As governments strive to reduce landfilling through directives and taxation, companies are starting to explore the possibility of using non-recyclable material to produce energy with the use of fluidized bed boilers.
One consequence of the European landfilling directive is the utilization of combustible recovered material in energy production. The EU target is that by 2016 the amount of biodegradable waste should be less than 35 per cent of the 1995 level. In order to encourage recycling and utilization, some countries have introduced rising levels of taxes and obligations with respect to landfilling. In fact, there is heated discussion about taxes in several parts of Europe. While the operation principle of the waste incineration is comparable to that of landfilling, companies must face the entirely new situation of having to find alternative ways to manage the waste generated in their operations.
Technology for recovery
The EU directives on reducing waste generation and increasing recycling support fluidized bed boilers, which enable co-firing. Using waste as the only fuel, boilers dedicated to incineration would demand increasing amounts of fuel, which would be highly contradictory to the objectives of the EU.
A ruling of the European Court of Justice has defined energy production based on incineration as disposal, while the utilization of recovered fuel in energy production is regarded as recovery. Emission trading in the EU area is based on this classification. Everybody involved, including those negatively affected, have adopted the view that boilers dedicated to incineration do not come under recovery. The recovery classification is awarded to co-firing boilers and cement kilns. Even CEWEP, which represents the incineration companies, subscribes to this viewpoint, although it is likely that they will try to change the decision into one that is more favourable for them.
Figure 1.The façade of the new biofuel power plant of Kappa Kraftliner, Sweden, which will also use small amounts of plastic reject
The emission trade aims at reducing the emissions of fossil energy production. Energy generated from the co-combustion of recovered fuel using fluidized bed technology is covered by this trade. It can be combusted efficiently and with minimized emissions using fluidized bed technology.
Recovering fuel and funds
Utilizing recovered fuel for energy generating purposes continues to be the subject of active study in Sweden, a country widely regarded as a forerunner in this field. Many companies are studying alternatives for utilizing recovered fuel as profitably as possible, offering technology suppliers interesting opportunities for cooperation. It is quite clear that more and more companies will be involved in the same area. For example sludge, which could earlier be taken to landfills or even spread in fields, is today an important source of energy.
According to Jouni Kinni, product sales manager of Kvaerner Power, there are several options for companies to take care of their waste management, but obviously those that offer an opportunity for a profitable business operation are considered most attractive. Large units may even consider setting up their own recovered fuel combustion plant. However, combustion of mere recovered fuel may also be fairly expensive since quite often the recovered fuel amounts from a single plant may be insufficient for feeding a combustion unit on a continuous basis.
Figure 2. The Kappa Kraftliner HYBEX boiler supplied by Kvaerner Power performs at steam: 132 MW, 50 kg/s, 120 bar, 520°C. It is fired by bark, sawdust, forest residue, peat, rejects, sludge and oil
Some companies, especially central European ones, have decided to start producing recovered fuel, i.e. crushing, removing metals and aluminium from the waste before using or selling it. This option may prove to become a profitable business, since there are companies that are willing to buy good quality recovered fuel for their own operations. For example, lime kilns can utilize it.
Discussion about recycling parks is also underway. A few recycling parks are currently either operating or under construction in Finland and more are planned. The idea is to maximize the recycling of material and the quality of the recovered fuel. The recycling parks handle both recycling and fuel preparation. There may be a power boiler as well, which enables the combustion of the recovered fuel and the recovery of methane generated in the biowaste handling for further utilization. Investing in advanced technology in the recycling parks is profitable due to high volumes. Companies that generate large amounts of waste often locate their premises around recycling parks. The experience has proved that fuel impurities, for example chlorine content, have reduced by 90 per cent as a result of separation at source and the technology of the recycling parks.
Many companies, including paper mills, may find co-firing to be the best option. It is especially suited for a mill that uses steam or other energy in its processes.
Kinni believes that with the biofuel-fired plant for Kappa Kraftliner AB’s mill in Piteå, in Northern Sweden, which will be Kvaerner Power’s first large BFB boiler delivery to the forest industry in Sweden, there is good reason to regard this project as “a multi-level environmental act.”
In his view this contract signifies a great market opening for Kvaerner Power. Kappa Kraftliner, the largest production unit of Kappa Packaging, the biggest kraftliner producer in Europe, brings a new and interesting aspect to Kvaerner Power’s reference history. Up to now the company has supplied similar boiler plants for utility purposes to municipal organisations in Sweden. While municipal organizations have alternative power generation options available for back up, the power boiler plant at Kappa Kraftliner will produce process steam together with electricity, which calls for the utmost availability in order to continuously secure the paper-making process.
Wide fuel range
Kappa Kraftliner’s current power boiler was originally a recovery boiler built in 1961, which was changed into oil firing in 1972. When the price of oil increased, wood reject from the mill’s own process was also used as fuel. The company is very progressive and development oriented. Their Tech Centre, built in the 1990s, focuses on product and production research and development. The aim is to increase production to 750 000 tonnes per year, and the biofuel boiler offers a new, technologically, economically and environmentally justified solution to satisfy the demand for heat and power.
With its new biofuel boiler, scheduled to start up in 2007, Kappa Kraftliner will be able to utilize biofuel sourced from outside the mill. Oil will be replaced by forest residue. Peat and sludge will also be used. The boiler will also use small amounts of plastic reject, which earlier has been transported elsewhere. No municipal waste is used. The mill’s own electricity production will increase, and process costs will decrease as a result of utilising biofuel. The biofuel combustion is CO2 free, which means that the company will gain benefits in the green electricity certificate rate. Also, the lower NOx emissions will mean that a lower rate of NOx tax is applied.
Figure 3. Fluidized bed technology is an effective means of co-combusting recovered fuel
“Even though the proportion of plastic reject in the fuel is small, the boiler plant is designed to fulfil the requirements of the EU incineration directive for co-firing, which regulates the combustion process and emissions,” Kinni emphasizes. “Also, the proportion of the plastic reject is so small that the energy generated at the plant can mainly be called green energy.”
In absolute figures, Kappa Kraftliner generates approximately 10 000 tonnes of plastic reject in a year. “Assuming the cost of reject at a waste incineration plant to be €100 ($121) per tonne, although this could be a lot higher in some countries, after adding transportation costs, the total cost per tonne would be many times this amount. This simple example gives an idea of the financial benefits of co-firing compared to waste incineration,” Kinni says.
Furthermore, the reject in Kappa Kraftliner’s case can be considered as good quality fuel with a high thermal value. A tonne of plastic reject generates approximately 3.5 MWh of energy, which equals a total of 35 000 MWh in a year. Generating the same amount of energy with another type of fuel would mean additional cost of €10 per MWh. This translates into total fuel savings of €350 000 yearly.
Figure 4. L. Ohlsson, president of Kvaerner Power (right) and T. Persson, managing director, Kappa Kraftliner AB at the contract signing for Kvaerner Power’s first large BFB boiler delivery to the Swedish paper industry
“The total savings amount to approximately €1.5 million each year. Compared to the additional investment and operating cost, the outcome would appear to be a profitable business. This is why it seems very likely that co-firing will be chosen at many paper mills and maybe other businesses as well,” Kinni concludes. When landfilling is no longer an option, new alternatives must be found, and profitable ones are obviously the most attractive.
Finnish technology leaders in bioenergy and fluidized bed boiler technology are well poised for promoting the utilization of recovered fuel. They have the technology for high-efficiency power production, controlling emissions and achieving the waste management standards. This is exactly what the international policy and objectives are seeking. This is an important reason for vigorous promotion and marketing, underpinned by the growing research and development component with the boiler manufacturer and research institutes.