Question

Write about importance, environmental aspects, The current status and future projections for hydropower?

Answer 1

Hydropower is one of the most efficient power generation technologies, which are carbon free and use inexhaustible resources to produce the energy. The prime driver is the force of gravity and the water used to drive this power is non-destructive. Hydropower do not pollute the air we breathe in the way that the energy source does not produce any air pollutants. Unlike thermal power plants for example, there are no gaseous of fly ash emissions emitted during the production. The fact that hydropower often replace fossil-fired generation, it can therefore also be said that it is reducing the problem with acid rain and smog.

The economic valuation of environmental impacts of renewable energy sources (RES) has become an important issue in economics, especially because of the evident and increasing need to value damages caused by human activity either for awarding compensation or for planning purposes. It is also recognized the importance of the economic valuation of environmental impacts as an important requirement of cost–benefit analysis (CBA), which plays an important role in the public decision process. Economic valuation methods provide monetary estimations of environmental, health, and social impacts, so that they can be incorporated into CBA.

There may also be negative impacts. Lately the impact on the ecological aspects from the power plants has received attention. In the report from World Commission on Dams, it is stated that dams will have effects e.g. on the terrestrial ecosystem and biodiversity, the flow regime, migration of aquatic organisms, and can cause emissions of greenhouse gases. Hydropower affects the flow regime, migration of organisms and transport of nutrients and sediments.

The hydropower projects have several impacts on the environment. Water quality decline is one of the impacts of hydropower and water quality may be affected around a hydropower plant. Water discharged from a reservoir can be of a different composition to the water that is flowing into a reservoir. The other impacts of hydropower plant are migrations barriers. Hydropower dams impede the flows of rivers and thereby affect the habitat of various aquatic lives. Migratory animals require different environments for their different phases of their life cycle. Different stages are reproduction, production of juveniles, growth and sexual maturation. These different stages take place in different environments for different fishes. Even if hydropower is a renewable energy source it is not an energy source without GHG emissions. Greenhouse gas emissions can occur at three different phases hydropower plant (the construction, the operation and maintenance and the decommissioning of the plant). During the construction phase the emissions comes from the production and transport of the materials needed for the construction and from the work equipment.

Hydropower project also leads to sedimentation . The natural carried sediment from the usual natural flow will be negatively affected.When constructing a dam or hydropower plant, changes in the hydrological regime will follow. Changes in the hydrological regime is a significant impact from the hydropower plant. Due to a hydropower plant there will be changes in water level, timing and temperature, which will affect the surrounding terrestrial and aquatic ecosystem. The other biggest threats from hydropower projects are the loss of biodiversity and ecosystems that provides services that we cannot live without. The loss of valuable vegetative community types and loss of wildlife and habitats are resulted from land clearance and removal of natural vegetation

The nature and extent of the impact is highly dependent of site specific characteristics as well as on the type and dimension of hydropower plant . This implies that impacts affecting local communities must be assessed “on a case-to case basis” and, as such, it becomes an increasingly complex task to identify the most meaningful impacts. Therefore, in order to achieve this purpose a cross-referenced comparative approach is suggested and the literature on the economic valuation of hydropower environmental impacts can also be organized by the type of environmental impacts considered, and methodology used.

Renewable energy compared to conventional energy sources, i.e., sources of non-renewable energy from fossil fuels (oil derivatives, coal and natural gas) are considered to have a lower impact on the environment. Mitigation of greenhouse gas (GHG) emissions through low carbon power generation as a key contribution of small hydroelectric projects (SHP) towards sustainability. However, RES also have some environmental effects themselves that should not be overlooked. For hydropower, environmental impacts reported in the literature are frequently associated to biodiversity limitation, impacts on fauna and flora, landscape intrusion, water resource impacts, destruction of historical relics and visual impacts.

Valuation of environmental impacts

Two main types of valuation methods: (i) revealed preferences (RP), through which the goods’ value is inferred based on the observation of consumers’ behaviour, and (ii) stated preferences (SP), where the goods’ value depends on the individuals’ statements when asked how they would behave when faced with a certain scenario regarding non-market goods. These two types of methodologies have advantages and drawbacks. One major advantage of SP over RP techniques is the fact that they allow the elicitation of the total economic value (including use and non-use values) of the goods and services; and is applicable ex-ante and ex-post. RP requires the existence of a market context where the behaviour of the consumer is observed and preferences over the environmental good inferred, thus its application is only possible ex-post and it only allows the elicitation of the value attributed by users.

The negative environmental consequences of hydropower

Hydroelectricity is technically a “clean” energy source, but there are environmental ramifications of harnessing it for large amounts of power. Here are a few of the consequences that come with developing hydropower systems:

Damage to wildlife habitats and migratory paths

Constructing large storage or pumped storage hydropower plants involves blocking, diverting, or changing the natural course of river systems.

One issue that arises with blocking a river’s natural flow is the simultaneous blocking of important migration routes for fish. Many species of fish depend on inland rivers for reproduction; by blocking a river’s flow with dams, fish cannot reach their breeding grounds. Over time, dammed rivers lead to drastically reduced fish populations, which has negative implications for the health of river ecosystems as well as for human food stocks. Some hydropower facilities use fish ladders to help fish populations traverse dammed rivers, but these devices are rarely large enough to support massive migrations.

Land use

On a similar note, many large hydropower facilities lead to an altering of the surrounding landscape, especially around reservoirs created by damming rivers. Just as reducing downstream water flow can cause a loss of habitat, creating reservoirs to generate electricity in storage and pumped storage hydropower systems often cause upstream flooding that destroys wildlife habitats, scenic areas, and prime farming land. In some instances, this flooding can even force human populations to relocate.

Greenhouse gas emissions from reservoirs

While generating power by spinning turbines with water doesn’t directly use any fossil fuels or emit any greenhouse gases, several recent studies have shown that reservoirs created by damming rivers contribute significantly to atmospheric greenhouse gases. This is because organic material trapped in the reservoirs, such as dead plants, breaks down and releases gases like carbon dioxide and methane into the reservoir water.

Impacts on the environment are reflected by the effects of the water project, which in this case is the small hydro power plant. From the identification of impacts and their influence on individual components of the environment of the study area by the detection matrix, it is obvious that the most significant negative impacts during the construction activity will be from construction machinery, accompanied by noise, emissions, and dust. These stressors negatively affect habitats, climate, population and other components of the environment. The construction will also affect the soil layers as well as the quality of surface water. Direct negative impact on the environment during the operation of the SHP plant is not expected. For a comprehensive assessment of the expected impact in terms of its significance, nature, and duration, it is recommended to use the quantitative evaluation method. The assessment of the expected impacts of the proposed activity on the environment is presented as follows.

Action

The purpose of environmental mitigation requirements at hydroelectric projects is to avoid or minimize the adverse effects of development and operation. Among the mitigation actions dam removal is becoming a more frequently used management option all around the world. Dam removal is taking into consideration for old dams in need of renovation or small dams that are no longer used or have lost most of their reservoir capacity. Another point of view is that dams and the reservoirs have many ecological effects; the disruption of the movement of different organisms is probably the most important reason for dam restoration. Thereby, dam removal makes it possible for fish migration and fish species to shift from lentic to lotic, which in turn have the ability to migrate and reproduce in free-flowing water. Flow Regulations is also one the promising action for mitigating negative impacts of hydropower projects. In order to make the use of hydropower plants more compatible with the natural life of rivers, a minimum flow must be released so as to assure the preservation of the hydrological continuity of the river and the consequent conservation of natural habitat and ecological life. Minimum flow release means that you allow some flow below a hydropower plant with the dual aim of maintaining current water ecological conditions and partly also for aesthetic or recreational purposes on a watercourse distance, which would mostly had remained drained otherwise.

The problem with sedimentation in the surroundings of the hydropower plant can be mitigated by constructing sedimentation measures such as the construction of small-scale weirs to trap the sands and the particles that later can be manually removed. A direct approach to reduce the accumulation of sediment is to mechanically remove the sediments by periodic dredging. Biotope Adjustments is also other migration action. Adjusting the biotope through the creation of greater environmental heterogeneity, by using such as habitat adjusting measures, the biological diversity of the benthic fauna will be strengthened. Constructing migratory corridors are other mitigation actions for migrating animals. To facilitate for the migration of the species in the streams it is therefore desirable to construct corridors. Fish friendly turbine technology is an emerging technology that provides a safe approach for fish passing though the turbines by minimizing the risk of injury or even death . Aquatic animal Plantations is also other mitigation measures to reduce the negative effects of hydropower projects on the aquatic animals. Artificially manage the fertilization, hatching, growth and release of aquatic animal’s especially salmonid fish. To introduce planted fish to protect endangered species or reintroduce species that have disappeared may be of great benefit to the environment and the biodiversity .

Change in hydrological flow regimes, deteriorating water quality, migration corridors barriers, sedimentation, greenhouse gas emission and biodiversity loss are environmental impacts of hydropower projects. Dam removal, flow regulations, biotope adjustment, fish plantation, sedimentation measures, constructing migration corridors and fish friendly turbine are alternative action for mitigating the negative impacts of hydropower projects on the environment. Therefore, to meet the increasing demands energy and ensure sustainable development, various mitigation and enhancement measures have to be integrated at the early stages of project planning.