Jimmy OliapuramMarc Thurnheer

Roman GohlRamon SchniderAlexander Büchi

Group B2 October 2014

TASS – Report 1 - Target and conditions

Life cycle assessment of a wind farm

Group B2 TASS ZHAW

1 ABSTRACT

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2 INTRODUCTION

The energy consumption of human being is rising and rising without an end. This requirement has to be satisfied. But to reach this goal, a development of energy production is mandatory. This is absolutely feasible but for an expansion without large pollutant emission we must use renewable energy.

A typical renewable energy source is wind. There has been a rapid growth in the use of wind power in recent years because this renewable energy source is able to convert wind energy into electricity without significant emissions or resource consumption during operation. The technology of wind power has improved steadily and costs have been highly reduced. So all in all wind is a sufficient energy carrier and if you construct a wind power plant offshore, not many people are affected by it. But we also have to prove the environmental impact. An optional way to prove this impact is a Life cycle analysis.

3 THE LCA MODEL

The LCA model has been developed with the purpose of being able to assess all the energy used and the related emissions to produce different energy production technologies. This information can be import -ant, especially for the renewable technologies, where it often is mentioned that the energy used for the production is not paid back during lifetime of technology.

The values of energy and emissions from the materials which are used in the LCA stand for the total lifecycle of the material. So the sum is composed by producing, processing, working up, transporting and disposing of the materials. The system boundaries have an important impact on the LCA. You are able to choose on which part of the product you are looking at with the setting of the system boundaries.

With the LCA model you also have the possibility to check the energy production on pollutant, material disposal and waste generation.

All the data sets which are used for the LCA are from the website “ecoinvent.ch”. On the basis of those data sets the calculation are made with the program SIMAPRO.

Figure 1:

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Group B2 TASS ZHAW

Horizontal axis wind turbine of the alpha ventus wind park

4 GOAL AND BASIC PARAMETERS

4.1 SCOPE OF THE LIFE CYCLE ANALYSIS This paper presents a life cycle analysis of electricity generation by the offshore wind power plant “alpha ventus”. The area we are looking at is located in the north of Germany. The time frame of the LCA is limited to 20 years. We will split the project into manufacturing, usage and recycling.The technology used in the alpha ventus wind farm is called horizontal wind axis turbine and is the usually used wind turbine. The main function is to transform kinetic wind energy into electricity. So when the rotor, driven by the wind, is starting to rotate, kinetic energy is converted into electrical energy by a generator.

4.2 DIMENSIONSAlpha ventus is located in the North Sea about 60 kilometers away from the German coast. The purpose of the plant is to generate green energy for the industry and households in the northern part of Germany. The project consists of 12 horizontal wind turbines which are bundled into a wind farm. Every wind turbine performs an electric output of 5 MW which is equal to a total of 60 MW for the whole wind power station. The electricity generated by the wind turbines is summarized offshore and brought onshore by an electric cable. The feed cable of the offshore wind park is connected onshore to the existing electricity grid.This project should provide the costumers with ecological energy for a duration of a minimum of 20 years. The process from offshore wind energy to electrical energy in the households in Germany is starting with the convention of wind energy into mechanical and finally into energy to electrical power. This process happens in the inside of the wind turbine. The next step is the transformation of the energy for the transmission by cable to another transmission station onshore. In the last step the energy will be injected in the existing electricity grid.

Table 1General data about the wind farm.

Functional unit 1 kWh Delivered to the industry and households

Lifetime 20 Years The average technical lifetime of the whole wind farm.

Windmills in the farm 12 The number of power plants.Distance from shore 62 km The distance of the wind

farm to the shore.Nominal power 5 MW The power of one wind

turbine.

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Group B2 TASS ZHAW

Figure 1A map of the existing wind power plant alpha ventus.

4.3 SIMPLIFICATIONS AND ASSUMPTIONSThe annually produced energy should be assumed simply based on data from the internet (like perhaps operating hours and wind speed, or with existing datasets from alpha ventus). In addition the will be simplifications for the production, for example how much m 3 of concrete and steel are used for the base and the rotor. Also technical data of the existing wind turbines in alpha ventus can be used for the calculations.The LCA will end on the existing power grid, because it is already available and it still has the same task with the new wind power plant. Maintenance will not be included because the expenditure is not predictable. The material which will be used should be from the surrounding area.Another assumption is that the wind farm consists not only of raw materials but some parts are constructed out of recycled material. So in the end, the part which comes from recycling material at the beginning of the life cycle, is also going back into other new projects and processes at the end of the lifetime of the wind turbine. Because the transport routes are also very difficult to track these are also accepted. The onshore transports are realized with trains, trucks or as freight and the offshore transports are realized by ships.

Figure 2: Transport vehicles

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4.4 OBJECTIVE OF THE LIFE CYCLE ANALYSISBased on the "material flow analysis" the ecological costs and impact of the production, operation and disposal of a horizontal wind axis turbine will be analyzed in respond to their lifetime. The most important aspects of the Life Cycle Analysis are going to be emerged and interpreted.

The results of the LCA will be compared with a reference system. In the reference system there should be a CO2 balance for the generation of 1 kWh of electricity in conventional manner. We would like to choose the present Swiss electricity mix, so we would have a direct comparison of environmental impacts of Swiss energy production. In case we find a dataset of it. Another goal which is going to be mentioned is the relation between input and output from the system. An interesting object in the LCA is the percentage of recycling material in the input and output. As the environmental indicator we choose carbon dioxide, because it has the biggest influence on the global warming. The CO2 emission from the manufacturing, usage and recycling will be summarized and analysed. The goal in the end is to identify which process leads to the biggest global warming potential. Maybe we will also look at an additional one, if there is another environmental indicator affecting on the environment. But in this case we will have to make the calculation and evaluation first.

4.5 FUNCTIONAL UNITThe wind farm alpha ventus has a performance of 60 MW. The calculation of the energy production will be figured out in an additional part of the Life Cycle Analysis. So the functional unit is defined on 1 kWh of electricity. The reason for this decision is the simplicity. With this functional unit you are able to make easy comparison with other power plants. For example you get the possibility to benefit from advantages according to the Swiss electricity mix very easily because you have the same amount of the end product.

4.6 FLOW CHARTThe flow chart is split in three life cycle phases. The first part contains the production phase which is the biggest part with the most processes. After the production there is the use phase. In the use phase, there is only the production operation time which is estimated to have a small influence on the entire life cycle, there are not needed any resources at all. The last stage is the end of life phase. This period includes demolition and recycling. The system boundary is around all these three phase.

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Figure 3The Flow chart of the project.

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