ENERGY BALANCE FOR SMALL WIND GENERATORS

HAMK University of Applied Sciences
Name of degree programme: Mechanical Engineering and Production Technology
Place: Kaartokatu 2, 11100 Riihimäki, Finland

Subject of Bachelor’s thesis: Energy balance for small wind generators
Commissioned by: Finnwind Oy

Supervised by: Tomi Sankari

Author: Vishesh Lohani
Year: 2011

ABSTRACT

This thesis is commissioned by Finnwind Oy. It is mainly concerned with the energy balance or energy pay-back of different wind generators manufactured by Finnwind Oy.The comparison of energy used by turbines in its life span with the energy produced by a turbine is known as the energy balance. Energy payback time means the length of time that a wind generator will take to produce that same amount of energy that was used to make it. This is used with renewable and non- renewable energy solutions to describe how long it takes for the device to generate the amount of energy that it took to make it in the first place. Tuule series wind turbine comprises of maximum 5. 3 kW turbines on a 18-27 m tower and is assumed to give energy of 12000 kWh annually in the sea shore and 5000 kWh on land.

The main objectives of this thesis are to describe the energy balance or energy pay-back period, calculation of wind turbines in different phases (production / transportation /decommission) as well as a comparison of three different poles (wooden / steel pipe /steel truss) on the basis of the energy balance.The pay-back period is calculated by the ratio of the total energy consumed by the turbine for manufacturing, operation, transport, dismantling, and disposal to the total annual energy production by the turbine. It is generally expressed in months or in years.The wind turbine comprises a generator, blades, tower, electronics parts as well as packaging materials. This thesis is carried out on the basis of a materials list given by Finnwind Oy. The amount of needed energy to produce any parts of the turbine is calculated based on the different online sources.

The pay back period of the different on-shore models is 1 to 1.5 years. But, the offshore models have quite high pay-back period. The pay-back period ranges from 2.5 to 3.5 years pay-back period for off-shore models. The wooden tower needs around 13000 MJ of energy for its life-span whereas the steel pipe requires 3 times more energy and the steel truss needs around 1.5 times more energy. The pay-back period can be minimized by increasing the efficiency of the generator. The quantity of materials and transporting distance also affects the large volume in the pay-back time. The mass installation of turbines plays a major role to minimize the period.

Keywords: Energy Pay-back, Life-cycle assessment, Wind turbine, Tower, Joules,

Pages: 27 p. + 8 XX p.