Solar Power and Solar Thermal Energy in Schools Detmar Kühl Page: 1
The Federal City of Bonn is home to the Secretariat of the United Nations Convention on Climate Change, or UNFCCC Secretariat, and to twelve more UN organisations focusing on sustainability. More than 150 non-governmental organisations working in the fields of ecology and development have also chosen Bonn as their seat, amongst them EUROSOLAR. The Lady Mayor of Bonn is the President of the World Mayors Council to combat Climate Change. It also hosts many international meetings. The International Conference for Renewable Energies, Renewables2004, was held in Bonn. Bonn is twinned with La Paz in Bolivia and Buchara in Uzbekistan, where it is involved in development work for solar energy use in projects in cooperation with schools that aim at raising environmental awareness. This work is carried out in two phases: Phase 1: Demonstration systems Phase 2: Fully operational systems supplying solar energy Page: 2
Selection criteria for schools Aspects related to teaching and learning about the environment Collection of financial operating data To address children / young people as a significant social target group in Bonn and in Buchara (education, vocational qualification) topical aims - to reach the parents - to influence the future behaviour of the children Page: 3
Alongside development activities in twin cities, Bonn continues to promote and increase the use of solar power and solar thermal energy at home. These efforts are jointly implemented by : The public sector The private sector In this presentation, we will look at the public sector, which in Bonn so far means the use of solar energy on school roofs and at a sports park. In accordance with a city council decision of 17 March 2005, the city s facility management department will increase the number of the existing solar power installations on some of the 700 buildings in its charge. Page: 4
Solar thermal energy is used in Bonn to supplement the water heating systems at four public open-air swimming pools. When heating systems are modernised, an appraisal is carried out to see if it is economically viable to use solar thermal energy. If its use is justified, more solar thermal systems will be installed in future. Page: 5
Existing and planned solar power installations 22 systems installed for teaching purposes 4 systems in 2005 9 systems in 2006 More systems are planned in 2007 using the latest thin-film solar cells Page: 6
Implementation using performance contracting Contractor finances Contractor builds The city pays contracting fees and earns the money back by selling the generated power to the public grid. Installed systems pay for themselves Benefits the environment without affecting the city budget Page: 7
The new systems built in 2006 have a total output of 123,000 kwh/a. The systems are provided on the basis of performance contracting. Contracting fee: 57,750 per year x 20 years = 1,155,000 Added revenue: 63,714 per year x 20 years = 1,274,280 Revenue covers expenditure Neutral impact on budget Page: 8
Based on these figures, the use of solar energy is appraised for all new construction and refurbishment projects. Another option taken into consideration involves renting out school roofspace to the private sector in order to increase the surface (area) used for solar power. Page: 9
Legal framework Germany s Renewable Energy Sources Act: 1. Requires energy utilities to buy power generated from renewable energy sources 2. Sets the price they must pay for solar power: 50.62 cents per kwh in 2006 Page: 10
Local industry Under the introductory arrangement, systems are financed on a performance contracting basis. The contractor is Stadtwerke Bonn the city utilities corporation and a local firm supplies the solar power hardware. This set-up has several benefits: Promotion of local medium size business Promotion of the regional industry Tax revenue for the local government Secures local employment More training places Page: 11
In its enforced structural change over the last few years, the City of Bonn has not only given greater political emphasis to the environment, it has also promoted environmental education. So far, solar energy has been used as a supplementary energy source rather than an alternative. The financial and performance figures are already making greater use of solar energy look more realistic, as fossil fuels become scarce. This is especially true when we remember that solar energy is only one of several alternative energy sources used in Bonn. Among other things, we also generate energy from biomass in the form of woodchips. Page: 12
Technical aspects Conventional high-efficiency solar cells Efficiency of single-crystal silicon wafers 14 18 % Efficiency of polycrystalline silicon wafers 13 16 % Service life > 20 years Page: 13
Thin-film wafers 100 times thinner than conventional wafers Lighter weight Cost less to make Service life > 20 years Efficiency 7 11 % The future lies in thin-film solar cells, despite their lower efficiency today. Page: 14
Use of roof-integrated solar panels Cuts cost of modernisation work Panels pay for themselves with power sold to the public grid Thin-film cells used for structural reasons Page: 15
Summary Performance contracting without impact on city budget Promotion of local business Support for globally operating firms in the development of advanced technologies Further progress on environmental aspects Direct effects Indirect effects Tax revenue and resource conservation Environmental awareness Page: 16