Hydro power has great potential; Many critics

Hydropower is climate friendly, but it remains a controversial energy source. It is not always the case, the renewable energy has a positive impact on the environment, such as some large dam projects have proven.

People have used for more than 2,000 years of water generated energy. Today electricity from water produces 15 percent of global electricity production - accounts for more than nuclear energy. Other renewable energy sources such as wind and solar energy, making only 4 percent.

Potential of water, however, is exhausted, and it is an attractive alternative to energy to CO2 levels.

Studies show that water power could meet almost all the planet energy. But that's not likely.

"Cost benefit only, according to André Böhling Greenpeace Germany doesn't". "Water as a renewable energy has on in the differentiated form - be considered on a case by case basis."

The different results of large dam projects illustrate the Böhling.

Old dam, new energy

Such a project in Honduras called the Esperanza provides hydroelectric plant an example of ideal as water and can be used effectively. The system draws on existing dam structures, takes a minimum amount of space, and the positive effects of energy production constantly are obvious.

Canadian businessman Ron Turner directs the project, which clean energy award has been nominated for the world. The plant is the first project in the world to sell its carbon offsets under the Kyoto Protocol of 1997.

But many large dam projects in environmental, economic and social disasters, to develop always much too intrusive on nature and society.

The Indian Sardar Sarovar dam and the three Gorges Dam in China symbolize environmental destruction and disregard for human rights instead of environmental progress.

Dams, flooding forests are particularly problematic. Over the years let the rotting plants, they leave large amounts of methane - a gas, has the worse effects on the climate than carbon dioxide.

Despite their dubious record, continue to large dams are built in India, China and South America.

Discussions to end

In much of the West, such projects are no longer possible.

"The debate on major new projects in Germany past", Harald Uphoff said by Germany's National Association of hydropower plants.

The growth opportunities that remain, likely on new methods and technologies. Experts test currently special buoys that can be hung up in rivers with little environmental impact.

Another focus is the often more than 50-year-old modernisation plants to generate more power, and the project in Honduras offered an example of how this can work.

Potential for Germany?

Accounting for 3.5 percent of Germany's electricity, hydropower is the country of the second largest form of renewable energy after wind. But the economic and ecological sense more water power facilities is a separating theme.

"In the long term, people not significant increases in water-power production, should expect," said Andre Böhling.

Others disagree with, as Uphoff, who argues that "such attitudes lead to a self-fulfilling prophecy."

Industry power argue that water at least might provide a third more power in Germany. Their hopes lie largely with miniature plants - small, decentralized systems with outputs up to five megawatts. Are responsible for 20 percent of hydropower in Germany.

"Such facilities are often enough provide energy for small communities", Uphoff said.

15,000 unused Web sites

The Federal Government supported a study 2008 used by German rivers and streams, the discovery of 15,000 embankments and barrages for power generation. Industry wants water to see facilities account for so much energy production as nuclear power plants, but ecological concerns stand in the way.

A 2009 adopted German legislators with incentives for electricity production in environmentally friendly ways. Those who are their small hydropower facilities with environmentally sound measures, such as the Fischtreppen, equip get more money for each Watt, which contribute to the power supply.