3.1 Introduction

There are many reasons to consider an increased utilization of renewable energy sources to supplement and replace part of the conventional fossil fuel-based energy production types that are most prevalent today. Besides the security of supply, an important issue is the future availability of coal, oil, and natural gas; finite reserves of these fossil fuels will be available for a period ranging from 50 to a maximum of 300 years. However, part of this supply of fossil fuels will provide society not only with electrical energy but also with an environmental impact as a result of the emission of carbon dioxide, a greenhouse gas. The emission of carbon dioxide decreases in the sequence of C (coal) → CH₂ − (oil) → CH₄ (natural gas), and these fossil fuels provide about 80% of the world's annual primary energy use. However, the current renewable energy sources (i.e., solar photovoltaics (PV), solar heat, hydropower, geothermal, wind, and biomass) provide only 2.7% of the alternative energy.

Looking from the perspective of industrial design engineering at the possibilities and opportunities to integrate sustainable energy technologies in products, several requirements toward product and integration can be identified. An energy technology is suitable for product applications if it meets the following criteria:

• It is sizable, preferably modular, allowing customization to its application and hence product integration.
• It can deliver power in a low power range, that is, less than 3 kWp.
• It doesn't require significant modifications of the environment of use once integrated in a product.
• It doesn't emit pollutants during use.
• If heat flows during use, it is at a level that is acceptable for users.

For the reasons mentioned here, we won't describe the following sustainable energy technologies in this chapter: biomass conversions, geothermal systems, or hydropower systems.

Hence in this chapter of The Power of Design the functional principles of various sustainable energy technologies that are relevant for product integration will be explained, namely, batteries (Section 3.2), PV solar energy (Section 3.3), fuel cells (Section 3.4), small wind turbines (Section 3.5), human power (Section 3.6), energy-saving lighting (Section 3.7), energy-saving technologies in buildings (Section 3.8), and piezoelectric energy conversions (Section 3.9).