| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1289280 | Journal of Power Sources | 2011 | 7 Pages |
SELF is a resource independent living and working environment. By on-board renewable electricity generation and storage, it accounts for all aspects of living, such as space heating and cooking as well as providing a purified rainwater supply and wastewater treatment, excluding food supply. Uninterrupted, on-demand energy and water supply are the key challenges. Off-grid renewable power supply fluctuations on daily and seasonal time scales impose production gaps that have to be served by local storage, a function normally fulfilled by the grid. While daily variations only obligate a small storage capacity, requirements for seasonal storage are substantial.The energy supply for SELF is reviewed based on real meteorological data and demand patterns for Zurich, Switzerland. A battery system with propane for cooking serves as a reference for battery-only and hybrid battery/hydrogen systems. In the latter, hydrogen is used for cooking and electricity generation. The analysis shows that hydrogen is ideal for long term bulk energy storage on a seasonal timescale, while batteries are best suited for short term energy storage. Although the efficiency penalty from hydrogen generation is substantial, in off-grid systems, this parameter is tolerable since the harvesting ratio of photovoltaic energy is limited by storage capacity.
Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Comparison of battery only off-grid energy system to H2 hybrid system. ▶ Onsite generated H2 is used as a fuel for cooking and fuel cell for electricity. ▶ Battery provides short term storage, hydrogen provides seasonal storage. ▶ H2 hybrid system requires 25% battery capacity of battery only system. ▶ H2 hybrid system is 40% smaller and lighter with same usability.
