The power of falling water has been used to produce electricity for over 135 years. As the world continues to move away from fossil fuels, surely it’s worth exploring the potential of one of the most established renewable energy sources we have! With that in mind, we spoke to Richard Taylor, CEO of the International Hydropower Association.
What are the main benefits of hydropower?
The beauty of the hydropower process is that the energy is highly concentrated in the water. The energy density of the technology is high and therefore, from relatively small-sized equipment, large amounts of energy can be produced. This is particularly true when you compare the size of hydro turbines to wind turbines, and the contrasting amounts of energy produced.
The other advantage of hydropower is that it can be switched on and off according to the requirements of the system that is being supplied. Providing there is storage capacity in the upper water body, it can be held back and then released when there is a gap in the electricity supplied from other sources.
What are the main types of hydropower?
All hydropower categories are important and relevant. We categorize hydropower into three components: run-of-river, storage and pumped storage, all of which have an important role.
Storage hydropower – when feasible – is hugely advantageous, providing flexibility of operations and other important water services.
Run-of-river projects have the advantage of creating less of a footprint particularly with regards to the land used for the upper water body. However, the operation of run-of-river projects, in comparison to storage hydropower, is less flexible.
Pumped-storage hydropower saves surplus energy and releases it at a point when it is needed but this process is not 100% efficient since storing the water also uses a portion of the energy generated. Consequently, pumped storage is used only when storage hydropower is not available, or as a way of complementing run-of-river hydropower projects and various other technologies that are unable to store electricity to match supply with demand.
Pumped storage has been around for a while, but it’s been gathering more interest in recent years, why is this?
The need to manage surplus energy in the system is becoming increasingly more complex. We have to strike a balance between decentralized and centralized methodology to back-up supply. In regards to the centralized approach, pumped storage is by far the leading technology.
Through pumped storage there is also no consumption or loss of water, because the two water bodies have closed systems. However, energy is lost and this occurs by pumping water to the upper body. Despite the energy loss, pumped storage is still the most efficient way of storing electricity, as current competing technologies are less efficient and have far less storage capacity. There is no utility scale of storing energy that competes with hydropower.
There are other technologies, and increasingly other fluids, that are being used to store energy but pumped storage still provides 99% of all electricity storage.
The future for pumped storage is bright, provided its advantages can be communicated well and the market conditions can be trusted by the potential developers. Unfortunately, energy policy-making has been erratic, and this has been a real deterrent. Only when policy-making orientates itself towards matching supply with demand will storage projects move forward. It appears the lights may have to go out on a few occasions before the increasing need for storage projects will be realized.
What are the main challenges in developing hydropower?
One of the main challenges facing the development of hydropower is the capital cost. Hydropower is probably the most extreme example of the challenge that all renewable technologies face: while you have very low running costs, the initial investment is very high. This is the opposite financial profile that you see in the fossil fuel sector, where initial costs and time frames are much less than those seen for hydropower developments.
Another challenge faced by hydropower is that, while it has a long life, it takes a long time to study and develop hydropower projects that are often outside the immediate need to deliver energy and not integrated into political horizons. Consequently, the development of hydropower requires a long-term, strategic view. Decision-making also needs to take into account the nexus of water, energy and climate, including the pressing need to manage freshwater resources.
What role will hydropower play in the future global energy mix?
The use of hydropower as back-up to other technologies will help to meet the demands for cleaner and more reliable energy systems. Hydropower plays an important role in more than 100 countries and is the main source of energy in about 50, yet it is rarely appreciated for the full range of services it provides.
Hydropower has just surpassed 1,000 GW of installed capacity globally and much of this has been achieved through an increasing number of stations in the developing world, while many other hydropower plants have been operating for decades elsewhere.
Extending the plant life of these assets will require investment, modifications and modernizations. This is the challenge faced by a large number of existing plants to maintain the benefits of renewable energy for the existing fleet of hydropower stations. There is also considerable potential for new development in all parts of the world, especially in Asia, Africa and South America, while there are substantial opportunities in Europe and North America too. Canada has a major role to play in further hydro development, particularly if North America is to move to a cleaner energy mix.
The opportunity to double the capacity is being discussed in several scenarios, and the way it will be developed will be largely country-specific. However, increasingly regional systems are becoming more important as cross-border collaborations move forward; this is driven by the desire for a clean and reliable electricity system, and the most efficient way of achieving it.