BioCycle April 2011, Vol. 52, No. 4, p. 32
A range of tools, including anaerobic digestion with upgrading of biogas for vehicle fuel and district heating using woody biomass, enable this city in southern Sweden to significantly reduce fossil fuel use.
IN 1999, the executive committee of Kristianstad municipality in Sweden unanimously declared its will to make this city of about 80,000 people become Fossil Fuel Free. In addition to wanting to reduce reliance on imported oil, a major impetus was to be very proactive in combating the effects of climate change, especially severe flooding and rising sea levels. “The town of Kristianstad is located in a low-lying area on the banks of the River Helge, close to the Baltic Sea, so we wanted to take steps to significantly reduce our carbon emissions,” says Lennart Erfors, city engineer and climate strategist.
Reduction of fossil fuels was to be achieved primarily by use of biofuels – both biomass for heating and electricity production, and biogas as fuel for local buses and other vehicles, and to supplement the district heating. By 2008, Kristianstad was achieving annual CO2 emissions reductions of 123,000 metric tons, about one-quarter less than 10 years earlier. Its use of fossil fuels has been cut in half.
“Kristianstad began building its district heating system in 1980, following the first global oil crisis,” says Erfors. “Later, it was discussions on how to manage waste that led us to look at using the organic fraction to produce biogas.” He recalls that a debate on waste incineration in the mid-1980s sparked the conversation about using woody biomass to generate electricity and heat. “A decision was made to not choose waste incineration, but instead generate combined heat and power (CHP) using wood fuel,” he adds.
Kristianstad is the capital of the Region Skåne, which has many smaller towns and villages outside of the city center. The region has some of the best agricultural land in Europe. “Good farming conditions, a high level of mechanization, a good environment and specialized investment in research and development have made Kristianstad into one of the major food centers in Sweden,” according to a case study on the city prepared for the European Commission’s Directorate-General for Energy and Transport. “The extensive food industry results in large amounts of organic waste, which along with large amounts of manure gives the material for biogas production.” The most famous product from Kristianstad is Absolut Vodka.
Other activities moving Kristianstad closer to its fossil-fuel free goal are to maximize energy efficiency and foster changes in behavior patterns. “Community planning is an important instrument to promote a Fossil Fuel Free municipality,” explains the case study. “The spread out population has resulted in high CO2 emissions from the traffic, which is why traffic measures are included in the project.” Apart from the work to introduce biogas as a fuel, Kristianstad is focusing on changing behavior – particularly the number of journeys made by car – especially since there will not be enough renewable fuel to fill current demand. “Mobility management” projects include encouraging carpooling and car sharing, as well as taking the bus (fueled by biogas) or riding bicycles to work. There is also rapid growth in rail transport. “Two new train stations are opening in the coming year, which will make it possible to live in smaller villages and not use cars,” says Erfors.
Two anaerobic digester facilities are operating in the Kristianstad region. One is at a municipal wastewater treatment plant. The other is the Karpalund plant, built in 1997 by the local Municipal Waste Management Company (Kristianstads Renhållnings AB) primarily as a treatment plant for waste from the local food industry. The Karpalund plant was the first facility in Sweden to codigest municipal solid waste from households (sorted into paper bags) and the food industry together with manure for production of energy and fertilizer.
“Two large slaughterhouses faced problems with disposing of their waste,” recalls Erfors. “That was what originally prompted the decision to build the digester. The municipal company that collects solid waste also owns and manages the digester.”
Average annual input to the Karpalund digester is 70,000 metric tons. That yields 40 gigawatt hours (GWh) of energy. Feedstock from the food industry accounts for 34 GWh; household waste contributes 4 GWh and manure is 2 GWh, according to Kristianstads Renhållnings AB. Roughly 63,000 metric tons/year of digestate is produced, the equivalent of about 1,000 metric tons of artificial fertilizer.
Household organics are set out in green bins. The city is encouraging more households to participate in the program, says Erfors. “We have increased our outreach and education. Right now, the household organic waste isn’t as clean as it should be, so the material is taken to another city that has the facilities to refine it, and then it is transported back to the biogas plant.”
Adding feedstocks from other local industries and growing dedicated energy crops have the potential to generate a significant amount of additional biogas – close to 300 GWh by one estimation. Biogas from the wastewater treatment plant contributes 8 GWh. All together, says Erfors, the two digesters present production generate enough biogas to supply 8 percent of the municipality’s total demand for vehicle fuel. The Absolut Company has plans to build a large-scale biogas plant linked to its ethanol factory. It will have the capacity to produce about 100 GWh/year, he adds.
BIOGAS FOR VEHICLE FUEL
Originally, half the biogas from the wastewater treatment plant digester was flared, causing concern on the part of public officials and politicians about degraded air quality. This ultimately led to a discussion about how to utilize the biogas. “That discussion in the mid-1990s led to an investigation of using the biogas as a vehicle fuel,” says Erfors. “It took some years, but the first filling station was in place by 1999. This was a relatively new process. Kristianstad was not the first, but the technology was by no means mature at that time.”
The local company Malmberg Water AB, Yngsjö, was awarded the contract to build the biogas refinement plant in 1998 to process 200 Nm3/hour of raw biogas. In 2006, given an increase in demand for the vehicle fuel, Malmberg was awarded a contract to build a second refinement plant with capacity to process an additional 600 Nm3/hr of raw biogas. That corresponds to around 10,000 liters of fuel produced every 24 hours. The gas is refined in a water scrubber process with circulating water as the absorption agent. The final gas quality is more than 97 percent methane. It is dried and compressed for transport to the filling stations.
E.ON Gas Sverige AB sells compressed natural gas and biogas at 33 public filling stations in the south of Sweden, including in Kristianstad. In some instances, a blend of biogas and natural gas is used to supply the fuel. The yearly volume is 300 GWh, replacing about 30 million liters of gasoline/diesel, says Roland Nilsson of E.ON, adding that about 40 percent of that amount is biogas. “Our target is to supply 2,000 GWh/year by 2020, of which biogas will account for 75 to 100 percent. We expect at least 5 to 10 new digester sites to start in a few years, with up to 50 new projects down the road. There are some where E.ON is a partner. Ultimately, the economy, incentives and fuel prices will decide the outcome.” E.ON also is a stakeholder in a gasification (methane) project using residuals from the forest industry as feedstock.
Kristianstad established a partnership with E.ON in 1999 to use the purified gas from the wastewater treatment plant as fuel for eight buses and some other vehicles. But it wasn’t until several years ago that more of the biogas from both the WWTP digester and the Karpalund plant were being conditioned into vehicle fuel. “Most of the biogas (70 percent) was used in the district heating system,” says Erfors. “However, our goal is to upgrade all that is possible because using biogas as vehicle fuel is worth much more monetarily than using it in the district heating system and also because biogas is the best presently available renewable vehicle fuel.”
All city buses in Kristianstad run on biogas fuel. “We have about 300 cars in the city that are equipped to use biogas,” he adds, “but there are 35,000 cars in total so the current share of the market is very small.” Grants to purchase a dual-fuel car expired in 2010. Private owners were able to receive 50 percent of the additional $4,000 cost required to run on dual fuels. There also were reductions for company-owned cars. Grants were available to build filling stations as well. When BioCycle spoke with Erfors in February, he noted that the Swedish Minister of the Environment was rolling out a new program to support environmentally-friendly cars. Up to $6,300 (40,000 SEK) per vehicle is available.
Skånetrafiken, the regional bus operator, has set a target of running its total fleet of 800 buses in the region of Skåne on biogas by 2018. “In addition to the new production we expect to come on line, biogas from other parts of Sweden may have to be brought in,” says Nilsson. Adds Erfors: “We definitely need more biogas production as we see demand for the fuel growing significantly.”
PROGRESS TOWARD FOSSIL-FUEL FREE
The district heating system is rolled out in major parts of the city of Kristianstad, and new areas continue to be added. The main boilers in the Alloverket CHP plant have capacity to produce 75 MW of energy. Several small-scale heating plants have been added over the years. In addition, the municipality has converted more than 40 boilers in public buildings, including schools, from oil to wood pellets. Households can receive grants to convert oil burners to run on wood pellets.
“Much of the wood for the pellets and biomass plant fuel comes from the wood products industry, e.g., from the manufacture of wood floors,” says Erfors. “The other primary source is forestry. The growth in forests in Sweden is significantly greater than the outtake, so the wood supply is sustainable.”
Reflecting on the progress made since Kristianstad put itself on a fossil-fuel free journey 12 years ago, one conclusion that can be drawn is that it is easier to reduce emissions from the heating sector than from transport, according to the case study on Kristianstad written for the European Commission. “Transports are the most difficult sector to adapt environmentally. This is according to behavior, differences in costs and access to different fuels.”
From Erfors point of view, however, all investments in bioenergy have proven to be very profitable. “Fuel costs for heating are very much lower when we do not use oil or electricity,” he says. “The ongoing debate is more between those who want more environmentally friendly transport, such as putting money in railways systems, and those who want to put money in building new roads.”
Nilsson acknowledges the challenges to economically aggregating enough organic wastes to achieve economy of scale in terms of digester capacity, biogas upgrading and compressing, building filling stations, etc. in a less urbanized region such as Skåne. But much of those logistics are being worked out. What’s left in large part is education. “The 180 percent reduction in greenhouse gas achieved when you digest manure and other organic wastes, use the biogas in vehicles and use the rest as biofertilizer is considered too good to be true by many,” says Nilsson. “But those are the facts.”