Environmental impact of hydropower

environmental impact of hydropower

Government Europa looks at the environmental impact of hydropower and its potential as an energy source.

The European Commission sees renewable energy as being able to play a major role in tackling climate change whilst also providing Europe with affordable and secure energy. In June this year, a 20-month process of debate on a crucial aspect of the EU’s clean energy package legislation was brought to a close with the announcement of an informal agreement on a binding 32% EU renewable energy target for 2030. While solar and wind energy have received much attention – and are already playing a significant role in Europe’s energy mix – other forms, such as hydropower, also have potential; and the environmental impact of hydropower demands closer examination.

The European Commission states that hydropower, energy derived from falling or fast-flowing water, is in general a mature technology; but that “further opportunities exist to optimise mechanical solutions to upgrade existing plants, improving [the efficiency and environmental impact of hydropower]”.

“In particular,” the Commission’s website states, “solutions to exploit energy production from little reservoirs or the development of hydro plants that can utilise small differences in the level of water (therefore not requiring the construction of massive dams) hold much promise.” As such, the Commission is supporting hydropower research and development by funding research projects which aim to reduce the environmental impact of hydropower and to demonstrate its potential.

A versatile, flexible technology

According to the International Hydropower Association (IHA), “hydropower is a versatile, flexible technology that at its smallest can power a single home, and at its largest can supply industry and the public with renewable electricity on a national and even regional scale. In terms of generation capacity, hydro accounts for eight of the world’s ten biggest power stations.”

The IHA list four broad hydropower typologies on their website – and it is worth noting that they can often overlap:

  • “Run-of-river hydropower”. The IHA describes this as ‘a facility that channels flowing water from a river through a canal or penstock to spin a turbine.’ In most instances, this is used to supply a base load of electricity as these facilities tend to have no storage capacity.
  • “Storage hydropower” usually sees a large system that uses a dam to store water in a reservoir, with the released water being used to turn a turbine and so produce electricity. “Storage hydropower provides base load as well as the ability to be shut down and started up at short notice according to the demands of the system (peak load). It can offer enough storage capacity to operate independently of the hydrological inflow for many weeks or even months,” the IHA says.
  • “Pumped-storage hydropower”. According to the IHA: “This provides peak-load supply, harnessing water which is cycled between a lower and upper reservoir by pumps which use surplus energy from the system at times of low demand. When electricity demand is high, water is released back to the lower reservoir through turbines to produce electricity.”
  • “Offshore hydropower”. Here, tidal currents or the power of waves to generate electricity from seawater, although the technologies used are less mature than in other areas.

The environmental impact of hydropower is substantially less drastic than that of traditional energy sources. By generating electricity from hydropower instead of coal, the IHA says, “in 2017 the world prevented approximately four billion tonnes of greenhouse gases – and avoided a 10% rise in global emissions from fossil fuels and industry. It also avoided 148 million tonnes of air polluting particulates, 62 million tonnes of sulphur dioxide, and eight million tonnes of nitrogen oxide from being emitted.” This is a result of a record 4,185 terawatt hours (TWh) in electricity being generated from hydropower in 2017, and of global hydropower installed capacity rising to 1,267 gigawatts (GW) in the same year, including 153 GW of pumped storage.

Environmental impact of hydropower

While considered to be a much more environmentally friendly method of electricity production than coal, hydropower nevertheless has an environmental impact. For instance, a recently-published scientific paper by researchers from Michigan State University (MSU), USA, included information on the social and environmental impact of hydropower dams, with the authors recommending the use of alternative methods for hydropower.

The paper called for the developing world not to use hydropower dams and instead generate hydropower for industry and livelihoods using other methods. This, they said, is because of the serious environmental impact of hydropower dams including:

  • Disrupting the natural ecology of rivers;
  • Damaging forests and biodiversity;
  • Releasing a high amount of greenhouse gases;
  • Disrupting food systems and agriculture; and
  • Deteriorating water quality.

The authors also cited the “human costs of large dams” as being “no less important,” noting: “The social, behavioural, cultural, economic, and political disruption that populations near dams face are routinely underestimated.”

To address some of these challenges, the necessary infrastructure for hydropower plants is often required to be hidden (and this also reduces the aesthetic environmental impact of hydropower plants). Indeed, recent years have seen an increasing amount of environmental regulations against the construction of aboveground penstocks come into force, meaning that so-called ‘hard drilling’ is required to link the different levels of the plants, for instance.

According to Community Energy Scotland, “Renewable energy projects often have a need for cables to be laid beneath roads, rivers or from shoreline sites to close off-shore installations. Directional horizontal drilling uses a mobile rig to drive an initial narrow tunnel through the ground, and then consolidates and widens the passage to take a sleeve which will provide a clear route for a cable or hydro penstock.”

This can be a challenge in itself; and the European Commission’s Environmental Impact Assessment Directive, which asks governments and companies to perform assessment checks on the environmental impact of hydropower operations before drilling processes are undertaken, must also be adhered to.

Under the directive, deep drillings need to be assessed in terms of the waste they produce, the effects that they could have on water and soil in the area, their use of natural resources, and any effects they may have on other projects in the area. Further, developers must adjust projects or introduce mitigating measures into proposals to ensure that no lasting negative impacts occur during drills.

There remain challenges with improving the technology that empowers excavations, but there are a large number of groups driving ecologically-friendly drilling innovation on both land and sea throughout Europe, working within the Commission’s directives to ensure that the environmental impact of hydropower can be investigated and mitigated.


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