Hydroelectric power

As with my blog post on geothermal energy, hydroelectric power falls into the category of ‘effective but less widespread’ renewable energy sources. Despite this, hydro power has existed for over 100 years, which means that technology has matured and the efficiency of energy production has increased greatly, at ever lower costs. This means that hydro power, when effectively applied can produce huge amounts of electricity, in a sustainable manner – China’s hydroelectric power plants supply power to more than half of the country, reducing the reliance on fossil fuels. However, dams are not perfectly environmentally friendly. Requiring flooding of large areas of land, and huge construction projects, dams may seem like a brutal method of renewable energy production. The environmental effects stretch beyond just flooding and aesthetics however, with reservoir sediment building up over time due to soil erosion and human induced changes. This sediment can block up turbines and intake pipes, reducing its efficiency over time, and can become a secondary pollution to the environment if removed and not properly managed. This can be often overlooked in the construction of dams, and harms the renewable nature of the resource from both a production, and environmentally friendly standpoint.

As a result, work has been done finding a way to use this sediment, namely in construction. The Design for Six Sigma plan describes a method of turning masonry waste and reservoir sediment into fully useable bricks over a period of around a month. This in turn solves a multitude of environmental issues. Less waste is produced by the construction industry, reducing the high carbon footprint of cement production. Similarly, ecosystems are protected from the dumping of reservoir sediment. These two factors link together to create a much more sustainable method of development through the major sectors of energy production and construction. I found this method particularly interesting, as it seems to offer a win-win scenario for so many different actors, that is rare to find in the renewable energy debates, and it demonstrates how advancements in green technology can bring benefits to other, previously disconnected industries.

Although hydro power has been around for over a century, there is still scope for drastic changes to how we produce energy using water. For example, this study poses a new design of generator which could be applied to streams and smaller waterbodies without the need for damming. The study, undertaken in Japan notes that its application could produce millions of killowatts of electricity by adding the generators to small and medium sized waterbodies. The generator basically involves the oscillation of a vertical wing submerged in water, which can produce energy using a clever generator and maths that went so far over my head that it may has well have been another language. Despite this, the method does not require any part of the generator to be submerged other than the vertical wing, and as a result could be less intrusive on waterbodies, and may have a longer lifespan due to no need for water sealing. The method proposed is also reasonably efficient, at 32-37% efficiency, which is very reasonable for such a new method of renewable electricity generation. Obviously this is very much in a preliminary phase, and it is unlikely to be applied for a number of years, but it does demonstrate how even in well used and researched methods of renewable energy production, new ideas can be created that increase the utility of the renewable resource.

The final area I wanted to cover was looking at what currently exists in hydro power. Whilst it is useful to have an idea of future innovations in renewable energy, one must not lose sight of what the present situation is, and how effective our methods are. The Belo Monte dam, in Brazil aims to tackle one of the richest hydropower resources in the world, being set within the Amazon basin. However, as stated earlier, construction of traditional dams requires flooding of large areas, which in the case of Belo Monte, is 516km² of river, forest, crops and urban areas. This is clearly problematic for the Amazon rainforest, which has been subject to huge deforestation already. Therefore the impacts of the dams construction must be understood, both from a social and environmental perspective. Tropical rainforests hold the highest biodiversity indexes of any biome, and so flooding large swathes of land has a huge effect on species within the rainforest. This raises the question of conservation versus renewable energy, with both aiming to mitigate humanity’s impact on the planet. Understandably, the dam has come under a lot of flak for these impacts, and many see the dam as unnecessary considering the range of other renewable energy resources Brazil has to offer, even posing smaller dams as a less damaging, more efficient alternative. Indeed Berchin et al consider Brazil to be obsessed with large scale projects which are not as effective as pushing solar and wind power forward in the country.

The debates surrounding hydro power, and in particular dams such as the Belo Monte, make an interesting distinction between clean energy, which is carbon neutral, and sustainable energy. Overreliance on any one energy method seems to flag up negative consequences in one form or another, and hydroelectricity is a key culprit of this. With such drastic landscape changes required to put in effective hydro power plants, it is hard to see the electricity produced as sustainable. Yet with high yields, and a large research base, we should not write off hydro power, but see it as yet another weapon in the fight against fossil fuels and climate change. With careful planning, and innovations such as the oscillating wings, hydroelectricity is an invaluable resource, and will only increase in effectiveness in the future.