Renewable Hydroelectricity with Multiple Advantages

Hydroelectricity is generated by use of falling water from great height to turn turbines of a power generator. It is the most widely used form of renewable energy.

Worldwide, hydroelectricity supplied an estimated 715 GWe in 2005. This was approximately 19% of the world's electricity (up from 16% in 2003), and accounted for over 63% of electricity from renewable sources.

The advantages of hydroelectricity:

1. There is no fuel needed and it is renewable.
2. The generation itself does not produce carbon dioxide and is a 'green' process, does not result in air pollution, chemical runoff, or toxic waste impacts.
3. Labor and operating cost is usually low, as power plants are mostly automated.
4. Where a dam also supplies electricity, the ongoing revenue generated can easily offset the cost of dam construction within a short timeframe.
5. Large hydro dams, in addition to power generation as the primary function, also provide water related activities like irrigations, flood control, water consumption, marine and tourism activities, whereby increasing the viability of the project.

Hydroelectric power is usually very dispatchable and more reliable than others. Many dams can provide hundreds of megawatts within seconds of demand since the flow of water can be controlled. The hydroelectric dam on the Congo River at Inga Falls, near Matadi, Democratic Republic of the Congo. Photo origin:  Britannica

Negative Effects of Dam Construction

Dams can block fish passage to spawning grounds or to the ocean, although many plants now have measures in place to help reduce this impact.

Huge hydroelectric projects that require the construction of dams are therefore increasingly becoming unpopular and raise sensitive controversies.
Such projects are viewed as disruptive to surrounding aquatic ecosystems, forests biodiversity, human settlements and animal habitats. Therefore construction of hydro plant requires intensive and in-depth site studies, hydrological studies and environmental impact assessment and the displacement of people.

Extensive deforestation is needed to make land for dam site. So, although there is no GHG emissions due to non-usage of fossil fuel. Prior to the construction of the dam, deforestation is needed to clear land for construction. With deforestation comes the emission of carbon dioxide and methane gases into the atmosphere.

Mini and micro hydroelectric stations are gaining popularity for meeting smaller and isolated electricity demands especially in remote areas. Minimum environmental impacts are caused.

A mini-hydro electric station		Hydroelectric power engaging water's energy as it flows from higher to lower elevation, rotating hydraulic turbines to create electricity. (Pic: Enviroliteracy.org)

Today, China is a leading producer in hydroelectricity

One of the most controversial hydropower dam in the world is the
Three Gorges Project (TGP) along the Yangtze River in China
The USD 27.2 billion Three Gorges Project Dam is the largest water conservancy project ever built in China and in the world, with an installed capacity of 22.5 gigawatts

A large percentage of China's renewable energy is provided by this controversial Dam project. The Three Gorges Dam has been named among the world's top 10 renewable energy projects by the globally renowned science magazine Scientific American in July 2009.

The Three Gorges Dam for Hydropower in China: China-hiking.com (Photo origin: Xinhuanet)

China is also the world leader for small hydro with 38 GW in operation, out of 60 GW in global operations in 2006; and 145 GW in 2007. The utilizable hydropower of 2006 is equivalent to 50.7 billion tons of standard coal. Installed capacity is increasing at an annual rate of 17%. Implementation of rural energy development and provisions of incentives and funding is the main driver behind the 17% annual increase in installed capacity.

In the EU, compared to the wind power, market growth rates for mini hydropower are small with projected capacity reaching 13 GW in 2015.

China Dam Safety Under Pressure Ahead of Flood Season: Sina.com May 05, 2009
The Ministry of Water Resources of China warned that China's dam safety is under heavy pressure ahead of flood season as more torrential rain and extreme weather are expected in 2009 due to global climate change.

China has the world's biggest number of reservoirs. Special purpose inspections on dams show many of them are not in good condition. Dam safety is in a severe situation.

From 1999 to 2008, a total of 59 dams had cracks, 30 of which were caused by torrential rain and 20 by quality defects. In 2008,  3 295 dams and hydropower plants were damaged during the May 12 earthquake in Szechuan but none was breached last year.

37,000 reservoirs, or more than 40% have potential dangers, of which 3,642 dams are undergoing strengthening, and another 7,611 need to be reinforced immediately.

A general lack of early warning systems poses yet another threat to dam safety. For instance, 19% of key medium-sized reservoirs and 25% of normal medium-sized reservoirs are not equipped with rain water monitor systems. Immediate plans including dam reinforcement and reducing water storage capacity are needed for emergencies and dam safety.

References and related news:

China's Energy Consumption and Utilization: Easy-carbon.com
REN21 Renewables 2007 Global Status Report
Energy Matters: Hydroelectric Advantages and Disadvantages
Hydroelectricity | Clean Energy | US EPA
India Yet to Tap 80% of Small Hydropower Potential Jan 2009
The Role of Renewble Energy in China's Development: Worldwatch.org
Electricity: Energy Key to Africa's Prosperity