Staying Ahead of the Game

Owing to visionary environmental and energy policies combined with coherent public planning, Denmark has developed the most efficient waste management system in Europe. But with over 30% of capacity now more than 20 years old, up to ten projects are expected over the next few years. Bettina Kamuk looks at the progress. In 1997 Denmark became the first country in Europe to introduce a ban on the landfilling of waste suitable for incineration. This has proven to be a major benefit to the Danish economy and the environment. The waste management model in the country is based around municipalities - they have the responsibility and decision-making authority for the collection and treatment of household waste, and control the flow of commercial and industrial waste to assigned treatment and disposal facilities. Achitectural gems - leading international architects have been involved in designing many facilities. For example, Dutch Architect Erick van Egeraat won the contract to design the new inceneration line at Roskilde facility, pictured below Only inert waste is sent to landfill and following reuse and recycling, residual waste is incinerated. Danish WtE facilities treat approx. 3.6 million tonnes of waste per year, corresponding to approx. 26% of the total waste generation. By this the WtE facilities produce environmentally friendly electricity and district heating corresponding to the energy consumption of approx. 450,000 Danish households. Out of the total waste generation more than 66% is being recycled and less than 5% is being landfilled. Data from Eurostat also shows that the European countries which have an integrated WtE system have the highest recycling percentages. Integrated energy planning The first WtE facility in Denmark was built in 1903 generating electricity and heat for a nearby hospital. However, the major break-through happened in the 1970s during the first oil crisis. Danish policy focused on reducing dependency on oil, and large district heating transmission networks were established to ensure the greatest possible exploitation of the surplus heat generated at the local power stations. The incineration plants also benefited from this new energy policy as it became easier to sell district heating. When taxes were put on oil and coal for heat supply the WtE plants increased their sales of untaxed heat. Today the green house gas effect and climate change has focused the discussion even more and has encouraged politicians to recover an even larger amount of energy through WtE. Great efforts are being made in Denmark to enlarge the district heating network, and to change from fossil fuels to renewable energy like WtE. One of the world’s largest district heating networks is the Copenhagen network, stretching more than 50km from east to west. Three WtE facilities supply heat to the same network and more than 30% of the total district heating in the Greater Copenhagen area is generated by waste. In addition a district cooling system has recently been set up in the centre of Copenhagen, as well as at other WtE facilities to supply cooling to nearby shopping centres, hospitals or other buildings with a high cooling demand. Inter-municipal co-operation Most of the Danish municipalities are too small to handle the waste treatment tasks that have been imposed on them in an economically viable manner. As a natural consequence, most Danish waste treatment facilities are owned and operated by joint ventures between two or more municipalities. These public companies are led by a board consisting of municipal council members from the relevant municipalities. In this way local anchoring and ownership is ensured. In addition to incinerating waste, most of the companies also carry out other waste management tasks. Some of them for example, operate civic amenity centres on behalf of their municipalities. Costs that cannot be covered by the sale of heat and electricity must be covered by a gate fee, charged on the basis of the registered waste amounts. However, the companies are non-profit organizations and the gate fee is fixed in such a way that it only covers the costs that cannot be recovered by the earnings generated from the sale of energy. Together with the local district heating companies, the companies and the municipalities have secured the basis for recovery and extensive utilization of the energy produced from the waste. At present around 5.3 million Danish inhabitants share 29 WtE facilities, of which 24 are combined heat and power plants. Of these, 10 are supplying heat generated at older lines, and five smaller plants are generating heat only. Recently three smaller facilities owned by the electricity companies were mothballed as they were not economically or technically competitive. Modernisation of the Danish WtE capacity Over 30% of the Danish WtE capacity is more than 20 years old, and several WtE companies are at present planning new capacity for replacement of existing lines. Seven to ten projects are expected within the next few years. The new line at the TAS plant in Kolding, Denmark is equipped with advanced new combustion technology developed for fuels with high heating values Through the modernisation of the WtE capacity, old lines will be replaced with modern new plants that possess higher electrical efficiency, and greater heat production. By introducing flue gas condensation an even larger part of the generated energy can be recovered contributing to an even more efficient WtE sector in Denmark. Designing a WtE facility in Denmark As with all other energy generation facilities, WtE plants are designed in accordance with the specific properties of the fuel. Waste is far more complex than conventional fuels. Thus, when designing the plant it is of utmost importance to make sure the technology can withstand the environment, and can prove a high availability (>8,000 operating hours per year). All WtE facilities in Denmark use grate fired technology as it is able to treat the waste with a minimum of pre-treatment, contrary to emerging technologies which normally need pre-sorting and shredding. At the same time grate fired technology has shown a high energy efficiency with a minimum of own energy consumption, and last but not least it has proven the highest availability. At the Nordforbrænding plant in Hørsholm, Denmark insulated pipes deliver the hot water to homes within 30km radius of the incinerator The flue gas generated is cleaned of dust, heavy metals, acid gasses (HCl, HF and SO2), nitrogen oxides (NOx) and dioxins. The emission limit values are stipulated in the environmental permit of the facilities, which in turn is based on the Waste Incineration Order issued by the Ministry of the Environment and the underlying EU Waste Incineration directive (No. 2000/76). An environmental permit is required to operate an incineration facility. A permit can only be granted if emissions have been limited by applying the ‘Best Available Technique’. This term is defined in the EU Directive on Integrated Pollution Prevention and Control, and is expected to be replaced by a new Directive later this year, with implementation in 2012. Most of the Danish facilities operate far below the present emission levels and do not expect problems with the implementation of new emission levels. Architectural gems Steam boilers for waste incineration plants are up to 40 metres or more tall. Consequently, a modern WtE plant requires the construction of large buildings. Most of the Danish facilities have chosen to enclose the complete equipment contrary to other countries where part of the equipment - often the air pollution equipment - is placed outside the building. Fortunately, the Danish municipalities have decided to make these energy plants a landmark in the city. CO2-friendly energy resource Having a net calorific value of around 3 MWh/t, waste is indeed a useful fuel, however, because it contains mixed material, it produces a corrosive flue gas. Consequently, WtE plants are normally designed for a moderate electrical efficiency, and as a rule of thumb it can be expected that one tonne of waste may produce approximately 2 MWh heat and 2 to 3 MWh electricity. Various circumstances and local conditions may make it advantageous to optimise either the electrical or the heat generation. By generating electricity at the same time as combusting waste, considerable CO2 emission reductions can be achieved. The combustion of one tonne of waste can generate approximately 10 GJ electrical and heat energy. Should the same amount of energy be generated by means of coal, oil or natural gas, and the one tonne of waste treated by landfilling or composting a significantly higher amount of CO2. At the same time waste is a locally sourced fuel that in addition to reducing the use of fossil fuels, contributes to increasing fuel independence in Denmark. Economic aspects The Danish WtE facilities are subject to a cost coverage principle, which means that they can show neither a profit nor a loss. Receipts and expenses must balance within a small time span. Typically, the costs of incineration amount to approx. €100/tonne (exclusive taxes), while the earning from sale of heat and electricity amount to €70/tonne of waste, corresponding to a gate fee of €30/tonne. The gate fee in Denmark is one of the lowest in Europe and is due to the efficiently operated facilities on the one hand, and extensive energy recovery on the other. For the individual household, waste treatment by incineration typically costs the same as the household’s waste collection bag, i.e. less than €0.33 a week. The greater proportion of the waste management costs is therefore to finance the cost of collection, schemes for bulky waste, recycling and hazardous waste as well as taxes and VAT. Furthermore, studies have shown that heat from waste to energy facilities is generally the cheapest source of heating in Denmark. Bettina Kamuk is a member of ISWA’s Working Group on Energy Recovery and is market director of Ramboll’s WtE department.e-mail: bkc@ramboll.com More Waste Management World Articles Waste Management World Issue Archives