Hydropower and the Mekong River

My last post outlined a number of studies highlighting the negative environmental impacts of hydropower, particularly in tropical regions. When looking into this subject, one case study which really stood out for me was the impact of hydropower in the Mekong River.

Upstream in China, seven dams exist with plans for up to 21 more. Downstream in Cambodia and Laos, there are another 11 proposed, with the controversial Xayaburi Dam in Laos nearing completion. The Mekong is of particular importance because of its rich variety of aquatic species;  it is a biodiversity hotspot, second only to the Amazon River. Not only is the Mekong of huge environmental significance, there is a large population that live around the Mekong, relying on subsistence fishing for survival. The proposed construction of these dams has therefore raised tremendous concern which in turn has led to research on the impacts of increased hydropower production on the river.

In 2012, Ziv et al. (2012) conducted a study into the six different dam scenarios that had been outlined by the Mekong River Commission. The results concluded that biodiversity and productivity would be most severely affected if dams in the upstream tributaries were constructed, however there would be a far lower impact on biodiversity and subsistence fishing with the construction of the proposed downstream dams. 

Another environmental impact of hydropower in the Mekong is highlighted in Anthony et al's  (2015) study.  Erosion in the Mekong Delta is a significant consequence of the dams that have been constructed upstream; because sediment has been retained behind the dams, sediment supply to the delta has been reduced. As a result, circa 5km2 of coastline was been lost between 2003 and 2012.

The Mekong Delta, Vietnam
Source: Britannica

There are, of course, benefits in the construction of these dams. By 2021, Thailand aims to reduce its reliance on fossil fuels by generating 25% of its electricity from renewable resources. In order to achieve this, it will be using 90% of the energy produced from the Xayaburi Dam and by 2025, the other 11 proposed downstream hydropower plants in the Mekong could potentially meet between 6-8% of South-East Asia's electricity demand. 

With COP21 nearing, there is a huge expectation for nations such as these to move towards renewable energy sources, and in the majority of these countries, due to the high levels of rainfall and steep topography, the most abundant resource is hydropower. 

However, there appears to be a trade off; dams have global and national benefits through the low CO2 emissions and will respond to immediate spikes in energy requirements; however, in many cases, there are also significant ecological and social impacts. It seems that a decision must be made about which environmental impact is less detrimental to the future of our planet.

I must say, I've struggled to form an opinion on hydropower in the Mekong. I am all for clean energy and it is promising that developing countries are meeting their energy demand in a more sustainable way, but I find it hard to ignore the huge impacts that this has on biodiversity, especially with new research stating that we could be entering the sixth mass extinction. Ziv et al's study shows that some of the main-stem dams have lower impact on biodiversity, therefore I am inclined to support the construction of these lower impact dams and would look to meet remaining energy demand with alternative forms of sustainable energy. 

The Hydropower Dilemma

Although widely acknowledged as a renewable energy source, there are many debates about whether hydropower is actually sustainable. 

In my last post, I aimed to outline the historical development and production processes of hydropower, although it was difficult to research this subject without becoming distracted by the controversies that surround it. In this post, I will consider the complexities of this renewable resource to see whether hydropower is truly a sustainable and environmentally beneficial source of energy.

Barra Grande Hydropower Plant, Brazil
Source: Alcoa

Is Hydropower Sustainable?

I'm sure every geographer has had the UN's definition of sustainability drilled into them from a young age. In the Brundtland report it is defined as "meeting the needs of the present without compromising the ability of future generations to meet their own needs". 

Many argue that hydropower is not a sustainable resource as many of its impacts will prevent future generations from meeting their own requirements; displacement of people from their homes, modification of the natural environment and trapping of silt within dams are but a few of the undesirable consequences. Research by Evans et al. (2009), acknowledges these negative impacts but, despite this, hydropower is found to be the most sustainable renewable resource in terms of availability, affordability and efficiency and the second most sustainable resource overall, after wind power.

Another study into hydropower by Yuksel (2010), outlines a number of reasons why hydropower can be considered a sustainable resource. These justifications include: sustaining air quality as it produces no pollutants; potential to limit climate change; a reliable and flexible source of energy; affordable energy for the future due to long life of dams, which function as a source of fresh water, enabling economic and recreational development. 

However, a large amount of research demonstrates that there is not a simple yes or no answer to this question, with location significantly influencing how sustainable a hydropower project is. Evans et al. (2009), outlines the importance of taking location into consideration; the research states that although CO2 emissions are relatively low for manufacturing and operating hydropower plants (of the renewable energy sources, only wind power emits less CO2), the type of terrain flooded by the dam has a heavy impact on CO2 emissions. As a result, there are large variations between plants. The more biomass contained within the proposed hydropower site, the higher emission levels, therefore tropical regions have the highest emissions, but this decreases with age as decay takes place. 

Frey & Linke (2002), also recognise that the sustainability of a reservoir hydropower plant is dependent on the environment in which it is built. Although dam creation can impact migration of fish and cause the loss of terrestrial habitats, it can also provide flood control and water for irrigation; these impacts are case specific with some plants having more adverse affects than others.

Another factor to take into consideration is the type of hydropower plant being commissioned. Ere & Milewski (2002), acknowledge that modification of the natural environment, and alteration of sediment flow, is far smaller when run-of-the-river projects are used. However, the trade off is the reduction in energy generation and inability to rapidly meet unexpected demand.

Jochenstein Run-of-the-River Hydropower Plant, Germany
Source: Verbund

The Impact of Climate Change

Hydropower is a controversial issue for another reason: these dams rely upon the hydrological cycle to create energy, however there is wide acknowledgement throughout the scientific community that hydrology will be affected by anthropogenic climate change. The magnitude and spatial distribution of this impact is unclear - while some areas many benefit from heavier rainfall, others many face periods of prolonged drought. 

California's widely reported current water shortage is a good example of how changes in hydrology can impact a region's energy generation. California is currently facing the biggest drought in recorded history and research by the Pacific Institute found that between October 2011 and October 2014, hydroelectricity decreased by 34,000 GWh. On an average year, 18% of electricity is produced by hydropower, but with the persisting drought this has decreased to less than 12%. With water flow to the turbines steadily reducing, hydropower electricity generation is likely to decrease even further.


To conclude...

I started this post as a keen advocate of hydropower and felt it was one of the key solutions for fossil fuel divestment;  it provides a clean source of energy as well as the reliability required by nations to meet immediate high demand. However, whilst researching the subject for this post, I have changed my opinion. Don't get me wrong, I don't think future sustainable energy plans should eliminate hydropower, but I do think that there needs to be careful consideration before construction and the impacts of hydropower need to be considered on a case by case basis. 

As we have seen, the extent that a hydropower plant meets the needs of today as well as those of the future depends on location. It is therefore critical that hydropower plants are as low impact as possible, which can be achieved through careful assessment of the surrounding ecosystems and selecting the most appropriate size and type of plant for the environment. 

However, the impact of climate change on hydropower must also be considered. The alterations in the hydrological cycle due to global warming are hard to predict and as a result, I don't feel that hydropower can continue to be relied upon as the primary renewable energy source. I still believe hydropower capacity should continue to increase because it is an important part of meeting the global energy demand; however, this responsibility must be shared amongst other sustainable technologies to prevent periods of insufficient supply should climate change severely affect the hydrological cycle in future.

History of Hydropower

Harnessing the power of water isn't a new concept. As early as two thousand years ago, the Ancient Greeks were using water as a source of energy. The earliest utilisation of this energy was to grind flour, but by the mid-1800s a French Engineer, Benoit Fourneyron, had produced a highly efficient turbine; the design was then improved upon and in a short period, numerous factories used this turbine style. By 1800, water power from the Grand Rapids in Michigan was being used to provide electricity to a local theatre and store and two years later, the first hydro-electricity plant opened in Wisconsin.

The world's first Hydro-Electricity Plant at Appleton, Wisconsin
Source: National Geographic

Today, hydropower is the most widely used renewable resource, representing 6.8% of the world's primary energy consumption. In 2013, China, Brazil, the US, Canada, Russia, India and Norway accounted for over 62% of installed global hydropower capacity.  Globally, the largest dam for installed capacity is the Three Gorges Dam spanning the Yangtze River in China and closely followed by the Itaipu Dam bordering Brazil and Paraguay and the Xiluodo Dam, situated on the Jinsha River which was completed in 2014. 

Shares of Top 6 Countries for Global Hydropower Capacity
Source: REN 21

To create hydropower, the kinetic energy of moving water must be utilised. The diagram below shows the movement of water through a Reservoir Hydropower Plant. By opening the gates, gravity forces the water down the Penstock as shown below, which rotates the turbine as it moves through. This turbine is attached to the generator which produces the electricity for transportation via power lines to homes and businesses. 

Reservoir Hydropower Plant
Source: Tennessee Valley Authority

In addition to the Reservoir Hydropower Plant outlined above, there are two other ways in which hydropower is created; Run-of-the-River and the Pumped Storage methods. All three are outlined below:

1. Run-of-the-River 
Run-of-the-River plants generate energy on a smaller scale, usually diverting part of the river and using its natural flow to rotate the turbines before returning it downstream. It is a low-impact way of producing hydropower without the need to create large dams but due to the lack of reservoir, energy is reliant on the flow of water at that time, therefore energy generation cannot suddenly increase to meet demand.

2. Pumped Storage
During periods of high energy demand, water flows from the upper reservoir into the lower reservoir, rotating the turbine as it travels. However, unlike the second example, during periods of low energy demand, the upper reservoir is recharged through pumping water from the lower reservoir. Due to the storage of water, demand can quickly be met by the release of water, despite this, once the upper reservoir has been used, it must be recharged for energy generation to continue; additional energy must be used to complete this action.

3. Reservoir (Storage)
As shown in the diagram above, reservoir hydropower plants require the creation of  a dam to collect the water which can then be released from the gates in order to produce energy. Water is conserved as potential energy within the reservoir which can be converted to electricity as and when there is demand. Nevertheless, there are numerous environmental and social impacts of dam construction including destruction of natural habitats and relocation of towns and villages; I will go into these issue in more detail in my next blog.


Although reservoir hydropower is the most widespread, smaller scale run-of-the-river projects are becoming more common, with proposals set for a number of Himalayan rivers. Overall, global hydropower capacity is increasing and 2014 saw a 2% rise in global output with 19 new hydroelectric plants under construction. Hydropower has even greater potential in future because not only has the technology and infrastructure developed significantly to allow for huge quantities of electricity to be produced, but dams can also meet urgent energy demand, something that is critical for nations intending to replace fossil fuels with renewables. 

I certainly expect hydropower to become more heavily relied upon as nations strive to meet energy demand through sustainable means.

Spotlight on the UK: How green are we?

After focusing my last post on global renewable energy use, I came across a fantastic study by the Carbon Brief which looks at the spatial distribution of energy production in the UK (I will explain in more detail later). I then started thinking about the UK's sustainable energy efforts and thought it would be interesting to see how we rank against other leading green nations.

Earlier this year, the Department of Energy and Climate Change (DECC) released details of the change in the UK's energy production between 2013 and 2014. At first glance, the statistics look promising, with a reduction of 1.5% in total energy generation. Fossil Fuel and Nuclear Power production decreased by 3.6% and 0.7% respectively, with renewable energy increasing by 4.3% in the same period.

UK Electricity Generation, 2014
Source: DECC

These statistics confirmed my opinion that renewable energy is becoming more and more common throughout the UK. From the offshore wind turbines I can see from my grandparents' window on the North Norfolk coast, to the solar farm that has emerged on the side of the A14 as I drive to Cambridge, I have become increasing aware over recent years of the acceptance and spread of renewable technology. So I was shocked to see that the UK's share of electricity generated by renewables in 2014 was only 19.2%, slightly below the global average of 22.8%. 

This got me thinking; who are the global leaders when it comes to renewable energy? 

Many reports mention China as renewable energy leaders, because they are the biggest generator of renewable power- but this can be explained by the sheer size of the country. For this post however, I am not considering them as leaders of clean energy; as a nation they still meet 66% of their energy demand with coal and 24.2% with oil & gas. Instead, I'll be using examples of countries that are meeting the majority of their energy requirements with renewable power. 

Iceland, for example, produces 100% of its electricity (85% of its primary energy) from clean sources. This has been achieved by harnessing the hydropower and geothermal energy available in the region. Other advanced European countries, such as Denmark, Germany and Spain, all generate large amounts of solar and wind power. Looking outside of Europe, two countries that are leading the way in sustainable energy are Paraguay and Costa Rica, both of which produce the majority of their energy from renewable sources. Not only do they both supply their own country's electricity predominately through hydropower, they provide clean energy for other nations as well. For example, the Itaipu Dam on the border of Paraguay and Brazil provided 75% of Paraguay's and 16.9% of Brazil's electricity in 2013.

Another country that I think is certainly worth mentioning here is Norway. Although enough renewable energy is produced to meet 98% of their demands, the majority of this is exported to other nations. Norway certainly cannot be considered a green nation because it is  currently the third-largest producer of gas and seventh-largest producer of oil in the world, but their three biggest sources of energy are still hydropower, wind and geothermal energy.

It is clear that the UK's is not yet reaching these levels, so I am keen to share with you the study that motivated me to take a closer look on the UK's energy production because it gave me a better insight into the resources available to us and the complexities we face.

Spatial Distribution of the UK's Energy Production:

The Carbon Brief recently published research on the geographical distribution of the UK's electricity generation. The results are shown in the diagrams below, giving a visual insight into how different areas can benefit from their different resources.

Geographical Distribution of Hydropower, Wind Power and Solar Power
Source: Carbon Brief 

Geographical Distribution of Nuclear, Oil and Gas

Source: Carbon Brief

The first diagram, shown above, gives a clear picture of renewable energy distribution across the UK. Hydropower is predominately confined to mountainous areas where steep valleys are available for dams, while wind power is widely distributed across the country, located either along coastlines or in areas of high elevation. Solar energy is largely contained within the South of the UK where higher irradiation allows for greater energy production. The second diagram shows the wide distribution of coal and gas, with nuclear plants located in coastal locations with access to large amounts of water for cooling.

To conclude...

Other countries are successfully harnessing the clean resources available to them and as a developed nation with a varied geography, the UK has both the financial and geographical resources to move away from fossil fuel and increase reliance on renewable energy.

However, I can now see the complexities that arise with this transition. In my last post, I concluded that clear strategies are required on a global level in order to increase the reliance on renewable energy, however this research made me realise how important it is to also produce strategies on local/regional levels. 

Using the UK as an example, vast geographical variations exist within a relatively small area, therefore there is a lot to consider when implementing renewable technologies on a national scale.  Even if COP-21 results in legally binding targets, it won't be a straightforward rollout of renewable technologies - whether it is finding the highest areas for new wind turbines, or calculating insolation levels to build new solar farms, it is imperative that variations in regional resources are taken into account to maximise energy production and ensure that we are meeting the UK's energy demands.

Renewable Energy: How far have we come?

In my following blog posts, I intend to go into the detail of renewable technologies themselves. But I felt it was necessary to first gain a better understanding of the current global use of renewable energy in order to see how this compares to the consumption of fossil fuels.

Renewable energy still sits within the shadow of fossil fuels, as shown in the figure below. Of these carbon rich sources, oil is dominant with coal consumption increasing substantially. 

Source: BP Statistical Review of World Energy 2015

Energy requirements are rising, which is predominately being met by fossil fuels. However, a study by Marques et al. (2010), suggests that this growing energy demand actually promotes sustainable energy production because many nations want to become more self-sufficient, leading to increased renewable technology rollout. And global renewable energy use is certainly increasing, from 8.5% o global electricity in 2013, to 9.1% in 2014. The five out commonly used clean resources are: Hydropower Wind Energy, Solar Power, Biomass Fuel and Geothermal Energy. Hydropower accounts for 65% of renewable energy production followed by Wind then Solar Power. Biofuel is the fourth most commonly used, with Geothermal Energy being the least utilised resource.

There has also been a greater investment in renewable energy, with the Office for National Statistics announcing earlier this year that the UK is on track to meet its 2020 EU sustainable energy targets after supplying 15% of its energy in 2013 with renewable resources. In 2014, Denmark revealed its target to become 100% reliant on renewable energy by 2050 and they are well on their way, producing 39.1% of their current energy from clean sources. Leading the way in the US is the state of California, with an ambitious target of providing 33% of its energy from renewable sources by 2020. 

It is apparent that significant progress is being made, however, many are recognising that more still needs to be done. This is demonstrated in a recent study by Remboredo (2015), who suggests that the current disjointed approach to renewables should cease and be replaced by a greater international collaboration. Therefore a combination of international cooperation and legally binding targets are required in order to see more countries adopt objectives similar to Denmark's. 

We could potentially witness this in a few weeks' time at COP-21... Here's hoping.

An Increasing Focus on Renewable Energy?

As COP-21 in Paris draws ever closer, the spotlight is focusing on the world's leading political figures, business leaders and climate scientists. I, for one, am waiting with baited breath for what I feel could potentially be one of the most defining moments in history. 

After the poor result from the Climate Summit in Copenhagen in 2009, this is a crucial moment for not only our political leaders and scientists, but for the 7.1 billion people on this planet. Another summit cannot pass without a legally binding agreement to reduce carbon emissions and mitigate Climate Change. Nations must work together in order to keep the global temperature rise under the 2°C limit; a threshold often cited by scientists and the UNFCCC. 

The impact of anthropogenic activities on climate change has been acknowledged by scientists for decades. In 1972, James Sawyer published research into the link between atmospheric CO2 increases and human activity (Sawyer, 1972). Then in 1988, climatologist James Hansen testified to the United States Senate that climate changes were the result of human induced activities. Today, we have far greater insight, with the IPCC's 5th Assessment Report, stating that 78% of the total CO2 emitted into the atmosphere between 1970-2010 was caused by fossil fuel combustion and industrial processes. As shown in the figure below, of all the greenhouse gases entering the atmosphere, CO2 emitted by anthropogenic sources is by far the greatest and it is rapidly increasing. 



Source: IPCC, 2014: Summary for Policymakers, In: Climate Change 2014, 
Mitigation of Climate Change

Although today it is widely acknowledged that humans are a cause of climate change, the subject has historically been highly contentious with many global leaders refusing to acknowledge the relationship between anthropogenic changes and the Earth's warming. Progress to limit emissions has been slow as a result, but many, myself included, hope that COP-21 will result in a legal agreement that will mitigate climate change and its impacts. 


If the Paris Summit results in some hard targets and limits on greenhouse gas emissions, countries will be forced to look at alternative energy sources and move away from fossil fuels. As a result, I have chosen to write about renewable energy, a subject of immense interest to me, in this blog.

There are numerous energy alternatives, but of course each one has its difficulties, whether it is aesthetics, expense, or unreliability. Over the next few weeks, I will be looking into some of these alternative forms of renewable energy, including numerous well known technologies, as well as some of the lesser known and less widely distributed ones.

Californian wind and solar farm
Source: oag.ca.gov

I am excited to learn about renewable energy in greater depth and hope to challenge my own opinions through delving into this subject and studying conflicting viewpoints.

For anyone reading this, I hope to provide you with some new insight into this innovative, exciting and fast changing area.