, Germany’s RWE acquired all shares of Essent. However, Delta, owner of the other 50% of the Borssele plant, said that the majority of its shareholders had demanded that EPZ should remain in public ownership. Delta took Essent, RWE, and Essent’s 136 public shareholders to court, claiming that they had acted unlawfully through the way in which the transaction structure of the deal had been specified. A court in Arnhem, the Netherlands, ruled in Delta’s favour in July 2009, saying that Essent’s shares in EPZ must remain in public hands. Essent’s stake in the Borssele plant is now owned by Energy Resources Holding B.V., whose shareholders are local and provincial governments in the Netherlands.
I was accompanied on my visit to EPZ’s facility by Mieke Vandewal, marketing manager of fuels at Peterson Control Union Group, a logistics, quality, certification, and risk-management company based in Rotterdam.
We were hosted by Jos Weststrate, manager of supply chain for the thermal power plant. Weststrate is responsible for coal and biomass fuel supplies, maintenance of environmental permits, ash and gypsum handling/distribution, and laboratory and field operations. Upon arrival, we were required to pass through extremely tight security and prohibited from taking photos, which is understandable, given the nuclear reactor.
The thermal power plant, established in 1988, consumes about 200,000 tonnes/year of biomass and 800,000 tonnes/year of coal. Weststrate says, “The plant consumes about 20% biomass by weight, which translates to about 16% by energy because biomass has slightly lower energy content than the hard coal we use here at Borssele.”
“EPZ began biomass co-firing in early 2000,” he says. “While the predominant biomass fuel is wood, we also use a tiny amount of cocoa meal. Since 2000, the plant has used about 30 different biomass suppliers. Presently, biomass is sourced from about 10 suppliers. All biomass is in pellet form.”
|EPZ replaces about 150,000 tonnes/year of coal at Borssele by co-firing 200,000 tonnes/year of biomass, mainly in the form of wood pellets. Photo: Gordon Murray
The Netherlands promotes biomass fuel consumption for power generation as a means of reducing CO2 emissions. The Dutch government’s support mechanism for large-scale co-firing provides a feed-in tariff of about six to seven cents euro per kilowatt-hour. However, there is some uncertainty because the scheme will run out by 2012 and it is uncertain if it will be renewed or replaced.
Coal and biomass for Borssele is sourced from many countries, including Canada. Typically, large Panamax and Capesize freighters will be unloaded in the deepwater Port of Rotterdam, stored temporarily, and then reloaded to Coaster-size vessels or barges and shipped to the Port of Vlissingen, which is too shallow to accommodate the large transoceanic freighters. After being unloaded, coal is stored outdoors, whereas pellets are stored under cover. After being gathered by reclaimers, coal is moved by conveyor to the power plant. Pellets, on the other hand, are loaded into trucks by front-end loaders and transported to the power plant.
EPZ uses a direct co-firing process to burn the pellets and coal. Once coal reaches the power plant, it is reduced to fine powder in coal pulverizers, which press the coal powder through sieves. Wood pellets are handled separately because wood powder tends to plug the sieves in the coal pulverizers. Instead, wood pellets are reduced to powder in hammermills. The coal powder and wood powder are each blown separately by hot air into a suspension-type boiler, where the powder instantly catches fire and burns with high intensity. The heat boils water, creating high-pressure steam to rotate turbines.
As the coal and biomass burn, they produce ash and emissions such as carbon dioxide, sulphur oxides (SOx), and nitrogen oxides (NOx). The gases, together with the lighter ash (fly ash), are vented from the boiler up the stack. Large air filters called electrostatic precipitators remove nearly all the fly ash before it is released into the atmosphere. Scrubbers and other pollution control equipment are used to reduce emissions into the air. The heavier ash (bottom ash) collects in the floor of the boilers and is removed.
Meanwhile, steam moves at high speed to the turbines, propelling the turbine blades and causing the turbines to spin rapidly. A metal shaft connects the turbine to a generator. As the turbine turns, it causes an electromagnet to turn inside coils of wire in the generator. The spinning magnet puts electrons in motion inside the wires, creating electricity. Transformers increase the voltage of the electricity generated, and transmission lines carry the electricity through the grid to substations throughout the
The spent steam exits the turbines and passes over cool tubes in the condenser. The condenser captures the used steam and converts it back to water. The cooled water is then pumped back to the boiler to repeat the heating process. At the same time, cold water is piped in to keep the condenser constantly cool. This cooling water, now warm from the heat exchange in the condenser, is released into the ocean.
EPZ replaces about 150,000 tonnes/year of coal at Borssele by co-firing 200,000 tonnes/year of biomass. At 2.86 tonnes of CO2 emitted per tonne of coal, biomass co-firing eliminates about 430,000 tonnes/year of fossil CO2 emissions, as well as reducing SOx, NOx, mercury, and other heavy metals. So like the boy who saved Holland from flooding, Weststrate and his colleagues at EPZ are doing their small part to help save the Earth from the effects of climate change.
|Supply Chain Supervisor
Mieke Vandewal is marketing manager of fuels at Peterson Control Union Group (PCU). PCU, headquartered in Rotterdam, the Netherlands, is a logistics, quality, certification, and risk-management company with 2000 employees in 50 countries. The company was established in 1920 as a privately owned inspection company for grain, which was traded and transported on the rivers and canals of the Netherlands. Over the years, PCU has expanded into many industries, including agriculture and feed, biofuels and biomass, coal, minerals, food, forestry, oil and gas, and textiles.
PCU plays an important role in the international wood pellet industry. The company provides independent verification for buyers and sellers by providing ship hold and cargo inspections, draft surveys to establish cargo volumes, and laboratory testing of product samples for certification and to ensure contractual standards are met. It also provides many other essential services, including remote temperature monitoring of storage silos for fire and explosion prevention, coordination of transhipping from terminals to power plants, and supervision of cargo unloading.
As marketing manager of fuels, Vandewal coordinates all activities from the time the ship is loaded in the exporting country through to unloading at the terminal, temporary storage, transhipping, and eventual consumption by the power plant.
Gordon Murray is executive director of the Wood Pellet Association of Canada (www.pellet.org).