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Tech and Innovation
Hydroelectric Power Plants, commonly abbreviated as PLTA in Indonesian, are a form of renewable energy that has been utilized for over a century. This technology harnesses the power of flowing water, usually from rivers or dams, to spin turbines that then generate electricity. Around the world, hydropower is recognized as an efficient, clean, and sustainable energy solution. However, like other technologies, PLTA also comes with certain challenges and impacts, particularly concerning the environment and surrounding communities. This article discusses the benefits of hydropower while highlighting the potential impacts that need to be considered.
Simply put, hydropower works by converting the potential and kinetic energy of water into electricity. The process begins with the storage of water (usually in the form of reservoirs or dams) that holds a large volume of river water. Water from a certain height is then channeled to turbines. The pressure and flow of the water spin the turbines, which in turn drive generators to produce electricity.
The greater the height difference between the water source and the turbine (commonly referred to as the "head"), the more energy is generated. For this reason, hydropower plants are typically located in mountainous or highland areas that have rivers with steady flow and discharge throughout the year.
One of the main reasons hydropower has become popular is due to its many significant advantages over fossil fuel-based power plants. Hydropower is renewable, as the water used as its main resource does not run out as long as the Earth's hydrological cycle continues. Rain that falls in the mountains flows into rivers, and part of it is stored in dams to be used for energy.
Hydropower is also known as one of the lowest-emission power generation methods. In its production process, it produces almost no greenhouse gas emissions such as carbon dioxide (CO2) or methane (CH4), with emission intensity at only about 24 g CO2-eq per kWh, which is significantly lower than fossil power plants (IPCC & IHA)[Ref].
The operational costs of hydropower plants are relatively low once built. Unlike steam power plants that rely on coal or gas supplies, hydropower plants do not require additional fuel. This means the cost of electricity production can be cheaper in the long run.
In addition to producing electricity, many hydropower plants offer added benefits, such as flood control in downstream areas, irrigation water supply for agriculture, and clean water supply for household needs. Some reservoirs built as part of hydropower projects are even used as recreational and tourism sites for nearby communities.
In terms of energy supply stability, hydropower also has an edge. Unlike solar or wind power plants that depend on weather conditions, hydropower can operate consistently year-round if the water source is stable. This makes it a mainstay in the national electricity system as a base-load power generator.
Hydropower can also be utilized as an energy storage facility, particularly through pumped-storage technology. In this scheme, water is pumped back into the reservoir during periods of low electricity demand and then released to the turbines during peak demand, helping balance the grid load.
Although hydropower offers many advantages, the technology is not without negative impacts. One major criticism of hydropower is its effect on river ecosystems and surrounding environments.
Large dam construction alters the natural flow of rivers, which directly affects flora and fauna that rely on river conditions. For example, some migratory fish species may be hindered because dams block their migration paths. In addition, changes in water temperature and oxygen levels due to water storage in reservoirs can endanger aquatic life [Ref].
Beyond ecosystem impacts, large-scale hydropower projects often cause significant social impacts. Communities living in areas to be flooded for reservoirs often have to be relocated. This relocation involves not only physical displacement but also the severing of social, cultural, and economic ties built over generations.
In some cases, hydropower development can increase the risk of natural disasters, such as landslides or small earthquakes (microseismic events) due to changes in groundwater pressure. These risks increase if development is not preceded by adequate geological studies.
Although hydropower does not emit carbon like fossil power plants, recent research shows that reservoirs built in tropical areas can become sources of methane emissions[Ref]. This occurs due to the decomposition of organic matter at the bottom of the reservoir in anaerobic (oxygen-free) conditions, producing methane gas, a greenhouse gas much more potent than carbon dioxide.
Hydropower can also lead to unequal water distribution. If a dam holds too much water for power generation, downstream areas may suffer from drought or water quality decline. This inequality can impact agriculture, fisheries, and daily life for communities depending on the river.
Given the many benefits and challenges associated with hydropower, there is a need to balance national energy needs with environmental protection and social justice. Hydropower development should ideally be guided by the principle of sustainability: ensuring that today's energy needs are met without compromising the ability of future generations to meet their own needs.
An essential first step is conducting a comprehensive feasibility study. This study should not only focus on energy potential and technical aspects but also include environmental impact assessments (AMDAL) and social impact evaluations. Involving local communities from the planning stage is also crucial to ensure decisions reflect their perspectives and needs.
New technologies can also help reduce hydropower’s environmental impact. For example, fish ladders can assist fish in migrating past dams. Real-time water quality monitoring technology can also be used to manage ecological impacts in reservoirs and rivers.
Governments and stakeholders must be more selective in choosing hydropower development sites. Areas with high biodiversity or important ecological roles should be avoided. Alternatively, micro-hydro or mini-hydro potential in mountain villages can offer more environmentally and socially friendly solutions.
Hydropower is a key pillar in the energy transition toward cleaner and more renewable energy sources. Its advantages in efficiency, stability, and low emissions make it a logical choice in the context of the climate crisis. However, it is undeniable that the ecological and social impacts of large-scale hydropower development remain a shared challenge that must be addressed.
The solution is not to halt hydropower development but to design it more carefully. By integrating data-driven approaches, public participation, and commitment to environmental conservation, hydropower can serve as a tangible example of how energy technologies can deliver economic benefits while respecting life and nature.
Energy transition must be just. It is not enough to be clean—it must also respect the rights of local communities and not sacrifice the biodiversity we inherit. With a balanced approach, hydropower can continue to be a part of Indonesia’s greener and more inclusive energy future.
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