26 March 2009
Mountain hollows could be used to generate energy
Chinese researchers have developed a novel approach to generating renewable energy that
uses undeveloped mountains as “solar chimneys” to convert sunlight into electricity. Although
untested, such technology could potentially compete with clean coal power plants in terms of
cost and make significant contributions to energy supplies in mountainous countries.
Design of a standard solar chimney is simple in concept. Sunlight hits a collector at the bottom of the chimney,
heating up air that is then forced upwards through the shaft. The movement of the hot air drives a turbine to
generate power. However, in practice this approach suffers engineering problems – for maximum efficiency, the
chimney needs to be impractically tall (at least around 1 km in height).
To overcome this problem, the researchers propose that “chimneys” are drilled into mountains. One of these
chimneys would create a passageway to the top of a mountain, allowing hot air to travel upwards from a giant
collector at the bottom. The inside of the channel would be insulated and well rounded to ensure minimal loss of
energy and resistance to air flow.
The researchers calculated the potential energy outputs from such a system based on estimates from theoretical
models and a small prototype chimney just under 200m high. They estimate that a 1 km high mountain with a
channel of an equivalent height and a solar collector of 19.3 km2 could theoretically produce 210 gigawatt hours of
electricity every year. This would be at an average cost of around US $0.14 (0.011 Euros) per kilowatt hour (kW h)
during its 150 year life span. In comparison, the price of power generated by clean coal power stations is currently
around $0.11 (0.086 Euros) kW h, but is rapidly increasing due to the costs associated with removing harmful
gases and carbon capture.
A 1 km high mountain hollow would produce less than 1per cent of the electricity consumed annually by European
countries such as Spain and Germany1. A mountain hollow would also require a huge initial investment, due mainly
to the engineering challenge presented by creating the hollow and removing the unwanted rock residue. However,
the researchers say that in countries with high peaks and abundant sunlight, mountain energy plants could help
solve the energy problem. In addition, they note, making use of undeveloped mountain regions eliminates the need
to purchase large areas of land for solar power sites.
In mountainous countries such as China, such schemes might help to reduce dependence on fossil fuels and
contribute to meeting global greenhouse emissions targets. Some more mountainous regions of Europe, such as
the Alps, could also consider adopting the approach.
1
CIA. (2009). Rank Order – Electricity – Consumption. The World Factbook. Online: https://www.cia.gov/library/publications/the-worldfactbook/rankorder/2042rank.html
Source: Zhou, X., Yang, J., Wang, J., et al. (2008). Novel concept for producing energy integrating a solar collector with a man made mountain
hollow. Energy Conversion and Management. 50: 847-854. DOI: 10.1016/j.enconman.2008.09.006.
Contact: [email protected]
Theme(s): Climate change and energy, Environmental technologies
Opinions expressed in this News Alert do not necessarily reflect those of the European Commission
To cite this article/service: "Science for Environment Policy": European Commission DG Environment News Alert Service, edited by
SCU, The University of the West of England, Bristol.
European Commission DG ENV
News Alert Issue 146
March 2009
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