3 Method and case studies
3.5 Case study Hamburg
3.5.1 Introduction to Hamburg
The Free and Hanseatic City of Hamburg is located in the North of Germany (about 53.5° Northern latitude and 10.0° Eastern longitude) (see Figure 3.1). With about 1.7 million inhabitants52 it is the second‐largest city in Germany. Hamburg is one of the few areas in Germany where a growth of the population (particularly from migration) is expected. It is anticipated that by 2020 the population will increase to more than 1.8 million people (Statistisches Amt für Hamburg und Schleswig‐Holstein, 2008c).
There are about 960,000 households in Hamburg, resulting in a relatively low number of 1.8 persons per household. Since the total administrative area amounts to about 755 km2, the arithmetical population density is 23 p ha‐1. Yet, the actual population density varies greatly, reaching values as high as 180 p ha‐1 (Statistikamt Nord, 2010).
Hamburg’s climate is moderate and influenced by the proximity to the sea. Average air temperatures are between 2°C in January and 18°C in July and the mean annual rainfall
51 It should be noted that experience curves do not consider the effect of political and regulatory
frameworks (e.g. stricter emission standards), which can have a great effect on costs and market penetration (Öko‐Institut and Partner, 2004).
52 For the assessment the number of registered inhabitants in 2007 is used, i.e. 1,741,182 persons (Statistisches Amt für Hamburg und Schleswig‐Holstein, 2008b).
Hamburg
is 774 mm (Statistisches Amt für Hamburg und Schleswig‐Holstein, 2006). About 8% of the total area is water and Hamburg is characterised by several river courses within its town borders. The largest river is the Elbe River, which has its source in Czech Republic and discharges into the North Sea about 100 km downstream of Hamburg. The port, which is the second largest port in Europe, is considered to be one of the most important economic drivers in Hamburg. Water is an important element for the town for recreational and particularly industrial purposes. The quality of the surface water is therefore a major concern and efforts have been made on various levels to improve the water quality53.
Figure 3.1: Location of Hamburg
(Based on maps from Quizimodo and David Liuzzo, Wikimedia Commons)
Agriculture is practiced on about 25% of the total area of Hamburg, particularly for fruit‐growing and flower farming. Yet, the economic importance of the farming sector is rather marginal. The surrounding area however, is shaped by agricultural activities, thanks to fertile soils. In the Hamburg Metropolitan Region, which covers about 20,000 km2 including the city itself, agriculture is the greatest user of land area (Drücker et al., 2006).
53 Examples of relevant initiatives are the River Basin Community Elbe, which is concerned with the European Water Framework Directive, and the combined sewer overflow programme of Hamburg Wasser implemented in the last 20 years.
In the past, drinking water supply for the town was sourced mainly from surface water, but since 1964 only groundwater is used. To fulfil the water demand, groundwater is also extracted from areas outside the town borders; these areas include ecologically sensitive areas. The increasing demand is the reason for disputes between Hamburg and the surrounding communities (Stemmler, 2009). Eighteen treatment plants for groundwater treatment and distribution exist. With a total length of more than 5,500 km, the water distribution network is one of the largest in Germany distributing about 350,000 m3 water every day (Leonhardt, 2005). Water consumption in households has declined due to the introduction of water meters and water‐saving installations, to about 107 l p‐1 d‐1 (Hamburg Wasser, 2007) and is expected to further decrease in the future (Maass, 2008).
Hamburg was the first city on the European continent where a sewer system was implemented. The sanitation system in Hamburg in the 19th century was similar to that of other European cities, namely a system of pit latrines, soakways and open disposal.
After a disastrous fire in 1842 a complete renewal of the inner city was initiated, including the construction of a sewerage system. Starting with 12 km of sewers at that time, the sewer system in Hamburg now totals about 5,400 km.
Treatment of wastewater though, was neglected for a long time, until a Cholera epidemic in 1892 forced the town’s decision makers to start thinking about treating the wastewater formerly discharged as raw sewage into the water courses. Initially several distributed treatment plants were installed. In the 1960s two combined treatment plants in Köhlbrandhöft/Dradenau gradually made the decentralised plants redundant (Eich and Wierecky, 2002). Nowadays, 99.8% of the inhabitants are connected to these plants.
The remaining inhabitants rely on on‐site treatment of their wastewater (BSU, 2009). In 77.5% of the sewered area totalling 407 km2, separate sewers have been installed, while 22.5% of the sewered area discharges into combined sewers. The treatment plant currently treats about 168 million m3 of wastewater every year, using physical, biological and chemical treatment processes. About 35% of this volume is from rainwater and 8% is from surrounding communities (Hamburg Wasser, 2007). The effluent is discharged to the Elbe River. Sewage sludge is anaerobically digested, dried and incinerated in a mono‐incineration plant installed in 1997.
Organic waste (kitchen and garden waste) is currently collected separately only in some parts of the city (about 22% of the households), since home composting is recommended in areas with plot sizes larger than 600m2 (BSU, 2007). In addition, lack of space for separate collection bins is cited as a restricting factor in the more densely
populated areas. The separately collected organic waste is transported to composting facilities where compost (for sale at a price of 13 € m‐3) is produced54.
Hamburg citizens pay 1.57 € m‐3 for their drinking water plus a basic fee of about 2 € per month (costs for 2009). This is in line with the average drinking water fee in Germany of 1.85 € m‐3 (ATT et al., 2008). On average, German households spend about 0.5% of their household income on drinking water. Sanitation costs in Hamburg are coupled to drinking water consumption and amount to 2.67 € m‐3, which is a bit higher than the average German fee of 2.28 € m‐3 (ATT et al., 2008). Households that have their organic waste collected by the public cleansing service pay a fee of about 13 € per month, which is considerably less (roughly 20%‐30%) than the equivalent collection of other household waste (SRH, 2009).
In 2006 Hamburg’s water and wastewater utilities merged into Hamburg Wasser. In order to be prepared for future challenges and to develop export services, Hamburg Wasser pilots several innovative water and wastewater technologies. These include, for example, the feed‐in of biogas into the public gas supply network (Schurig, 2009), heat recovery from wastewater sewers (Werner and Augustin, 2009), and separate collection and treatment of blackwater (Schonlau et al., 2008). Flooding from increased rainfall intensity due to climate change, as well as increasing impervious surface areas, presents a further challenge that is important in the Hamburg context. Rainwater management is however, only marginally addressed in this thesis.