Economical "islands" in the high mountains

How high mountain huts can be operated more energy-efficiently

The Brandenburg House in the Ötztal - at 3277 meters the highest refuge of the German Alpine Club - is one of the mountain huts whose energy system Stephan Baur has examined in his work. © Stephan Baur
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In the German Alps alone, there are more than 350 mountain huts, which are far away from any public energy supply. Electricity and heat can not come from the valley but must be generated directly on site. A new study now helps to save costs: With proper maintenance of the batteries required for power storage, their lifetime can be quintupled. This significant cost savings may also be transferred to other "energetic islands" as in developing countries.

Many huts in the Alpine region are already equipped with diesel generators, solar, wind or even small hydroelectric power plants. The central building block is then an electric storage that has to smooth out the fluctuating energy supply with the weather as well as the day and season. "For the lead-acid batteries, which are mainly suitable for this purpose, then usually lies the economic vulnerability of the whole system, " explains Stephan Baur of the Max Planck Institute for Plasma Physics (IPP) in Garching. Because at replacement costs of around 15, 000 euros for the battery systems weighing up to 4.5 tonnes - not including the high costs for transport to the mountains - lifespan can be decisive for the cost-effectiveness of the entire energy supply.

Lower costs thanks to proper maintenance

In order to gain an overview of the energy supply in mountain huts, Stephan Baur visited 15 huts in the Alpine region for his diploma thesis, examined their power supply and asked the experience of the landlords. The aim was to keep the electricity costs as low as possible by increasing the service life and reliability of the expensive storage batteries. In fact, the storage battery only lasts for three years in some huts - but with proper care it would take significantly longer to operate for up to 15 years, resulting in significant cost savings.

In Cygnus X-3, a compact object (either neutron star or black hole) circles a hot, massive star with its accretion disk. The gamma radiation (illustrated here in purple) can be understood as the result of the interaction of relativistic electrons outside the accretion disk with the ultraviolet light of the massive star. Fermi sees more intense gamma emission when the compact object with its accretion disk is on the opposite side of the orbit. Walt Feimer / NASA / GSFC

As a major cause of premature aging of the battery, Baur was able to identify, in addition to water loss, frost and short circuits, especially the so-called acid-stratification: the battery contained in the battery separates dilute sulfuric acid in layers of different concentrations. This imbalance can lead to irreversible damage, for example to increased corrosion or accelerated sulfate encrustation of the electrodes, as well as lead fouling on the battery bottom.

The most important countermeasures are to charge the battery regularly and completely or to blow over the acid by blowing in air. In order to be able to reliably diagnose the condition of a battery, in particular also the acid coating, Stephan Baur developed a simple measuring procedure including evaluation software. The essential tips for maintaining a battery were summarized by Baur in a guideline for the hospital staff, which explains the optimal battery care in a short and simple way. display

New energy concept for the Westfalenhaus in the Stubaital

The importance of a properly dimensioned power storage for the entire energy system of a hut can be seen in the example of the Westfalenhaus in the Stubai Valley. For this hut, Stephan Baur konzip re-designed the entire electrical supply system after taking a detailed inventory of the current situation . He used a computer program developed in the IPP for much larger systems such as cities or whole countries, which optimizes energy systems from a cost point of view.

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The main energy source of the hut is a small hydropower plant, whose long bottlenecks in the spring are currently still bridging a diesel generator. However, according to Baurs calculations, the planned construction of a larger hydropower plant can be dispensed with if the Westfalenhaus is equipped with a sufficiently large battery system that can supply the surplus in the Night generated stream caches. Thus, the entire energy demand can be covered with the existing hydropower plant and the small photovoltaic system, ie exclusively with the help of renewable energy sources.

Transferable to other island locations

Regarding the entire energy system, mountain huts are little more than negligible niches. But they provide a good example of decentralized energy supply in general, says Stephan Baur. Worldwide, around two billion people are excluded from centralized electricity supply in populated areas, on islands and, above all, in the numerous remote settlements of developing countries: Systems that succeed in mountain huts, can be transferred to other Insellationsº without major changes. The results so far show the great potential of such autonomous systems. Further developments must reduce costs and increase the life expectancy of the components.

(Max Planck Institute for Plasma Physics, 13.03.2007 - AHE)