Life Cycle Analysis of telemonitoring system used for managing urban networks in the city of Martigny, Switzerland
by Mohamed Meghari Malik
Nowadays, the protection of the environment has become one of the most important challenges facing modern societies. The management of energy and natural resources in cross Cities is the main key to solving environmental problems. Unfortunately, local authorities have a great lack to overcome in the field of urban network management. In response to requests from municipalities regarding City management tools, the Centre of Competencies in Urbistics (CREM) has developed urbistic concept to manage Cities. This aims at reducing energy demand and resource utilization mainly by exchange of information, using primarily microcomputers and telecommunication.
Life Cycle Analysis (LCA) was performed using both input-output and process approaches in order to assess properly the environmental impacts and benefits of the monitoring system set up. The first task was to perform an inventory of the required infrastructure and to determine avoided impact on the environment and resources savings. Then, an environmental impact assessment was carried out using Missing Inventory Estimating Tool and SimaPro softwares adopting the Eco-indicator 99 method.
Figure 1: Urbistic concept: coordinated management of the urban network
The results of both approaches used were significantly different from each other. However, the results were clearly in favour of the urbistic approach. The telemonitoring system set up by the CREM, together with the City of Martigny, is very promising and could help Cities on their path towards sustainable development.
1. Introduction
The Industrial Services of Martigny (IS) supply drinking water, electricity, district heating, natural gas and cable TV for 15 000 inhabitants. In order to manage the entire urban network, the CREM supported by the IS and the Swiss Federal Institute of Technology in Lausanne (EPFL), developed a telemonitoring system using desktop computers and the cable TV network. This system enables managers to effectively control the City in terms of energy consumption and resource utilization, and gives local authorities an effective tool for decision making. Since 1987, twenty-six strategic sites have been equipped with control panels to measure the flow of energy and resources across the City. The information provided by the data processing networks are used to better understand the monitoring of installations and to optimize their use.
Figure 2: Example of data acquisition
After fifteen years of experimentation in the field of urban network management using telemonitoring system, spectacular results were found. Indeed, uninterrupted control of the water supply and district heating networks made it possible to detect anomalies that Industrial Services were no longer capable of correcting. Similarly, measurements of the electric power output carried out amongst certain subscribers made it possible to reduce the power consumption significantly. However, a question was raised whether the environmental benefit outweighs the impact produced by the necessary telemonitoring infrastructure.
This study is two folds. First, it aims to provide answers to questions set forth by researchers of the CREM concerning the effectiveness of the urbistic concept they developed. This would involve the quantification of the environmental impacts that were avoided due to resources and energy savings and those impacts generated due to the use, and set up, of the telemonitoring system. Secondly it aims to demonstrate the potential of the life cycle analysis method based on the input-output and process approaches used in the framework of this study.
2. Methodology
To achieve the goals set forth for this study, Life Cycle Analysis has been chosen as an environmental assessment tool. The first step of this study was to perform LCA according to input-output technique using Missing Inventory Estimating Tool (MIET) software. Input-output analysis is a macroeconomics technique that uses sectarian monetary transaction data to account for the complex interdependencies of industries in modern economies. This approach has, on one hand, the advantage to be complete and easy to perform. On the other hand, it has the disadvantage of high levels of aggregation making it impossible to perform an accurate analysis that takes into consideration the specificity of assessed projects.
The second step was to carry out an LCA based on the process approach. Process analysis is a technique in which the resource requirements and pollutant releases of the main production processes are assessed in detail. The application of this technique aims to take into account the characteristics of the region and the specificity of avoidable impacts in the City of Martigny. This approach was applied only for specific avoided impacts for which data were available. Different scenarios were analyzed for the drinking water and electrical systems.
Before applying the two life cycle analysis methods defined above, it was necessary to perform an inventory of the infrastructure used to set up the telemonitoring system. These include the hardware (PC, modems, sensors, cables etc.), and software developed specifically to make the system operational, as well as electricity and cable TV networks. Moreover research projects and work places required for the maintenance and the use of the telemonitoring system were also included in the inventory. Table 1 below summarizes the telemonitoring system inputs and the corresponding monetary funds. A detailed review of available literature on LCA allowed us to better understand some already quantified benefits. The remaining data were provided by CREM and IS personnel.
[not available]
Table 1. Telemonitoring infrastructure
Attractive benefits in terms of resource savings have been obtained using the telemonitoring system. For example, very high water flows have been measured in the skating rink compressors cooling system. A reduction in the flow to the compressors cooling system allowed the IS to reduce the water consumption by 388 800 m3 per year. Proper management of the heating power station, using the telemonitoring system made it possible to detect faulty operations in district heating network particularly in a periods between-seasons. The adjustments made to the system enables savings of 600 000 kWh of thermal energy. The table 2 below provides an estimate of the annual benefits by sector:
Table 2: Benefits
3. Results
The significant streams for which results are more precisely analyzed are as follows:
* Crude oil, gas and water consumption
* CO2, NOx, SOx, methane and heavy metal emissions The impact characterisation has been assessed using the Eco-indicator 99 method. Among the fifteen categories of the environmental effects proposed by the Society of Environment Toxicology and Chemistry (SETAC), the following are retained for this study: human toxicity, ecotoxicity, stratospheric ozone destruction, eutrophication/acidification, greenhouse effect, radiation, land use and nonrenewable energy consumption.
3.1. Input output life cycle analysis Results
-3.1.a. The infrastructure The results show that the work place and research projects predominate the effect for all impact categories. Electricity and cable TV also make a significant contribution to certain categories of impact whereas software has negligible impact. Among the various pollutants taken into account SOx, NOx and PM10 have a major impact on human toxicity. The high emissions of these pollutants, from dominant sectors are expressed through the high effects on the human respiratory system caused by inorganic substances. The pollutant inventory shows very high methane emissions in the work place sector which, in turn, has consequences on climate change.
Figure 4 : Impacts of telemonitoring system infrastructure
-3.1.b. The benefits Figure 5 shows that work places and water resource savings dominate the impacts. Drinking water resources are responsible for more than 39% of the impacts on the ecosystems, 24% on resources and 32% on human health. District heating and water tank have negligible impacts in comparison to other sectors.
Figure 5 : Avoided impacts
-3.1.c. The infrastructure Vs The benefits
The results obtained using input-output technique show that the environmental benefits carried out due to the savings made in terms of natural ressources, infrastructure and work places are largely higher than those due to the telemonitoring system infrastructure. The average ratio Benefits/impact is between 3 to 5, depending on the impact indicator.
Figure 6: Impacts of telemonitoring infrastructure vs benefits
4.2 Process life cycle analysis
Figure 7 : Comparison input-output results Vs process approach results
As mentioned above, life cycle analysis based on process approach was performed only to assess avoided impacts due to resources and infrastructure savings. The figure 7 above shows that the water supply network have a negligible impacts in comparison with other sectors. This result is in perfect agreement with the hydrogeologic characteristics of Martigny. The impacts related to district heating sector assessed with this approach are more representative of the really gas resources savings. The impacts caculated using process approach are 1 to 4 times less important
5. Discussion
Impact assessment results based on the Input—Output approach demonstrated that benefits made with respect to natural resources, infrastructure and work places, largely outweighs the impacts generated by the set-up and the use of the telemonitoring system. The avoided environmental impacts are four times more important than the generated impacts. Thus, the results obtained using Input-Output approach are clearly in favour of the urbistic concept. Nevertheless the results do not seem to reflect the geographic characteristics of Martigny, especially with regards to the water supply network. In fact, water in Martigny is collected in elevated areas and distributed to the city by gravity, therefore pumping stations are not required. Moreover, raw water quality is good and requires only basic treatment, consisting mainly of chlorination.
Since US economic databases are used to evaluate impacts, the Input-Output technique leads to uncertainties. Indeed, economic structure in the USA is different from the one in Switzerland. Besides, Input-Output method has a high level of aggregation, making calculations using this approach inaccurate. For example, calculation of impacts related to the gas or water resources savings, independently of the installation and infrastructure, are inappropriate and can not be performed accurately. The results obtained using the process approach are more specific and more accurate since it shows the real environmental benefits carried out using the telemonitoring system.
6. Conclusion
The results of both methods used in the framework of this study confirmed that the urbistic concept developed by the CREM is very promising. The use of information and communication technologies together with systemic approach allowed resource consumption within the City of Martigny to be greatly reduced.
To conclude this study we recommend the following:
1. The monitoring of electrical and district heating networks must be promoted in priority in all cities of Switzerland and elsewhere.
2. Management of the water supply network using the telemonitoring system must be promoted in Cities such as Lausanne, where drinking water undergoes a complex treatment and requires a significant supply of energy
Mon, Jan 5, 2004
Vision Journal