Local Success Stories

Local Success Stories

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Sweden



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Production of district heating, district cooling,
electricity and biogas – Success Story Example 1

Introduction

Together with the owner the municipality of Borås, Borås Energi och Miljö AB has set up a goal to be free from fossil fuels. Borås is a municipally owned company that handles refuse and production of district heating, cooling and electricity in the municipality. 35.000 of the city’s 64.000 inhabitants rely on its district heating system, which receives it energy from a CHP plant using biomass, waste and landfill gas. The system also includes a scheme for district cooling. The city also uses biodegradable household waste in the production of biogas for transport (covering most of local bus transport) and production of fertilizer. This leads to considerable reductions in CO2 emissions.

System descriptions

District heating

BEM has several different district heating plants. The main unit, Ryaverket, is a combined heat and power plant. It has two biofuel boilers, two waste boilers and two generators. There is also an electrical heater plus two propane/biofuel/oil-fired boilers used as back-ups.












The biofuel boilers are grate-fired steam boilers. The biofuels mainly comprise forest fuel, i.e. fuel made from left-over materials from the forestry industry. Flue gases are cleaned by electrical filters connected to each boiler. Ash from the boilers is used as a forest fertilizer.

The waste incineration plant has two fluidized bed boilers using the latest technology. They burn the combustible portion of domestic waste (the white bags) and combustible waste from non-domestic sources. To ensure incineration is complete and to guarantee low emissions, the boilers are fitted with start-up and support burners. The waste boilers are connected to a flue gas cleaning system, in which slaked lime and activated charcoal are used to reduce pollutants. Particulates are then collected in a textile filter before the flue gas is passed to the chimney. Once metals are sorted from the bottom ash the ash is used as construction material at the BEM landfill. Fly ash is sent to Norway for treatment and permanent storage as a part of an environmental project.

Construction at Ryaverket began in 1965 and over the years the plant was modified several times towards more eco-friendly production. In the beginning, production was mainly based on fossil oil and a small percentage of waste. In 1984 the two large oil-fired boilers were converted to burn solid fuel (biofuel, 75%, and coal, 25%). A dryer was installed in 1994 to increase efficiency and allow boilers to be run on biofuel alone.

The first two waste incineration furnaces were opened in 1966, and a third was installed in 1972. The first two furnaces were shut down in 1987 for environmental reasons. The third boiler remained in operation until 1991 and was then closed.














In the beginning of the 21st century the City of Borås decided to build a new waste incineration plant at the same location as the old one. The plant, with its two fluidized bed boilers and modern flue gas cleaning technology, was opened in 2004.

To ensure a sufficient amount of energy in the district heating grid there are six smaller back-up and support plants located along the grid. The most frequently used is located at Ryaverket and consists of two boilers. Both boilers can run on propane but in 2007 one was converted to also run on bio oil. The remaining five plants, which run on fossil fuels, are only used in very cold weather or during scheduled and unscheduled maintenance at Ryaverket. The figure shows plant trends toward more eco-friendly generation.

There is also a heat pump used as a support plant; it extracts heat from sewage water at the local sewage treatment plant.

District heating grid

District heating is distributed via underground pipes to homes and other properties in Borås and is used partly to heat water circulating through radiators, and partly for heating tap water.

Construction of the Borås district heating grid began in 1959. Today there are around 300 km of district heating piping. There were 3,992 customers at the beginning of 2009, compared to 1,892 at the beginning of 2000. Approximately 35,000 inhabitants rely on district heating.

In addition to the large district heating grid in the centre of Borås there is also a smaller grid in the small community of Fristad (located about 15 km north of Borås). The district heating in this grid is supplied by its own hot water plant with four biofuel boilers and two oil-fired boilers used as back-up. Previously, the company had facilities similar to the Fristad plant in the communities of Sandared and Dalsjöfors. These areas were connected to the central grid in 2006 and 2008 respectively, and resulted in the more efficient generation of district heating and a reduction in emissions.

District cooling

In 1996 BEM built a district cooling grid to provide its customers an eco-friendly, economically-viable alternative to air conditioning. Today it produces up to 7 MW of district cooling via the central grid. District cooling is produced mainly at Ryaverket. There are two absorption chillers run by water from the district heating grid instead of electricity; only small amounts of electricity are needed for pumps and fans etc. Brine is used to transfer the heat between the different media. There are also three machines using conventional technology where cooling is produced by the use of electricity, and there is a small conventional cooling unit used as back-up on another site in the district cooling grid.

District cooling is produced in absorption chillers from surplus heat from the waste boilers. When no surplus is available, conventional technology is used. Two of the three conventional cooling units include heat recovery technology in order to exploit heat extracted from various buildings. This means that all the heat transferred from customers to the district cooling water is recovered in the district heating grid, including heat from the electric compressors in the conventional unit.

This variety of cooling plant options enables us to provide district cooling in the most economical and eco-friendly manner possible.

The district cooling grid supplies industries, offices, shopping centres and the local hospital with cooling to create comfortable indoor environments.

In addition to Ryaverket there are two other production sites in the city that provide cooling to two locations not connected to the central cooling grid. One of these is at the local hospital and consists of an absorption pump and two conventional units, the other is at an office centre and uses a conventional technology unit.

Electricity

Electricity is generated at Ryaverket and four different hydropower plants.

The two Ryaverket generators are driven by steam produced by the combustion of biofuel and waste. The generators were built in 1965, but were rebuilt and renovated in 2008 to obtain a higher electricity/heat ratio. In 2007, 134 GWh were generated at Ryaverket, and 44 GWh by the hydropower plants.

Electricity generated at Ryaverket and the four hydropower plants is sold to Nord Pool, the Nordic electricity market.

Energy services

In addition to the operations described above, BEM also provides a number of services to help with the reduction of energy consumption and the emission of greenhouse gases.

Energy Status

An energy status report is a summary of a property’s specific energy consumption, based on existing data. The aim is to assess the property’s potential for energy savings. The tool allows the owner of multiple properties to compare different buildings and apply measures where they will have the best effect.

Energy Analysis

In an energy analysis, a property’s energy consumption is plotted and proposals made for cost-effective measures aimed at energy savings and climate improvement. The analysis can be seen as a complement to the energy status service. If the client wishes, BEM can request and evaluate tenders for the measures proposed.The results can be used by the property owner whenever energy and climate-related decisions are taken with regard to the property.

Energy follow-up with KeepAnEye

The KeepAnEye tool ensures that the property owner always has up-to-date energy statistics concerning the property, and it allows the property owner to continuously monitor the costs and consumption of heating, cooling, electricity and water.

Climate Service

Through continual monitoring and maintenance a property owner can rectify faults, damage and leaks before acute problems arise. With Climate Service, BEM carries out checks and maintenance on that part of the district heating/cooling distribution system inside the property, i.e. the part for which the property owner bears responsibility for checks and maintenance.

Climate contract

Under a climate contract, BEM works together with the facility owner to optimize energy use in the facility. Work begins with an energy analysis to determine what can be done to optimize energy use in the property, and tenders for proposed measures are reviewed. If the client wishes to proceed, BEM takes on the role of project leader for the entire project.This allows facilities owners who otherwise lack the time or expertise necessary for the analysis to find the best solutions for optimizing their energy use.

Energy declaration

According to Swedish legislation (based on EU-legislation) an energy declaration must be prepared whenever a house is built, sold or rented out. The declaration must be prepared by a qualified energy expert, such as those at BEM. Since BEM already has knowledge of the properties we are able to help owners with their energy declarations in the most effective way.

Other climate saving activities

Collection of recyclables

BEM runs a large number of recycling stations and five recycling centres. Borås inhabitants can deposit recyclables i.e. packaging and paper, at the recycling stations, while various other types of waste such as hazardous substances, demolition waste, green waste from gardening and recyclables can be handed to recycling centres. The different types of waste are then transported to treatment facilities.

The provision of a place to dispose of their sorted waste gives Borås inhabitants an incentive to recycle e.g. plastics instead of discarding them together with non-recyclable waste. By enabling the recycling of such things as plastic bags and cardboard boxes, BEM contributes to a reduction in the need for raw materials and a corresponding reduction in energy consumption and emissions.

Collection of landfill gas

Gas has been collected from the landfill at the Sobacken plant since the spring of 2009. Were we not to make use of the gas it would seep away to atmosphere. The gas collected is used to fuel the process incinerator at the biogas plant, thus making more biogas (currently being burned) available for refining and use as vehicle fuel.

“Proof”

Energy use and CO2 emissions

The figures presented in this section are based on activities for the year 2006 as compiled by Profu in the report “Klimatpåverkan från Borås Stads energisystem” (Climate Impact, Borås City Energy System).

This section contains information about the conversion of energy from input to product and the emissions produced and saved from BEM’s main operations – the production of biogas and the generation of district heating, cooling and electricity. Benefits arising from the use of the BEM products biogas and district heating, cooling and electricity will be described in a later section.

The use of e.g. petrol in company cars is not included; neither is the production and transport of chemicals required for processes.

Energy usage in BEM operations

The figure below illustrates input and output energy streams at BEM. The figures describe conditions in 2006. The main energy sources were forest fuels and waste. The remaining fuel types were used as support fuels when outdoor temperatures were particularly low. In 2006 BEM used 948 GWh in processes that generated outputs equivalent to 731 GWh.

Emissions from the production of biogas and
district heating – contributions and savings

Emissions result from both the production of biogas and the generation of district heating, cooling and electricity. But overall, BEM operations lead to a net reduction in emissions. The figures are based on operations in 2006.

The use of fuels to generate district heating, cooling and electricity, leads to emissions. By making decisions based on awareness of the environment, the size and effects of those emissions can be reduced. The combustion of fossil fuels unavoidably leads to emissions of fossil CO2 and, depending on choice of fuel, N2O emissions. The choice of biofuel reduces direct emissions of fossil CO2 to zero, but with some remaining N2O emissions. By choosing locally-produced fuels that do not involve energy-consuming production processes, emissions resulting from production and transportation can be reduced.

As shown in the chart, the major proportion of emissions comes from the use of the fuel itself. The exceptions are electricity and forest fuel. Electricity does not produce emissions at the point of use, and forest fuel emissions are carbon neutral, although the transportation of forest fuel does often include the use of petrol or diesel.

The largest source of emissions is the combustion of refuse. Although refuse makes up almost 35 per cent of the energy input and emissions avoided by this operation, as can be seen below, this does not mean that refuse is a bad fuel. Refuse is presumed to contain a certain amount of fossil materials such as plastics.

In Sweden, the amount of trees being planted exceeds the number being harvested, therefore the use of forest fuel is not seen as a threat to the environment. The cleanest fuel with the lowest climate impact from greenhouse gas emissions is forest fuel. Forest fuel makes up more than 52 per cent of the energy input, but leads to emissions of greenhouse gases that are lower than those from fuel oil or LPG, which only make up 3 and 4 per cent of energy input respectively. In taking care of waste products and converting them into something useful, BEM has a positive effect on emissions.

By using biodegradable waste to produce biogas instead of dumping it in the landfill, BEM avoided emissions amounting to 10,000 tons of CO2 equivalents, and in using combustible waste as an energy source instead of dumping it in the landfill BEM avoided emissions amounting to 50,000 tons of CO2 equivalents. By producing electricity from non-fossil fuels, the need to produce electricity elsewhere by using fossil fuels is reduced, thus reducing emissions. As shown in figure 4, BEM had a net electricity production of 90 GWh in 2006, which contributed an emissions avoidance amounting to 15,000 tons of CO2 equivalents.

The chart shows the amount of emissions avoided by BEM operations. Secondary benefits such as the replacement of petrol with biogas, and individual heating with district heating, are not included

In summary, BEM operations for 2006 led to a net avoidance of approximately 1 kiloton of CO2 equivalents, excluding secondary benefits from the replacement of petrol with biogas and individual heating via district heating.

Benefits of district heating and cooling

General benefits

There are many benefits from district heating compared to individual heating, both for the environment and the consumer.

· By replacing a number of individual heating systems, e.g. oil or wood furnaces, all emissions are concentrated in one place for treatment by organizations with the necessary expertise and equipment, which results in more advanced, efficient flue gas cleaning and pollution control.

· Ryaverket is a combined heat and power generation plant, which makes it more energy efficient than individual heating systems due to simultaneous production of heat and electricity.

· This provides a stable heating/cooling system that requires less effort from the customer. The customer does not need to purchase and transport fuel.

The benefits from district cooling are largely the same as those from district heating. Moreover, district cooling solves the problem of environmentally harmful CFCs often found in air conditioning units.

Emission benefits

The figure shows the contributions and savings in emissions arising from the production and use of district heating and cooling in 2007. The information is an extract from the Profu report – “Klimatpåverkan från Borås Energi och Miljös fjärrvärmeproduktion”.

Local Success Story Varberg - Example 2

Five systems in a municipality

One major and four small district heating networks in a municipality with 56000 inhabitants supplies 7000 flats, more than 100 public and commercial buildings and almost 800 single family houses with district heating. More than 80% of the heat comes as industrial surplus heat and from biomass. The recycled heat and the biomass have to a great extent replaced natural gas, heating oil and electricity for heating. The benefits have been lower primary energy demand and lower CO2 emissions. Among future aims are to lower temperatures in network to facilitate use of lower temperature surplus heat.

System Description



Varberg Energy operates five district heating systems, one major and four minor in the municipality of Varberg, having about 56000 inhabitants. The major system supplies heat in the town of Varberg (27000 inhabitants), while the four minor systems are located in the villages of Tvååker (2400 inh.), Träslövsläge (2500 inh.), Veddige (2100 inh.), and Bua (1800 inh.). The major system had 93% of all district heat deliveries in 2008.

Customers served are 67 public buildings, 53 commercial and industrial buildings, about 7000 flats in 260 multi-family houses and 780 single family houses. During 2008, 467 TJ heat were delivered to the customers with total revenues of 79.5 million SEK. Hence, the annual average price of district heat became 170 SEK/GJ (17 €/GJ).

The market share for district heat in the town of Varberg is now about 45%. In 1999, the heat demands in Varberg were met by natural gas (39%), electricity (33%), heating oil (21%) and district heat (6%). A municipal decision was taken in 1999 to extend the supply of district heat in order to reduce consumer heating costs and for reducing the local emissions of carbon dioxide. Hence, Varberg started later with district heating than most other Swedish cities.

The major system are based on heat recycling of industrial waste heat from the Södra Cell pulp mill located in Värö, 18 km North of Varberg. One biomass steam boiler in Värö and one bio-oil boiler and five natural gas boilers fulfil the peak and reserve demands. During 2008, 469 TJ heat were supplied to the major system, thereof 375 TJ industrial waste heat, 58 TJ from biomass, and finally 77 TJ from natural gas. The industrial waste heat is the remaining process water from the pulp bleachery, originally mainly heated by internal biomass streams with a very small share from heating oil. The own use of natural gas was higher than expected during 2008, since the pulp mill used a longer period for maintenance than planned, giving less industrial waste heat. The four minor systems are supplied by heat from local biomass boilers with a total heat generation of 45 TJ.

The transmission pipeline from the pulp mill was constructed in 2001, see Picture 2.The first heat was delivering from Värö to Varberg on December 12, 2001. The Swedish government decided in March 2000 to support the transmission project with a 24 million SEK grant from the Swedish climate investment program (LIP). The main purpose with the grant was to reduce the financial project risk in order to receive the carbon dioxide emission reduction associated to the project.

The total trench length in the distribution networks is 113 km, thereof 106 km in the major system. The transmission line with double 350 mm pipes from the Väro pulp mill to the town of Varberg is 18 km long. Only prefabricated district heat pipes are used. The twin pipe solution is used for small dimensions. The total distribution heat losses constitute of 47 TJ, corresponding to 9% of the heat supplied to the systems. The indus5 trial waste heat has only a temperature of 80ºC. In order to maximise the utilisation of the waste heat, the distribution temperatures are kept as low as possible. During 2008, average supply temperature was 82ºC, while the average return temperature was 43ºC.

During the period of 2001-2008, 302 million SEK (30 M€) have been invested in the district heating systems. The total investments by year and purpose are presented in Table 1. The total cost for the transmission line from the pulp mill became 106 million SEK (10,6 M€), after deduction of government grant for the transmission pipeline.

System benefits

The major benefit with the Varberg district heating systems is that the heat recycling from the pulp mill and the biomass used have substituted the use of natural gas, heating oil and electricity for heating buildings in Varberg. Since 2001, the local use of natural gas has decreased with 75%. This transition from natural gas to district heat is illustrated in Figure 2. This quick transition became possible, since Varberg Energy also is the local provider of natural gas in Varberg.

The consequences from this fuel substitution are primarily lower primary energy demand and lower local carbon dioxide emissions. Since Sweden lacks fossil fuel resources, the substitution also lower the energy import, supporting a higher security of energy supply.

The figure shows the development of natural gas and district heat sales in the municipality of Varberg 1995- 2008.

The lower primary energy demand comes from the recycling of the industrial waste heat. Since the pulp mill mainly use biomass and recycled process resources, the heat recycling increase the overall efficiency of the biomass input to the pulp mill.

The lower carbon dioxide emissions come both from the heat recycling and the use of biomass. The fuel substitution is in compliance with national Swedish climate strategy, supported by a high carbon dioxide tax for domestic use of fossil fuels. During 2008, the tax was 1008 SEK/ton (100 €/ton), giving very high heating costs when natural gas or heating oil are used.

In 1998, the annual carbon dioxide emissions from fossil fuels were more than 90000 ton coming from heat supply to industrial buildings and buildings in the municipality of Varberg. The current annual reduction of carbon dioxide emissions from substituted fuels have been estimated to 36000 ton. The fossil carbon dioxide emission from the existing district heating system has been estimated to 4500 ton/year, giving a total reduction with 31500 ton or 88%. The reduction of nitrogen oxide emissions has been 20 ton/year.

In Europe and North America, buildings use mostly natural gas and heating oil directly in boilers for heating. This use gives specific carbon dioxide emissions between 70 and 95 g per MJ heat. The corresponding figure for the whole Varberg district heating system is only 10 g/MJ.

The total population in the town of Varberg and the four villages is about 36000. Hence, the current specific reduction amounts to 0.9 ton carbon dioxide per year and capita. The average specific carbon dioxide emission in Sweden is 6 ton per year and capita. Hereby, the district heating system in Varberg has also succeeded to lower the community carbon dioxide emissions with about 15 %.

Another benefit has been that the use of district heat will reduce the fire risk from local use of natural gas and heating oil.

The average heat use in multi-family buildings were 480 MJ/m2 during 2007 in the Halland county according to Statistics Sweden. Since the Varberg district heating system has only 27% primary energy share in the supply, the specific primary energy supply is only 130 MJ/m2. This is significantly lower than other heat demands in Europe.

During the transmission project, one new and innovative technological solution was used. A special pressure exchanger (invented by Bror-Arne Gustavsson) was installed for reducing the risk of water hammer in the transmission pipeline.

The developing strategies for the future are

· With respect to heat deliveries, our goal is to increase to 540 TJ in 2015

· An agreement has been met with the pulp mill to install a 10 MW flue gas cooler in the pulp mill chimneys in order to get some medium temperature waste heat as complement to the current low temperature waste heat. The new waste heat temperature will extend from 80°C to more than 90°C from November 2009.

· With respect to the total heat supply, our goal is to increase the industrial waste heat from 375 TJ to 550 TJ (90% of the total supply). The current amount of natural gas to the district heating system is around 10%. Our goal is to change our heat generation using biomass, biogas and bio-oil peak energy instead of natural gas. The goal is to fulfil this before the end of 2015

· Further lower return temperature in the major distribution network in order to increase the utilisation of low temperature waste heat from the pulp mill and to lower the distribution heat losses. Our 8 goal to the end of 2010 is to decrease the return temperature to below 40°C.in order to increase the supply of industrial waste heat energy

· With respect to carbon dioxide emissions, our goal is to increase the reduction to 45 000 tons until 2015. This corresponds to a 50% reduction compared to the 1998 level.

Conclusion

Varberg Energy has succeeded to reduce the local carbon dioxide emission with almost 90% for the district heating customers connected during less than 10 years. This reduction has been accomplished by using district heating system technology to recycle heat from a large pulp mill and by using biomass as fuel in heat generating boilers. However, we do not intend to end with our results. We are walking on a path containing further improvement.