Energy Solutions for Off-grid Applications - Providing electric power and heat for regions without grid power or connected to a weak grid ...
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Energy Solutions for Off-grid Applications Providing electric power and heat for regions without grid power or connected to a weak grid interconnection www.german-energy-solutions.de/en
Imprint Publisher Deutsche Energie-Agentur GmbH (dena) German Energy Agency Chausseestrasse 128 a, 10115 Berlin, Germany E-mail: exportinfo@dena.de Internet: www.dena.de Status 05/2017 Design and implementation design@in-fluenz.de Lavesstraße 20/21, 30159 Hannover, Germany Cover image ©fotolia/Thor Jorgen Udvang Text Florian Schmidt David Schönheit Michael Kober All rights reserved. Any use is subject to consent by dena. All content has been prepared with the greatest possible care and is provided in good faith. dena provides no guarantee regarding the cur- rency, accuracy and completeness of the information provided. dena accepts no liability for damages of a tangible or intangible nature caused directly or indirectly by the use of or failure to use the informa- tion provided, unless dena can be proven to have acted with intent or gross negligence. This publication was funded by the Federal Ministry for Economic Affairs and Energy. 2
TABLE OF CONTENT
Table of Content
1. Table of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Development needs energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Regions affected by energy poverty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Energy solutions for off-grid regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Renewable energies: versatile and sustainable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Areas of application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Electricity generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Photovoltaics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Domestic use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Commercial and industrial use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Community-scale use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Wind energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Domestic use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Commercial and industrial use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Community-scale use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Small hydropower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Hybrid systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Off-grid island systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6. Heating and cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Solar thermal energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Domestic use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Commercial and industrial use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Community-scale use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Near-surface geothermal energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7. Generation of electricity and heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Bioenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Domestic use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Commercial and industrial use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Community-scale use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. Non-technical aspects of a successful project implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Public support and promotion schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Financing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Large-scale projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Small-scale and end-user financing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9. Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Photovoltaics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
How it works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Further types of PV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Solar thermal technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Operating principle and different types of solar collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Cooling systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3
Wind energy technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
How it works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Output of wind power plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Onshore wind energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Small wind turbines in off-grid regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Bioenergy technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Classification of bioenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Hydropower technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Technologies and applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Small hydropower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Environmental requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Geothermal energy technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Near-surface geothermal energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Storage and grid technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Batteries (electrochemical storage) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
10. German Energy Solutions Initiative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11. Addresses of institutions/associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Institutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Renewable energies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Solar energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Wind energy technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Bionergy technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Hydropower technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Geothermal technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Storage and grid technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Other institutions and partners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
German authorities and ministries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
12. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
13. Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4
TABLE OF FIGURES
1. Table of Figures
Figure 1: Diesel prices and electrification rates in selected African countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 2: Publication structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3: A schoolboy in Zambia studying after sunset using a solar lantern that was charged during the day. . . . . . . . . 10
Figure 4: The solar PV system installed at the Travessia Beach Lodge in Mozambique. . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 5: The grid-connected PV system on the roof of the Food Lover’s Market in Dar es Salaam. . . . . . . . . . . . . . . . . 11
Figure 6: Four wind turbines installed at the Diavik diamond mine in Canada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 7: Eigg Island, Scotland: the Scottish island, which has a population of around 100, has been operating
its own island grid since 2008. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 8: Modern island hybrid system for energy supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 9: Installation of the island hybrid system.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 10: Installation of a river hydropower turbine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 11: Mobile renewable energy hybrid system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 12: Solar thermal energy system for domestic water heating in a detached house. . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 13: Diagrams of a solar oven, panel cooker and parabolic solar cooker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 14: Parabolic solar cookers in Tibet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 15: Fresnel collectors installed on the roof of the building. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 16: Solar thermal rooftop installation of the brewery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 17: Ontario, Canada: the largest Canadian system to date for solar heating and cooling. . . . . . . . . . . . . . . . . . . . . 21
Figure 18: Large-scale solar thermal facility in the „Indian Silicon Valley“. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 19: Diagram of a photovoltaic solar cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 20: Rooftop PV installation with self-tracking system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 21: Composition of a solar collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 22: Wind turbine in Yzeron, Rhône Alpes, France, with a rotor diameter of ca. 7 m and a capacity of 10 kW,
which is achieved at nominal wind speeds of 11 metres per second. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 23: Unlike natural gas, biogas can be generated close to the end consumers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 24: Construction of a typical small hydroelectric power plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 25: Natural near-surface temperature distribution in the depths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 26: Horizontally installed geothermal heat collectors to provide heating for a single-family household. . . . . . . . . 34
Figure 27: Batteries can be integrated well into an off-grid hybrid system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5
PREFACE
2. Preface
If there are no fundamental changes to the current politi-
cal and technological situation, the International Energy
Agency estimates that 1.4 billion people will still be with-
out access to electricity in 2030. And by then, there will
still be 2.9 billion people who are not yet cooking with
clean energy – thereby exposing themselves to harmful
soot emissions and the risk of burns. These figures under-
line the magnitude of the task that lies ahead.
We must find solutions for the energy sector now in order
to facilitate economic development and protect the cli-
mate. Germany is already actively working toward an
international energy reform – for example, through
numerous pilot projects worldwide. Thanks to its decades
Safe access to clean and affordable energy is a central of experience and innovative companies in the field of
prerequisite for sustainable development and the fight renewable energies, Germany is well-equipped to face
against poverty. This is also anchored in the sustainable these challenges.
development goals laid down by the United Nations. After
all, over 70 % of people in the least developed countries This publication aims to provide an overview of the possi-
and in sub-Saharan Africa live without or with only inade- ble ways of providing, integrating and storing off-grid
quate access to the grid. But in more developed countries, electricity, heat and cooling from renewable energies.
too, and in the industrialised nations, there are consumers Practical examples and pilot projects provide applica-
who are not connected to the central energy supply sys- tion-based insights for the benefit of private users, small
tem, for example in the mountains or at sea. businesses, farmers, industrial corporations and munici-
palities.
In order to supply as many people and areas as possible
with clean and affordable energy, off-grid applications In order to achieve a sustainable supply of energy, we
working in conjunction with renewable energies present must share our knowledge and learn from one another on
an ideal solution. They provide an independent energy a global scale. Let us work together to achieve this goal.
supply, above all in vast rural areas or remote mountain
and desert regions, because they do not require access to
the grid and are not dependent on an energy supply com- Yours sincerely,
pany or subject to possible fluctuations in electricity
prices. At the same time, they are relatively cost-effective,
since the grid does not have to be expanded and no fuel is
needed.
Off-grid applications with renewable energies therefore
also contribute towards achieving global climate goals. Andreas Kuhlmann, Chief Executive
This is because they replace the outmoded diesel genera- Deutsche Energie-Agentur (dena)
tors which are usually used for off-grid power generation. German Energy Agency
6
DEVELOPMENT NEEDS ENERGY
3. Development needs energy
Access to energy is a fundamental basis for economic and Diesel prices and electrification rates in selected African countries
social development. Energy is a prerequisite for companies Local diesel price [US$-cents] (11/2014)
to manufacture and jobs to be created. It is required to 160
grow food, to prepare meals, to heat homes and schools, to 140
operate hospitals and to provide clean drinking water.
Energy also makes global communication and mobility 120
possible. Against the background of an increasing global 100
population, the global demand for energy is also growing.1
80
However, this is leading to declining reserves of fossil fuels
along with increasingly volatile oil prices. In many parts of 60
the world, biomass such as wood does not grow in suffi-
40
cient quantities to meet the human need for energy locally.
20
Regions affected by energy poverty 0
In 2014, nearly one fifth of the world’s population – 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
approx. 1.2 billion people – had no access to electricity. In Electrification rate [% of population] (2013)
fact, nearly two fifths (38 %) of the people on the planet –
around 2.6 billion people – do not even have clean cook- Figure 1: Bubble sizes correspond to the total population of the respective
country. Own illustration. Sources: dena Market Analysis 2014 based on
ing facilities and rely on wood, coal, charcoal, or animal
data from GIZ, EIA, IEA, World Bank (WDI).
waste to cook their food, breathing in toxic smoke. Over
95 % of the private individuals without access to electricity
live in sub-Saharan-Africa or developing Asia.2 Eighty-four Even in regions with a connection to the public electricity
per cent of those affected live in rural areas with no con- grid, sustainable access to electricity is not always guaran-
nection to the public electricity grid. For the households teed. If the grids are unstable, the manufacturing industry,
affected, this has a direct impact on everyday life: for the hotel and catering industry, educational institutions
example, these households cannot – or can only sporadi- and hospitals cannot work reliably and have to depend on
cally – reliably keep medicines cool and operate electric emergency generators.
lights and TVs or charge mobile phones. Diesel generators
are also not widely available or cannot be operated perma- Political institutions around the world are focusing on
nently due to price developments or restricted availability eliminating energy poverty. 2014–2024 has been declared
of fuel. That is why off-grid systems based on renewable by the United Nations (UN) as the “Decade of Sustainable
energy technologies can help countries with high diesel Energy for All”.3 If the over one billion people around the
prices and low electrification rates to support its popula- world who live in extreme poverty are to be able to achieve
tion and economy with a clean and reliable energy supply. the necessary development, off-grid regions must be
An example of countries in Africa is shown in Figure 1, connected to the public energy supply, viable alternatives
which is based on a global market analysis by the must be provided or the political and legal landscape for
Deutsche Energie-Agentur GmbH (dena) – the German this must be created.
Energy Agency.
1 BMWi, 2017
2 Se4all,2017 3 United Nations, 2017
7
DEVELOPMENT NEEDS ENERGY
However, there are gaps in the public electricity grid, not diesel generators. Additionally, existing diesel generators
only in developing countries and emerging markets but can be combined with renewable energy technologies like
also in industrialised countries, such as remote mountain photovoltaics. These so called hybrid systems can meet
regions, large forests or expanses of water. Here, too, higher demands, provide electricity reliably and save a
alternative solutions are needed to meet the energy considerable amount of fuel and therefore money. A pro-
requirement in these regions. Examples include the sea- ject supported by the Project Development Program (PDP)
sonal operation of gastronomic facilities such as ski huts, implemented by Deutsche Gesellschaft für Internationale
or the operation of scientific measuring stations. Zusammenarbeit (GIZ) GmbH shows that the advantages
for small-scale businesses can be extensive. The owners of
Energy solutions for off-grid regions a remote beach lodge in Mozambique installed a solar and
An off-grid energy supply – i.e. autonomous and inde- storage system, saving approx. 10,950 litres of diesel a
pendent of the public grid – is ideal in regions where it is year, with the initial investment being amortised after
not possible to connect to the public electricity grid or this three years. Besides that, improving the public image from
is not planned due to the high development costs to con- having a green and clean lodge goes far beyond the sav-
struct electric-line systems, especially in remote rural ings.
areas. In many cases, diesel generators provide the neces-
sary electricity in these areas and power individual homes GIZ’s Project Development Programme (PDP) supports
or village communities via a local mini-grid. Furthermore, German companies as they explore new markets that are
local electricity generation systems and storage technolo- promising but still difficult and barely developed. On
gies are installed as a supplement to the public electricity behalf of the German Federal Ministry for Economic
grid if recurring power failures affect the local reliability of Affairs and Energy (BMWi) and as part of the German
supply. What are known as back-up systems then bridge Energy Solutions Initiative, PDP advises companies during
the times in which no electricity is available via the public the various phases of market positioning and project
grid. development.
Autonomous photovoltaics and small wind energy plants, Besides the PDP, the broad range of applications for
as well as small hydroelectric power and bioenergy plants renewables is shown within the dena Renewable Energy
have a potential for application. The individual technolo- Solutions Programme (RES). Projects of the dena RES
gies are described in the chapter “Technologies”. Programme are carried out worldwide and serve as flag-
ship projects for renewable energy expertise in the fields
Renewable energies: versatile and sustainable of solar, wind, water, geothermal and bioenergy. All of the
Renewable energies facilitate a versatile use of regionally systems designed and implemented under this programme
available energy sources, both off-grid and as a local demonstrate the flexibility of German renewable energy
supplement to unreliable grids. They are low-emission and technology (including energy efficiency measures) and
low-risk with sustainable availability, they replace expen- know-how while working under local conditions and
sive imported fuels or save fuel being transported over meeting discerning user-specific requirements.
long distances, they protect the environment and human
health and contribute to peace-keeping. Lower investment The programme, coordinated by the dena, brings together
costs for generation and storage and high prices for fossil growing international demand for German renewable
fuels mean that renewable energy technologies are already energy technology and German companies with an interest
competitive in many regions of the world in comparison to in and the capacity to access attractive international mar-
domestic electricity prices or power generation using kets. The close coordination of dena ensures the installa-
8
DEVELOPMENT NEEDS ENERGY
tion of unique, customised systems. Furthermore, dena
initiates and oversees the transfer of the specific technol-
ogy and application know-how.
Renewable energy systems that have been carefully
designed, installed and professionally operated can pro-
vide power and heat reliably. To increase the share of
renewable energies in the electricity supply, storage capac-
ities and load management can provide the flexibility
needed and take on greater importance. The independence
from fossil fuel price trends facilitates the calculation of
operating and construction costs for renewable energy
installations. If the public energy supply grid is expanded
at a later date, autonomous systems can be connected
afterwards and the energy generated can be fed into the
public grid. In respect of promoting renewable energies, at
least 164 countries had renewable energy targets in early
2015, and an estimated 145 countries had renewable
energy support policies in place.4 Solar, wind, bioenergy as
well as hydropower can, either individually or combined,
provide energy for many applications independently of the
public electricity supply.
Energy in the form of electricity enables a lot of equipment
to be operated in rural regions, like providing the basic
infrastructure for using and charging mobile phones and
therefore facilitating communication. Photovoltaics,
hydropower, wind energy, biodiesel and biogas can gener-
ate electricity locally, be used directly to operate electrical
equipment or be stored if required. Thermal technologies
for using renewable energies facilitate hot water, heating,
cooling and drying. Depending on the technology used,
renewable energies can also be used directly for cooking or
for mobility purposes.
The following chapter is intended to provide an overview
of the range of applications of renewable energy technolo-
gies for electricity and heat supply as well as cooling,
accompanied by practical examples from various coun-
tries. Subsequently, the various technologies are eluci-
dated and afterwards the brochure concludes with an
analysis of the economical aspects and financing models.
4 REN21, 2017
9
AREAS OF APPLICATION
4. Areas of Application
Areas of application Domestic-scale use Commercial and industrial use Community-scale use Technologies
Phone and land mobile networks, Photovoltaic
mini-grids, street lighting and road
Mobile phones, lighting, Machines, computers, scientific sign illumination, maritime on-board Wind energy
Electricity supply computers, sewing measuring stations, water pumps, flour electrical systems, medical devices,
machines, radios, TVs mills, seawater desalination sea water desalination, standby Small hydropower
systems in urban and rural areas,
for unstable power grids
Bioenergy
Solar thermal
Hot water, room heating, Process heat, drying of agricultural Near-surface
Heating/cooling Hot water and building A/C
cooking, building A/C products, building A/C geothermal energy
Bioenergy
Figure 2: Publication structure. Own illustration.
The increased use of renewable energies and alternative Please note that generated electricity can always be con-
concepts of energy production is of great significance for verted into heating or cooling, e.g. by utilising a heat
single households, businesses and communities since, pump, or used for mobile application by transferring
after all, this is where a large part of the energy – in the electricity to a battery. Also, thermal energy can serve as
form of electricity and heating – is consumed. Renewable an energy source for electricity generation (e.g. steam
energies can provide a reliable, economical, cost-effective turbines, dish stirling CSP, etc.).
and sustainable energy supply. Photovoltaic modules for
generating electricity from sunlight and small wind plants However, only direct output will be considered, i.e. if a
can be combined intelligently in order to greatly reduce technology produces electricity or thermal energy as a
the annual electricity consumption. Other examples are direct output or if it can be directly integrated into a
fully automatic pellet heating systems, solar thermal mobile application. Hybrid systems are described at the
energy plants for generating heat or for air conditioning end of this chapter.
and heat pumps, which can utilise near-surface geother-
mal energy for heating. The following chapters give practi- Especially electricity-generating renewable energy systems
cal information on off-grid applications for each renewable can easily be upgraded by a storage medium, in particular
energy technology. batteries. This eliminates the necessity for simultaneous
energy generation and consumption and reduces the need
For each technology, applications will be described for for a diesel generator as backup. Generated electricity can
domestic use, commercial and industrial use and commu- be stored and used later. Storage technologies are men-
nity-scale use. For which uses each technology is applica- tioned throughout the chapter and are discussed in greater
ble is depicted in Figure 2. Domestic use will cover appli- detail at the end of the Technologies chapter.
cations for individual households. Commercial and
industrial use describes how technologies can be utilised Decisions about the correct implementation of RE projects
for factory buildings, commercial complexes or agricul- should take the costs of the whole project cycle into
tural facilities. Larger off-grid applications cover needs for account, i.e. from planning and implementation to the
multiple households or entire communities. This distinc- operation, maintenance and optimisation of the system, as
tion is important in order to decision-making a solu- well as the decommissioning and recycling of system
tion-oriented guide that facilitates decision making components. Reliable partners are essential in all phases
depending on the prevailing situation and requirements. of a project. And whereas the choice of quality compo-
10AREAS OF APPLICATION
nents can initially necessitate higher capital investment,
these costs are more than outweighed by the lower operat-
ing costs over the remaining term of the project. It is also
important to involve experienced partners during project
development and for O&M. Amongst other things, these
partners have on-site experience in implementing projects,
offer faster response times in the event of problems and
engage in the transfer of know-how in order to build up
local service infrastructures.
The deployment of renewable energy technologies is of
great importance in off-grid regions. Traditionally, unsus-
tainable, expensive and environmentally damaging forms
of energy generation are used in remote areas, such as
diesel generators. Renewable energies provide an alterna-
tive with many advantages.
Advantages of renewable energy technologies
¡¡ Reliable, sustainable and cost-effective energy
supply.
¡¡ Potentially lower operating costs for electricity,
especially when “grid parity” is reached or sur-
passed.
¡¡ Less dependence on imported energy and diesel
for example.
¡¡ Increasingly lower dependence on power grid and
lower energy costs.
¡¡ Local added value with new business models based
on sustainable and reliable energy supply.
¡¡ Reduction in CO2 emissions.
¡¡ Smaller ecological footprint through efficient and
climate-friendly use of energy sources in the
house.
¡¡ Higher quality of life due to less pollution, specifi-
cally better in-house air quality.
11ELECTRICITY GENERATION
5. Electricity generation
Photovoltaics The typical system of a domestic application consists of a
rooftop installation. New areas of application are found in
Photovoltaic systems (PV) are used to generate electricity the integration of PV systems into the building itself, e.g.
and are now one of the most environmentally friendly and by incorporating PV into the roof, facade or windows. For
efficient energy supply systems. German PV research and example, to meet the annual requirement of a four-person
industry companies are working on the development of family in Germany, an average household needs a PV
cell structures and production processes in order to fur- system with a peak output of 3.5 to 4 kW. Depending on
ther optimise application and reduce costs. In many coun- the PV technology used, this corresponds to a solar panel
tries, the cost of generating electricity from solar energy is surface area of about 35 to 40 m2 or more. Intelligent
comparable with the consumer price for conventional systems technology can be used to optimise the energy
electricity (“grid parity”), which can make self-supply consumption of households. By connecting to the grid, the
profitable compared to purchasing electricity. PV modules excess electricity can be supplied directly to the grid oper-
are especially suited for mobile applications due to being ator. Compared with an off-grid installation, the costs of a
easily scalable for every requirement. grid-connected system are lower, since it is not normally
necessary to store energy, which also improves the sys-
tem’s efficiency. Furthermore, electricity generation using
Advantages of photovoltaic electricity generation PV together with storage solutions can be carried out
¡¡ Reliable and cost-effective electricity generation off-grid (see “Storage and grid technology”). Mobile charg-
independent from an existing grid. ing stations or lighting systems are further applications for
¡¡ Easy to install, robust, modular design. private consumers.
¡¡ A wide range of applications from very small sys-
tems, such as solar-powered pocket calculators, to Small SHS of 1–10 W in size are called PicoPV systems
electricity generation for domestic usage and (PPS). These integrated systems consist of a small solar
large-scale installations with an output of several module and a battery and are particularly suited for pow-
megawatts. ering lights, radios or small mobile communication
¡¡ No moving parts – the installations have a long devices. This can bring about significant improvements for
service life. the population in off-grid regions. Children, for instance,
¡¡ Quiet, emission-free electricity generation. can continue to work on school assignments even through-
¡¡ Very environmentally friendly – silicon is the pri- out and after dusk.
mary material used in the manufacture of PV cells
and since it is the second most common element
on earth, it is comparably inexpensive to obtain
and the usage and disposal of silicon entails no
danger to the environment.
Domestic use
Solar home systems (SHS) supply households with elec-
tricity, e.g. to operate lights, radios, TVs, computers,
sewing machines, etc. They generally have an output of up
to 250 W and consist of a solar module, a battery and a Figure 3: A schoolboy in Zambia studying after sunset using a solar lantern
that was charged during the day.
charge regulator and – for greater loads – possibly also a
DC/AC inverter, which facilitates the operation of AC
devices. SHS are available as fully integrated, compact Commercial and industrial use
systems. The available output can be adapted to individual In trade and industry oftentimes the same PV-rooftop
requirements. Moreover, SHS are easy to install and installations as in private households are deployed, ena-
operate and have only low maintenance requirements. bling the roofs of factory buildings and commercial com-
Prepayment systems, which are used by various consum- plexes to be used to generate electricity in order to power
ers to utilise the generated energy and pay for it in small the facilities. This can be important even for grid-con-
units, can easily be integrated. nected businesses, since the manufacturing, hotel and
12ELECTRICITY GENERATION
catering industry, educational institutions and hospitals
need stable grids to operate reliably and therefore often Example of application: PV-diesel hybrid
depend on emergency generators during grid disruptions. Travessia Beach Lodge, Asantys Systems GmbH,
Larger-scale autonomous PV systems comprising multiple Mozambique
solar modules connected in series are called Solar Resi- ¡¡ Installed capacity diesel generator: 10 kVA
dential Systems. They provide power to hospitals and ¡¡ Installed capacity PV: 7 kWp PV system with a
schools, for example. lead-gel battery
¡¡ Module type: 27 x Solarworld, Sunmodule Plus SW
For the tourist and hotel industry, electricity supply by 260 Mono
renewable energy sources can have a huge impact on ¡¡ Inverter: SMA SB3600TL-21 (2x) und SI6.0H-11
business development, as examples from the Project (1x)
Development Programme (GIZ) show. The Travessia ¡¡ Yearly yield: 6,200–7,300 kWh
Beach Lodge decided to use solar power for electricity ¡¡ Yearly CO2 offset: 27 t
generation, instead of solely relying on an expensive, noisy ¡¡ Total cost: approx. € 30,000
and inefficient diesel generator. This reduces not only the
time and money necessary to obtain fuel (saving approx.
10,500 litres annually) but also the ongoing operation and
maintenance of the diesel generator. Conclusively, the Another example for the application of solar energy is the
initial investment will be paid off after only three years. RES project in Tanzania, a country with great prerequi-
Additional advantages are simplified operating of the sites for deploying PV, i.e. high levels of sun radiation. In
lodge due to a more reliable energy supply, reduced noise order to be more independent of high electricity prices and
level and benefits in terms of business reputation. reoccurring power outages, the Food Lover’s Market in
Dar es Salaam decided to invest in a grid-connected roof-
top PV system.
Travessia Beach Lodge, Mozambique
Keven Stander
“The construction of a PV system is a guarantee for
clean energy from sustainable sources - this saves
electricity costs and supports the green economy
agenda.“
Figure 5: The grid-connected PV system on the roof of the Food Lover’s
Market in Dar es Salaam. Deutsche Eco.
Example of application: PV rooftop system
Food Lover’s Market, Tanzania
¡¡ Installed capacity approx. 15 kWp
¡¡ Module type: 64 x Heckert Solar NeMo P 230 Wp
¡¡ Inverter: SMA Tripower 15.000 TL
Figure 4: The solar PV system installed at the Travessia Beach Lodge in ¡¡ Foundation: Schletter FlexXXL 4 x 16 modules
Mozambique. Asantys Systems GmbH.
¡¡ Yearly yield: 20,600 kWh
¡¡ Yearly CO2 offset: approx. 8–10 t
13ELECTRICITY GENERATION
Community-scale use The electricity-generating output varies according to the
Moreover, PV-assisted pump systems can provide water prevailing wind conditions. Ideally, the wind speeds are
for the rural population and cattle. These pumps are used measured over the course of a year in order to provide
to pump water from the spring to a higher water storage reliable forecasts for the future yield and facilitate the
tank when the sun is shining. This means the water supply selection of the best plant configuration.
is also available for immediate use at night, obviating the
need to use batteries. Furthermore, photovoltaics can
provide electricity for water purifying systems to supply The advantages of wind energy
drinking water via solar ultrafiltration, as well as seawater ¡¡ Wind energy delivers clean and climate-friendly
desalination by driving pumps and PV-operated reverse electricity, often at competitive prices.
osmosis. ¡¡ Wind turbines cover a wide range of applications
from a few kW to several MW.
Depending on the application, the modules are installed as ¡¡ Off-grid 10 kW turbines have the capacity to sup-
complete systems fully configured and wired with invert- ply agricultural operations and small villages.
ers, charge regulators, batteries and other devices. Photo- ¡¡ Electricity generation even at night depending on
voltaic systems can be designed as autonomous systems or the local wind conditions.
as grid-connected installations. In autonomous systems, ¡¡ Wind power plants form the ideal basis for an
the energy yield corresponds to the energy requirements. energy mix together with other renewable energy
If necessary, the energy is stored in rechargeable batteries power plants, whether for the public grid, for
or by means of heating water in a storage tank or supple- hybrid power plants or for a mini-grid.
mented by means of an additional source of energy
(hybrid system).
Domestic use
Small wind turbines can be used to generate electricity for
Wind energy households. Combined with storage technologies (see
“Storage and grid technology”) small-scale turbines can
Just like PV modules, wind energy systems only generate assure all the energy needed in one or more households,
electricity, which leads to a similar array of applications. e.g. for lighting, cooking, communication devices or other
However, there are important differences. As opposed to electric appliances. Small wind energy is actually used for
PV systems, which consist of connectable modules of special appliances and not widely used in the domestic
application-defined sizes, the capacity of wind turbines area. Wind energy can provide quiet electricity and thus
cannot be adjusted in very small increments. Additionally, support or – depending on the prevailing wind condi-
wind turbines have a higher minimum capacity. This tions – replace conventional electricity sources, e.g. diesel
limits the possibility to use wind energy for small, single generators.
applications, which is why wind turbines are much more
suitable for (partially) powering entire buildings, indus- Commercial and industrial use
trial complexes and communities. While PV can easily be Electricity for factory buildings and commercial complexes
integrated into buildings or applications, wind energy can also be provided by wind turbines, which can be
often requires extra space specifically allotted to it, which installed e.g. on or near buildings or at mines for electric-
also limits mobile applications. ity supply. For agricultural facilities, wind turbines can
provide the power for operating water pumps. With larger
Small to medium-sized wind turbines (with a rotor diame- sizes, wind turbines become increasingly relevant for
ter of up to 20 m and an output of approximately 100 kW) buildings with greater energy demands, such as hotels and
offer a variety of possible applications in off-grid regions. hospitals.
14ELECTRICITY GENERATION
An example for wind energy usage in industry is the Dia- Community-scale use
mond Mine in Canada. Four wind turbines were trans- With increasing size, wind energy can provide electricity
ported to and installed at the Diavik Diamond Mine in for entire communities. Wind turbines function well
Canada, 220 km from the Arctic Circle. For this challeng- within hybrid systems to complement the output of diesel
ing endeavour, trucks had to transport the turbine parts generators or other renewable energy sources, e.g. PV.
across 400-kilometre long “ice roads” to get to the inland
lake island on which the mine is located. The installed
wind park is expected to replace about 10% of the diesel
generator capacity, the only other energy source.
Example of application: wind energy
Diavik Diamond Mine, Canada
¡¡ Installed capacity: 9.2 MW
¡¡ Wind turbines: 4 x ENERCON E-70, each 2.3 MW
¡¡ Yearly yield: 17 GWh
¡¡ Yearly CO2 offset: 12,000 t
¡¡ Used for: mine operation
¡¡ Total cost: $33 million
Figure 7: Eigg Island, Scotland: The Scottish island, which has a popula-
tion of around 100, has been operating its own island grid since 2008. The
hybrid island system with an installed renewable generation output of 166
kW integrates solar energy, wind and hydroelectric power and battery stor-
age. Two diesel generators serve as a backup. Energy costs have fallen by
over 60 % since the conversion. Wind & Sun Ltd.
How rural areas can be provided with off-grid energy was
demonstrated by a dena RES project in 2015. HEOS
Energy GmbH installed two energy containers to supply
the Mongolian University of Life Sciences with electricity.
Mongolia has great prerequisites for exploiting wind and
solar energy. The containers hold a battery system as
backup and have PV modules mounted on top. Nearby, a
small wind turbine was installed.
Figure 6: Four wind turbines installed at the Diavik Diamond Mine in Can-
ada. Diavik Diamond Mine Enercon.
Figure 8: Modern island hybrid system for energy supply. HEOS Energy
GmbH.
15ELECTRICITY GENERATION
some hydroelectric plants provide higher flexibility due to
Example of application: wind-PV hybrid system their storage capability. Similar to wind energy, hydro-
Mongolian University of Life Sciences, Mongolia power plants have a higher minimum capacity and are
Wind energy: therefore not suitable for very small applications.
¡¡ Installed capacity wind: 15 kW
¡¡ Wind turbine: HEOS V15
¡¡ Inverter: Smart!Wind SW-10 Advantages of hydropower
¡¡ It has base load capability and can provide grid
¡¡ Yearly yield: 37 MWh
¡¡ Yearly CO2 offset: 25.9 t stabilisation: able to balance fluctuations in solar
and wind energy by virtue of its constant availabil-
PV:
ity and flexibility when the hydropower plant
¡¡ Installed capacity PV: 6.44 kW allows for water to be stored.
¡¡ Module type: 28 x 230 Wp Heckert Solar ¡¡ Hydropower can promote regions which are not
¡¡ Inverter: SMA STP 6.000TL-20 yet developed and connected to the grid and can
¡¡ Yearly yield: 9.74 MWh provide decentralised energy.
¡¡ Yearly CO2 offset: 6.8 t ¡¡ Proven technology.
Back-up system:
¡¡ Installed capacity and type, battery: Pb-Gel, 48 V
(24 x 2 V, 32 kW/16 k at 50 % DOD) A RES project in Colombia exemplifies how hydropower
¡¡ Inverter: 3 x SMA Sunny Island 6.0-11 can be used in off-grid regions. In 2015, Smart Hydro
¡¡ Installed capacity gasoline engine: 6.3 kW, Power GmbH installed a river hydropower turbine and a
4-stroke OHV, 400V/3-ph PV system to power the irrigation pumps of a local rice
farm. Previously, the pumps were solely operated by diesel
generators. Now, 1,000 m3 of water can be transported
from the river to the farm for one third of the cost. Thus,
the installation will be amortised within five years. The
setup of the system allows for modular expansion.
Example of application:
PV-hydropower hybrid system
Rice farm irrigation, Neiva, Colombia
Hydropower:
¡¡ Installed capacity: 5 kW
¡¡ Generator: Permanent magnet generator
¡¡ Inverter: TriStar MPPT-60-600V-48
Figure 9: Installation of the island hybrid system in Mongolia. HEOS
Energy GmbH
¡¡ Yearly CO2 offset: 9 t
PV:
¡¡ Installed capacity: 2 kWp
Small hydropower ¡¡ Modules: Yingli YL210P-26b
¡¡ Inverter: Studer XTM-400
Hydroelectric turbines also produce electricity and can ¡¡ Yearly yield: 2,815 kWh
cover applications similar to PV and wind energy or com- ¡¡ Yearly CO2 offset: 2.5 t
plement them in hybrid systems. The main difference is
the more constant electricity supply provided by hydro-
power plants, especially run-of-the-river plants. Also,
16ELECTRICITY GENERATION
There is a large market in complementing or replacing
existing diesel generators in rural areas with renewable
energy sources. Currently, there are an estimated 400 GW
of diesel capacity (> 0.5 MW) in operation.
Figure 10: Installation of a river hydropower turbine in Colombia. Smart
Hydro Power GmbH.
Rice farm irrigation, Neiva, Colombia Figure 11: Mobile renewable energy hybrid system.
Cándido Herrera Gonzáles, SENA (Servicio
Nacional de Aprendizaje): What are known as “energy containers” or “power contain-
“This project is important and valuable for SENAʼs ers” are mobile variants of hybrid systems. With these, a
“La Angostura” training centre, located in the Huila wind turbine, solar module, battery (usually lithium-ion)
region, wich is dedicated to training in the agribusi- and diesel generator are housed in a conventional freight
ness sector. This enables our trainees, especially our container. Therefore, the hybrid system can be deployed
experts, teachers and, supervisors, to get to know the quickly in changing locations.
companies and above all, to work with them.”
A further technology also used for off-grid-applications is
the fuel cell. Fuel cells generate electricity by a chemical
reaction. A fuel cell has two electrodes, one positive and
Hybrid systems one negative, called, respectively, the anode and cathode.
The reactions that produce electricity take place at the
Hybrid systems are autonomous off-grid systems which electrodes. Fuel cells are used for primary and backup
integrate more than one type of energy-generating tech- power for commercial, industrial and residential buildings
nology. They are used to supply off-grid power consumers and in remote or inaccessible areas. They are also used to
with energy, can meet higher energy demands and provide power fuel cell vehicles, including forklifts, automobiles,
electricity reliably, and are often used in off-grid systems buses, boats, motorcycles and submarines.
with bigger capacities (from 500 kW). The connection of
all electricity generators and consumers in DC operation
enables a system to be designed or expanded flexibly and
in a modular way using standard components. Common
configurations consist of photovoltaics with diesel genera-
tors (PV/diesel) or wind power with diesel generators
(wind/diesel). Optionally, conventional diesel can be
replaced with biodiesel. It is also possible to integrate a
hydroelectric power plant into the system. If the energy
requirement is high enough, larger hybrid systems, in
particular with a conventional diesel generator, are eco-
nomically attractive: they can run at lower costs than
plants operated entirely on diesel.
17ELECTRICITY GENERATION
Off-grid island systems The missionary station Sambo near Huambo uses a variety
Renewable energies can also be used to construct off-grid of technologies, including a PV-operated deep-well water
island systems. Such mini-grids can power facilities rang- supply system, a PV-wind hybrid system to power lamps
ing in size from individual buildings up to several small and refrigerators and a solar thermal system to heat water.
towns. In order to feed the electricity into the mini-grids,
an inverter has to first convert the electricity into alternat-
ing current (AC). Here, too, a storage module (e.g. a bat- Example of application: hybrid systems using
tery, see “Storage and grid technology”) is integrated to PV, wind energy, solar thermal energy
ensure that electricity is available when required, even Missionary station Sambo, Angola
during periods of insufficient solar radiation or low wind PV-wind hybrid island system:
speeds. As a rule, a mini-grid uses low AC voltage (220 or ¡¡ Installed capacity PV: approx. 12.5 kWp
380 V) with centralised generation and storage. The ¡¡ Module type: 16 x SUNSET Twin 130
installed capacity is usually between 5 and 300 kW; larger ¡¡ Inverter: SUNSET SUN3Grid® 6000 with Mini-
systems are also possible. Grid SUNisland
¡¡ Solar batteries: Bloc OPzV 2000, 2000 Ah, 48
If various technologies of energy generation – e.g. photo- Volt; Bloc Battery 500 Ah, 24 Volt
voltaics, wind turbines, hydropower systems, batteries and ¡¡ Installed capacity wind: 1 kW
diesel- or biofuel-powered electricity generators – are ¡¡ Wind generator: WG 1803
combined within an island system, a convenient, cost-ef- ¡¡ Used for: solar street lamps, 2 solar refrigerators,
fective and long-term off-grid electricity supply system can 20 lamps (damp room)
be established. These systems provide electricity in a
Deep-well water supply system
volume to meet the demands of relatively modern house-
(PV-operated):
holds (lighting, refrigerator, telecommunications, water
supply), to maintain public services (health centres, ¡¡ Installed capacity: 4.7 kWp
schools) and to develop small commercial operations. Solar thermal water heating system:
These systems are modular, can be expanded as electricity ¡¡ Solar collectors: SUNSET SUNblue® 25
needs rise and can later be connected to the public grid. ¡¡ Gravity storage: 300 litres, including a heat
exchanger
A RES project in Angola is exemplary of how a combina-
tion of different renewable energy sources can be utilised.
18Heating water for detached houses dem
HEATING AND COOLING
This is the most common application for solar thermal ener- me
gy worldwide. In Europe, these systems are designed to we
provide 100 % of the warm water required in summer and Ho
50–70 % in winter. They consist of a large collector with a 50
6. Heating and cooling surface area of 3 to 6 m2 and a boiler with a capacity of 200
to 400 litres for storing the heated water needed by a family
me
of four. Pr
In
Solar thermal energy sca
con
Solar thermal energy is used for heating rooms and water, um
for cooling or dehumidifying air, for process heating and tric
for drying purposes. It reduces energy costs for thermal sup
energy, saving on fossil fuels for heating. 1 to
5 the
(aq
Advantages
¡¡ Secure heat supply in comparison to, for example,
2 3 Pr
fire places or gas stoves. 4
¡¡ Reduced consumption of fossil fuels, considerable Th
savings in heating bills and more plannable heat- are
ing costs. ing
¡¡ Tried-and-tested technology that operates quietly So
and at a high level of efficiency. (in
¡¡ Simple technology with few moving parts and low Th
Solar thermal energy systems for domestic water heating in a detached house:
maintenance requirements. 1)Figure 12:– 2)
Collector Solar
Solarthermal energy
storage tank – 3) system for
Boiler – 4) domestic
Solar water
station with heatingsolar
integrated in a de-
stil
tached house:
controller – 5) Hot (1) collector,
water consumer(2) solar
(e.g. storage tank, (3) boiler, (4) solar sta-
shower)
¡¡ Generation and consumption of heating/cooling in
tion with integrated solar controller, (5) hot water consumer (e.g. shower) per
the same place, which reduces the need for infra- Source: www.solarpraxis.de
qu
structure. Systems for heating tap water
fut
Systems for heating
Solar cookers tap water the
concentrate are energy
typicallyfrom designed to heat
solar radia-
tion at the focal point of a parabolic reflector. Box-type 25
all domestic water throughout the summer period. In the
Domestic use designs (solar ovens) and panel cookers are also used.
winter months, the hot water is heated mainly by a heat gen- Pr
Heating water for detached houses is the most common Concentrating the sunbeams creates high temperatures at
erator (a boiler, usually operated with gas, oil, wood or a In
application for solar thermal energy worldwide. In Europe, the focal point, where a pot or pan can be placed to cook su
heat pump), which is supported by the solar thermal ener-
these systems are designed to provide 100 % of the warm food. Solar cookers have the advantage that they save on inc
water required in summer and 50–70 % in winter. They gy system and
firewood on sunny days.
the time This means
needed thatit.around
to collect 60 % of
Additionally, pr
the annual heatinguser-friendly
requirementsapplications
for heating water ate
consist of a large collector with a surface area of 3 to 6 m2 they are mobile, whichare
canpro-
be tw
and a boiler with a capacity of 200 to 400 litres for storing vided by the solar thermal energy system. The
deployed wherever needed. However, the cooker can onlycollector area
the heated water needed by a family of four. required
be used to do sothe
during depends on the
day, from weather
around an conditions in the
hour after sunrise
country in question.
to an hour before sunset. Ou
Systems for heating tap water are typically designed to Th
heat all domestic water throughout hot periods. In colder Combi-systems un
months, the hot water can be heated mainly by a heat
The solar collector area of combi-systems is larger. These op
generator (a boiler, usually operated with gas, oil, wood or
systems also help to heat the building in spring and autumn. op
a heat pump), which is supported by the solar thermal
Here, too, the collector area required depends on the weath- ma
energy system on sunny days. This means that around
60 % of the annual heating requirements for heating water er conditions in the country concerned and on consumer in
are provided by the solar thermal energy system. The
required collector area depends on the local weather Wagner & Co Solartechnik GmbH Wagner & Co Solartechnik GmbH
conditions and individual water consumption. Figure 13: Diagrams of a solar oven, panel cooker and parabolic
solar cooker.
Wagner & Co Solartechnik GmbH
19HEATING AND COOLING
ing solar energy. Within a dena RES project, Industrial
Solar GmbH together with Reach Renewables Ltd.
installed a Fresnel solar thermal system on the roof of the
corporate building of MTN to provide cooling for air
conditioning and processors.
Figure 14: Parabolic solar cookers in Tibet.
For purposes on a larger scale, e.g. community cooking or
large kitchens, the need for a physical separation between
the kitchen and the reflector arises. The reflectors can be
used to generate steam which is conducted into the Figure 15: Fresnel collectors installed on the roof of the building.
kitchen. An advantage of steam is that it can serve as a
storage medium.
Example of application: solar thermal cooling
Commercial and industrial use Mobile Telephone Networks (MTN), South Africa
Solar thermal energy has a variety of industrial and com- ¡¡ Installed capacity approx. 275 kWth (cooling)
mercial applications. It can be used for heating drinking ¡¡ Absorber: SCHOTT PTR 70
water (e.g. for hotels and hospitals), heating, cooling or ¡¡ Fresnel collectors: 2 strings, each 11 modules
dehumidifying the air, for providing process heat, for ¡¡ Collector surface: 484 m2
drying purposes, e.g. agricultural products, and for seawa- ¡¡ Yearly yield: 391 MWh
ter desalination. ¡¡ Yearly CO2 offset: 47 t
For industrial use (on a smaller scale also for households),
solar thermal energy, obtained through a collector, can Additionally there is enormous potential in providing
make a significant contribution to operating air condition- process heat for industrial applications using solar thermal
ing systems. The advantage of this technology is that the systems: some 30 % of the industrial heating demand is
need for cooling is greatest when the sun is most intense, within a temperature range below 100 °C. Solar thermal
whereby neither heat nor cold need to be stored over a energy can be provided either at supply level (industrial
long period. In addition to the immediate saving in fossil hot water or steam network) or at process level. The sys-
fuels, this also reduces the peak period power loads in tem technology required for high temperatures is still
summer. The increasing desire for a higher living standard relatively expensive; by contrast, process heating at tem-
and the trend of constructing buildings with large glass peratures of between 20–100 °C can be provided relatively
facades will probably increase the demand for environ- quickly and can be developed at comparatively low cost. In
mentally friendly air conditioning systems. They present a the future, it should be possible to achieve temperatures of
reliable alternative, especially in warmer countries in up to 250 °C.
which the power grids reach their limits as a result of the
power demand of electrically operated cooling systems at One example for the utilisation of solar thermal process
peak times. heat is the brewery Hofmühl brewery in Eichstätt, Ger-
many. A solar thermal system is supplying the brewery
In South Africa, Mobile Telephone Networks (MTN) with hot water. In order to increase the economic viability
makes use of the country’s excellent conditions for exploit- of the brewery, the production processes were adjusted to
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