“Drought and the expansion of deserts have threatened the existency of over 1 billion people in more than 110 countries of our earth”. With these words, former General Secretary of the UN Kofi Annan had already warned the world in 2001 of the growing and alarming global problem of water scarcity for many of the world's population.
The United Nations predict that by the year 2025, two-thirds of the world‘s population - which will likely reach 6 billion by then - will lack access to drinking water, a problem that involves a life threatening undersupply to those affected, huge streams of refugees, growing urban migration and resource allocation conflicts that are already underway.
Progressive global warming is only making the problem worse. Although two-thirds of the surface of the earth is covered with water, only 0,02 % is potable. One of the many available solutions for tackling this problem, from a technical standpoint the treatment of sea and brackish water, hereafter referred to as sea water desalination, is one of the more promising. Successful large, centralized desalination plants are already in operation today. The use of these large-scale plants, whict can output as many as 1,000 cubic meters of fresh water per day, creates two basic problems:
- The majority of the undersupplied population (roughly 900 million) lives in rural areas with poor infrastructures and without access to fresh water from large plants, which is why a large number of small, decentralized plants are required.
- Desalination requires large amounts of energy, which in large scale systems is usually produced from fossil fuel sources. With respect to the total installed capacity in the world - 40 million cubic meters per day - CO2 production can be estimated at 200 million tons per year, which equates to one-fourth of the CO2 emissions in Germany.
In analyzing those regions with insufficient access to the “blue gold”, as drinking water is sometimes called, it becomes immediatly clear that renewable energy sources, especially solar, possess great potential for powering desalination systems. Current systems have yet proven to be economically and technically feasible however.