Hydropower is a clean form of electric power generated from the mechanical force of flowing water. Usually, water stored in a dam is allowed to flow and the mechanical energy is used to run a water turbine. The turbine connected to a generator converts mechanical energy to electrical power. Hydropower is a renewable source, however the availability of appropriate water resources is a constraint. Water quantity, height of fall and flow speed determine the amount of power generated. There are two kinds of hydropower plants, pumped storage systems and Run-of-river systems. Pumped storage systems are large-scale plants that use excess power generated during times of low demand to pump water to higher storages and then reutilize them at times of peak demand (Clean Energy Council [CEC], 2). Run-of-river systems are mostly small-scale systems built taking advantage of the natural gravitational flow of rivers (CEC, 2).
1. Past Present and Future
Australia is a region with variable rainfall and there are only limited elevated areas. Due to high temperature and evaporation rates, Australia’s hydropower potential is only less (Harries). Hydropower was initially developed as early as 1881 in Mt. Bishoff, Tasmania to support the electricity needs of remote coalmines in Mt Lyell, Tin mines in Tasmania and copper mines in Queenstown. Australia installed hydropower plants within three years from the development of the first project in England (Harries). Soon several private companies took up hydropower projects, and in 1885 the Launceston municipality adopted hydroelectricity for household and street lighting, thus becoming a pioneer in utilizing hydropower for public utility. Following World War II, the focus shifted from Tasmania to Australia’s mainland, and the Victorian and New South Wales governments developed the Snowy Mountain hydropower and irrigation system in the Murray-Murrumbidgee river system (Harries). Snowy Mountain system comprises of 7 power stations including Australia’s largest hydropower plant of 1500MW capacity, as well as a complex underground power station. Snowy mountain project took 25 years to complete (Harries). However, more and more projects in Tasmania led to wide spread public opposition to large-scale projects, and the governments were forced to shift towards smaller schemes (Harries). According to Clean Energy Council’s (CEC) report 2011, about 8% of Australia’s total power and 67% of its renewable power is sourced from hydroelectric plants (1). Australia already has 124 hydropower plants in operation and further growth opportunity is only present for mini hydropower plants (CEC, 1). Further, the existing plants need refurbishment and upgrading.
2. Pros and Cons
Hydropower is renewable and has lower green house gas emissions when compared to coal fired thermal power plants. With dwindling fossil fuel resources hydropower could be used as a clean energy resource. While fossil power stations have only an energy efficiency of 25%, hydropower plants are 90% efficient (CEC, 2). Also, hydropower can be used handle fluctuating energy demands more effectively compared to solar or wind power (CEC, 2). Water can be stored and used as required, whereas wind and solar power cannot be relied for backup power storage. With proper maintenance hydropower plants can have a long lifetime and in Australia power plants even built 100 years ago are functional (CEC, 2).
Siting a hydropower project is very crucial for it’s functioning, and several projects in Australia could not takeoff due to strong opposition from local people. A Hydropower project if not planned properly can damage a vast area of the eco-system. It can expose low-lying, up-stream areas to flooding and affect river water quality (American Rivers). Dam construction might lead to loss in biodiversity, habitat loss, even extinction of certain species (American Rivers). Hence, even though hydropower is clean, the project should be planned and operated with utmost care, otherwise there is great risk to the environment as well as livelihood of people dependent on it.
3. Challenges existing in use
With climate change impacts threatening water availability and rainfall, developing a hydropower project could be very difficult in the near future. Also, while planning a large-scale project the impact of dam construction on upstream land areas, flora and fauna, as well as the impact of displacement of people has to be considered (Australian Institute of Energy [AIE], 6-7). Snowy mountain project lead to flooding upstream, and some rivers carry only 1% of water that they used to carry before the project’s commissioning (Australia.gov.au). Efforts are being made to restore the flow to at least 21% of its original capacity (Australia.gov.au). All these factors add to the cost of a hydropower project. Additionally, if there is flooding, rotting vegetation would emit methane due to anaerobic conditions, and this would increase carbon emissions. The dam construction and water storage can change ground water flow regimes as well (AIE, 6-7). Dredging the dam might be necessary, if there is excess silt deposition due to stagnation of water (AIE, 6-7). Thus there are several hidden costs associated with a hydropower project and a proper impact assessment is essential to develop an appropriate power generation project in the right location.
4. Prospects of developing in US
Unlike Australia, USA has huge potential and a large river network for generating hydropower. About 8.2% of total power generated in US is from hydroelectric power plants (American Rivers). There is widespread belief that US have tapped potential of all its water resources by 20th century itself, and no further dams can be built. However, with growing energy demand and requirement for clean sources, hydropower needs to expand. This can be done without building new dams. 90% of dams in US are not used to generate power and merely serve to hold water. By retrofitting these dams with power generating equipment, existing infrastructure can be used without affecting the natural eco-system, which has already co-existed with the dam (Spector). US can thus increase its hydropower capacity by 12 Giga watts i.e. 15% of the present hydroelectric power being generated (Spector). Further, US could focus on small run-off-river systems to supply power to remote communities. These systems are not connected to the grid, and can be used as backup sources. Run-off-systems also do not have any adverse impact on the water body, as it doesn’t alter its flow.
5. Conclusion
Thus from this brief discussion one can understand hydropower is an effective alternative to fossil fuel based thermal power. But, it has to be designed with foresight to avoid adverse environmental impacts and mitigation costs. Expansion of hydropower is possible in US without constructing new dams. While Australia with restricted hydropower potential aims to expand, US with sufficient existing infrastructure can tap the complete potential of its water resources to meet its future power needs.
Works Cited
AIE. "FACT SHEET 6: HYDRO ELECTRICITY." 2003. Web. 21 Feb. 2016.
<http://www.aie.org.au/AIE/Documents/FS6_HYDRO_ELECTRICITY.pdf>.
American Rivers. "Is Hydropower Clean?" 2014. Web. 21 Feb. 2016.
<http://www.americanrivers.org/initiatives/dams/hydropower/clean-energy/>.
Australia.gov.au. "The Snowy Mountains Scheme | Australia.gov.au." The Snowy Mountains
Scheme | Australia.gov.au. Web. 21 Feb. 2016. <http://www.australia.gov.au/about-australia/australian-story/snowy-mountains-scheme>.
CEC. "Hydroelectricity Fact Sheet 1." Oct. 2012. Web. 21 Feb. 2016.
<https://www.cleanenergycouncil.org.au/dam/cec/technologies/hydroelectricity/Hydro-Fact-Sheet-An-Overview-of-Hydroelectricity-in-Australia.pdf>.
Harries, David. "Hydroelectricity in Australia: Past, Present and Future — EcoGeneration."
EcoGeneration. Apr. 2011. Web. 21 Feb. 2016. <http://ecogeneration.com.au/news/
hydroelectricity_in_australia_past_present_and_future/55974>.
Spector, Julian. "The Untapped Potential of America's Hydroelectric Power." CityLab. 23
Nov. 2015. Web. 21 Feb. 2016. <http://www.citylab.com/weather/2015/
11/hydroelectric-power-energy-dams/416910/>.
