Hydropower – the most substantial renewable energy source

In September of 1882, the first-ever hydroelectric power plant began operation, marking a milestone in the production of electricity. Nowadays, more than 16% of the worlds electricity demand is supplied by hydropower, making it by far the strongest within the renewable energy sector. This made us look deeper into hydropower and uncover exciting facts, contributing to the success and enormous growth over the last decades. 

Hydropower is a versatile, flexible technology that can meet the demand, ranging from single households to industry and the public, with renewable energy. Some of the worlds most colossal power stations, in terms of generation capacity, are hydroelectric power stations, with the biggest in Hubei, China, with a generation capacity of 22,500 MW, producing 101.6 TWh in FY2018. To give you a point of comparison, the yearly output of the “Three Gorges Dam” alone could power the entire country of Germany for 62 days.

Before going into more detail of hydro powers potential and capabilities, let’s have a look at the different types of hydropower stations, as well as some advantages and disadvantages. We distinguish between four main types of technologies; (i) impoundment, (ii) diversion, (iii) pumped storage, and (iv) offshore hydropower. 

An impoundment facility is the most common type of hydropower plant. It is typically associated with dams, storing river water to then tunnel through a turbine, whose spinning mechanism activates a generator to produce electricity. The amount of water running through the turbine can easily be controlled, therefore either be used to meet changing electricity needs or maintain a constant reservoir level. The most significant advantage of such a facility is the ability to provide a continuous level of electricity supply. Contrary, cumbersome requirements to build such a plant, e.g. (i) high initial CAPEX, (ii) lenthy authorization procedures, (iii) environmental assessment reports, and (iv) strenuous contruction and installation result in massive entry barriers to impoundment. 

Secondly, diversion, also known as run-off-river hydropower, channels flowing water of a river through a canal or penstock to spin a turbine, which in most instances may not require the need of a dam. Unlike an impoundment facility, diversion usually has little to no storage capacity, yet providing a continuous baseload of electricity. The biggest advantage of such power plants is the utilization of pre-existing natural conditions.

Another frequently used technique is so-called pumped-storage-hydropower (PSH), cycling water through an upper and lower reservoir. During periods of high electricity demand, water is released from the upper through turbines to the lower reservoir, generating power. In reverse, when energy demand is low, excess energy is used to pump water back to the top point, where the turbine acts as a pump. PSH provides the advantage of stability, storage capacity, energy balancing, and ancillary grid services such as network frequency control. Disadvantages, on the other hand, are high initial capital costs and infrastructural limitations. 

Lastly, offshore hydropower is a less established but growing technology, that uses the differences in water height, or the power of waves, both caused by tides, for power generation. Prerequisites, however, are a high tidal range, as seen on the north shores in France (10-15 meters). The flood, ebb tide and wave currents are used to drive the generators. The shift in peak capacity of around 50 minutes a day, caused by the tidal rhythm, may be seen as a disadvantage. Additionally, the lack of appropriate sites limits worldwide installations. 

A grand total of 4,200 TWh of electricity have been generated by hydroelectric power plants in FY2018 worldwide, the highest ever contribution of a renewable energy source YTD. The biggest contribution towards this incredible amount is coming from China, followed by Brazil, the US and Canada, combined accounting for about 50% of overall generation. By contributing 1.1% to the total amount of hydropower produced, Austria is amongst the 15 most important players in the wolrd. This figure may not seem like a lot. However, this accounts for about two-thirds of Austrias total gross electricity production. As a consequence, Austria is within the top ten countries worldwide when it comes to kWh per capita of hydroelectric power production. 

With all that said, let’s move on to some advantages of water-power production. Besides the obvious of it being green and renewable in operation, hydropower has excellent potential. For once, it is reliable, meaning there are relatively low fluctuations in terms of electric power ouput, which is why countries with relatively high resources of hydropower use it as a baseload energy source. Further, as mentioned above, the production of electricity using water is flexible, therefore at times of low power consumption, the flow of water can be reduced, whereas it can be increased at times of high demand. 

In the meanwhile, there are also some disadvantages embedded in the use of hydropower, such as environmental consequences, relatively high installation costs, limited reservoirs and the danger of draughts outlasting existing water reserves. 

Nonetheless, hydroelectric power generation is used as a major power source and has the potential to grow even further. Specifics of these advantages and disadvantages will be discussed in a future post, providing enough space for detailed analyses. 

What do you think of hydropower – what are the most promising aspects and what the biggest hurdles to overcome?