Hot water brought to the earth’s surface includes arsenic, mercury, boron, antimony and salt, all of which may contaminate surface drainage water if not injected back into the earth, which fortunately is the customary practice.[i]

These fluids also contain a number of gases: CO2, hydrogen sulphide, methane and ammonia, all of which may contaminate the local atmosphere, although the CO2 emitted is a small fraction of the emissions of conventional fossil fuel plants. The hydrogen sulphide is also very small in quantity but may cause offensive smells locally.[ii]

Plant construction and drilling have been known to cause subsidence.[iii]

Many of Central America’s volcanoes are located within national parks and other protected areas, and this may be a potential source of conflict, as explained elsewhere in the website in the case of Costa Rica.

[i] KTH Research Project database (2005) ‘Arsenic in geothermal waters in Costa Rica, Central America’, http://researchprojects.kth.se/index.php/kb_7806/io_9338/io.html (accessed 12.07.11); Hartman Guido-Sequeira (2010) ‘Environmental Management in Geothermal Development: Case History for Costa Rica’, Proceedings World Geothermal Congress 2010.
[ii] Wikipedia (2011) ‘Geothermal electricity’, http://en.wikipedia.org/wiki/Geothermal_electricity
[iii] ClimateTechWiki, ‘Geothermal Electricity Production’, http://c,imatetechwiki.org/technology/geoth (accessed 19.07.11).