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Between Two Sources: Hydropower and Geothermal

Who’s the Beauty and Who’s the Beast? Or is there none at all?

The world is a conundrum of enigmas, always difficult answers to difficult questions. It makes us humans contemplate everything we do, and it’s crucial for us to be careful, even when it comes to renewable energy. As the second article of this three-part series, this will feature the comparison of two different energy sources, hydropower and geothermal energy, in three perspectives, society’s, the economy’s and the environment’s.

For context, hydropower is the basic principle of creating energy from moving water. Potential energy in the water is turned into kinetic energy, and that afterwards goes through a turbine which connects to an electricity generator. Regarding the process, a dam is constructed, and a reservoir is gradually built up. The reservoir will then run through a shoot, moving the turbine, thus producing energy. On the other hand, geothermal energy is created contrastingly. Its source is under the Earth’s surface, not above. Simply, geothermal energy is energy derived from heat within the Earth. In the Earth’s centre, thermal energy is stored in rocks and fluids, therefore, wells (about a mile deep) are drilled into the ground to reach geothermal resources. These resources then power turbines which are linked to electricity generators. It’s easy to see how these two sources contrast.

So how do they contrast in other aspects?

In a societal perspective, hydropower creates “boomtown effects”, a set of socio-cultural impacts collectively. Due to many dams having to be constructed, there will be sudden inflows of construction workers and other related groups. This causes social, cultural and health problems in remote or local areas on a local community scale. For example, the Kenya Third Nairobi Water Supply Project. Many family problems arose in the local area, and it had a major impact on school-going children. Several girls were lured by nearby dam employees to drop out, and many became pregnant. During construction, there were health-related issues too. Sexually-transmitted diseases, such as AIDs, peaked, and there was a considerable effect on girls’ education and health. It was brutal out there. However, there are social benefits too, that are often overlooked in the ongoing international debate on dams. Dams provide irrigation benefits, as well as improved flood control, though it often depends on the location’s topography. Regardless, the societal transformations induced by irrigation are usually hugely advantageous.

Unfortunately, it’s always 1 step forward, and 3 steps back. Though preventing floods prevents damage to homes and human health, floods bring benefits to many places. As an example, Niger rivers. They flow through valleys in which agriculture depends on recurring natural floods, and these annual floods provide necessary nutrients. Thus, most cultivators have modified their agricultural patterns to “absorb” the flood into their agricultural strategies. Moving back to the topic of humanity, the most distinct social liabilities of dams are population displacement. With a sudden increase in population, the magnitude of its consequences is felt everywhere. Sources and production systems start weakening, due to the rising residents, and people start becoming jobless. Healthcare starts deteriorating, many income assets are lost, there is expansion in levels of food insecurity and potential impoverishment, and lots are forced to involuntarily resettle. It’s treacherous.

Hence, what about geothermal energy? Are social impacts happier or even more sour? In its case, it bears similarities to the social impacts of hydropower. Geothermal energy does bring an influx in local populations as well, along with population displacement, migration, loss of existing social infrastructure and financial instability. But it’s different as well. It raises an issue in land rights, the rights of the indigenous and stakeholders. Though perhaps accidental, many power plants sometimes disrupt or displace the private areas of the indigenous, causing cultural and social disputes. Moreover, the visual impacts generated. During drilling and construction, the general aesthetics of the location will be unappealing to many living citizens, and though it’s temporary, it’s notable. This may negatively affect tourism in the area, which will bring many economic disadvantages. Furthermore, speaking of citizens, are they affected by the power plants? Though geothermal energy is cleaner than other resources, it still produces the gas, H₂S, a common gas or waste product found during drilling or in sewers and wastewater. H₂S brings many dangers: it emits another toxic gas, sulphur dioxide and is easily flammable. Not everyone can be happy and healthy.

Déjà vu? Is it as bad as hydropower? Fortunately, no, for there are many simple solutions to its issues. Solutions like limiting the interaction between the workers and the indigenous communities, yet ensuring that both sides can benefit from the energy made, for instance, the indigenous getting access to the provisions created. Also, painting the power plants neutral colours, to minimize the visual impact and boost tourism. Furthermore, there are several social benefits of geothermal energy too. In particular, geothermal power plants pave ways for agriculture or horticultural farming. By way of illustration, the Olkaria I power plant, in Kenya. The power station was constructed near Lake Naivasha, due to its abundant freshwater and suitable climate. Under the station’s implementation, the surrounding Southlake road was opened and this resulted in an increase in agricultural activities, as well as improved access for more. As of now, Kenya’s agriculture has developed so much, it surpassed Israel, and is currently a world leader in horticultural products.

However, is geothermal energy faring as well on the economical side of things? According to, it is. Geothermal power plants not only present opportunities for agriculture, but for tourism as well. A notable example is the Svartsengi geothermal power plant, situated in Iceland. Connected to a popular spa, the Blue Lagoon, the location has attracted more than 75,000 visitors since 2001, a profitable number. Geothermal energy has been beneficial in more direct ways as well. As once quoted by Jennifer A. Oduor, ‘Energy is a means to development’. Referring to her, she writes that geothermal energy, in Kenya, managed to generate a gross revenue of Kshs 1.7 billion from 2004 to 2005, additionally mitigating poverty. Presently, only 15% of Kenyans have access to the country’s installed capacity, and geothermal energy contributes 11% of that total. Luckily, geothermal energy is very affordable and cost-effective. Arcadia writes that a geothermal power plant of about 404 square miles of space can generate 1 gigawatt (1000 megawatts) of electricity every hour, compared to a wind farm, which would consume 1335 square miles of land. The initial cost would be around $2500, in the US, per every installed kilowatt, and to maintain it, costs range from $0.01 - $0.03. From a household perspective, electricity from a geothermal heat source would cost 4.5 to 7.3 cents per kilowatt hour. Bonus point, geothermal energy is incredibly versatile too. It only needs relatively little land, no damming or harvesting required and is able to share land with cattle and wildlife.

On the other hand, hydropower is performing just as well economically. According to the National Hydropower Association, the resource offers the lowest levelized cost among all sources. Conventionally, each installed kilowatt costs $1000 - $5000, and in the US, it costs $0.05 every kilowatt per hour. To illustrate its low costs, the USACE hydropower program is a fine example. 75 of USACE plants were able to generate over 72 billion kWh annually, enough to charge ten million households or ten cities. In addition, the average repayments in the US were estimated to be at $1.23 billion per year, from 2010 to 2016. From low operating costs (hydropower plants don’t run on fuel) to ample supply to inexpensive consumer prices, hydropower is doing better than it ever was.

Despite hydropower being cheaper than geothermal energy and varying in profits, both generate similar advantages. For example, geothermal energy can create jobs in manufacturing and construction, with 3.3 jobs per megawatt installed. The same applies to hydropower, the US hydropower industry currently employs up to 300,000 people, to run their facilities, construct, develop projects and for maintenance. Other advantages include wider access to essential services and a rise in trade or business. But nothing’s forever, nothing is as good as it seems. As far as disadvantages go, these resources offer opportunities for political conflicts, especially hydropower. To give an example, the Renaissance Dam project, located on the Nile River. The project initiated a dispute between ‘Ethiopia’s developmental needs and water scarcity concerns in Egypt’. Though climate change does have a hand in this problem, national borders and meagre resources are primary drivers too. Discussions between the two parties have been so unprogressive, that countries, such as the US, have been called in to conciliate. The dispute remains ongoing. Regardless, things are looking bright for hydropower and geothermal on the economical horizon. There have been no burning red flags yet.

Now the aspect everyone probably came for… the word that sprung into one’s mind when they hear ‘renewable energy’: environmental.

In the case of hydropower, the resource causes significant reduction in smog, acid rain and pollution. This is because hydropower runs mainly on water and due to this, doesn’t emit any waste heat or gases, making it a clean source. Also, hydropower dams help to control any wide fluctuations in water flow, if there is any. During dry months, they increase water flow, replenishing aquatic habitats. On the contrary, they reduce water flow too, which prevents heavy run-offs damaging plants or vegetation near stream banks. Speaking about vegetation, hydropower benefits agriculture as well. Hydropower facilities are able to store vast amounts of water, which can help farmers or irrigation systems, if there is a lack of rainfall. Not only does this boost agriculture, it reduces wastewater as well as decreases any chances of flooding or drought, for it protects the underground water table from exhausting. As a matter of fact, 10% of the cropland in the US uses irrigation that comes from the stored water behind hydropower dams.

Conversely to these advantages, hydropower provides some consequences too. Points include the natural change of water flow. For example, oxygen levels below dams, in the southeastern states, get so low that aquatic life is often severely affected. Furthermore, the disruption can potentially degrade the water’s quality, because it doesn’t allow critical nutrients or sediment to pass through, and the construction of a dam can destroy marine habitats as well. In addition, a reservoir widens a lake, slowing the movement of water and increasing its temperature. Despite all the opportunities it may provide, these changes can be detrimental to marine life. For instance, 11 dams on the Mekong mainstream are predicted to lead to 880,000 tons of fish directly lost by 2030. The damage to wildlife leads to many more problems as well. Although hydropower doesn’t emit any gases, the manufacturing process does. However, once that’s over, the facilities remain clean. Sounds positive, right? Yes… till any marine life passes away. The rotting of any dead organic material not only pollutes the water, but forces facilities to emit vast amounts of gases such as carbon dioxide and methane, to return the dam to its old state.

Therefore, is geothermal energy a better option? Environmentally, geothermal energy is striving quite well. It doesn’t produce any waste, and also doesn’t require any transportation facility, which helps lessen carbon emissions. Additionally, like hydropower, geothermal power plants emit extremely less amounts of carbon and sulphur dioxide, and no amount of nitrogen oxide at all, but unlike hydropower, the levels remain low even during production. Even better, the gases emitted are not from combustion, but natural components of a geothermal reservoir. According to an IGA (International Geothermal Association) survey, geothermal only emits a weighted average of 122 g/kWh, compared to other fossil fuels, like coal, which is way higher.

Unlike both fossil fuels and hydropower again, geothermal energy creates very minimal land or water pollution. Geothermal uses cooling mechanisms to emit heat into the atmosphere, instead of water bodies, which is a greener alternative. Even so, geothermal fluids sometimes contain useful by-products, like salts and silica solids, which can be helpful for industrial use, or harmful if not in the reservoir. Nevertheless, geothermal plants solve those issues by re-injecting the dissolved minerals back in and recycling any wastewater, to renew the reservoir.

On the topic of wastewater, even though geothermal energy recycles their wastewater, not all of it is clean. The main geothermal wastewater produced is brine. It’s not toxic, however, it can be a risk to health, depending on its fluid chemistry. Also, if the substance possibly contains any heavy metals, such as mercury, lead or lithium, it poses risks to water pollution. To add fuel to the fire, if any brine is leaked or above surface, it can cause high metal concentration in soils, which severely affects vegetation. Geothermal power plants pose more risks as well, because if there is excessive fluid withdrawal, it may cause land subsidence, resulting in cracks in the ground or in rocks along with instability in pipelines, drains and even buildings. Unfortunately, similar to hydropower, geothermal plants emit a toxic gas, hydrogen sulphide (H₂S), during drilling or vehicular movement. Hydrogen sulphide releases a rotten egg-like smell in the atmosphere, and if there is high concentration, can affect humans, by causing nausea, skin irritation and respiratory failure.

So are hydropower and geothermal as clean as the general public perceives them to be?

Yes or no, it’s important to note that both resources are better choices than fossil fuels. Despite the stigma of renewable resources not living up to the potential of their harmful predecessors, countless research studies have shown that renewable resources generate as much energy as coal or gasoline, occasionally even more. As stated by a report by Carbon Tracker, renewable sources can potentially produce thousands of petawatt hours (PWh) of electricity every year, while currently, the world’s electricity demand stands at 27 PWh.

SDG Goal No. 7 is Affordable and Clean Energy, and renewable energy, including hydropower and geothermal energy, seems to be a great way of achieving that goal. Statistically, progress looks good, with the number of people with access to electricity going from 78 to 87%, and the amount that doesn't, dropping down to lower than one billion, between 2000 and 2016. Hydropower and geothermal energy seems to be a huge help, especially with hydropower being responsible for 16% of the produced electricity worldwide, posing undeveloped potential. However, referring to the SDGs 2020 report, due to the pandemic and stalling, progress has been deteriorating, and the world is not on track to achieve all the goals by 2030.

To conclude on this article, it’s important to stress one point. It’s essential that all comprehensive analysis on renewable resources be taken into account, all its advantages and disadvantages. Biased methodologies can lead to instability in projects and politics, thus, correcting those should be a priority, for the good of our society, economy and environment. At this point of time, everything has changed and we know the consequences of climate change all too well, since it has worsened over the past 10 or 22 or 100 years. With the height that climate change has reached, it’s crucial to think carefully about our choices. It’s bittersweet to think about the damage that we do, but although it’s nothing new, it doesn’t mean we can’t begin again.


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