Icarus’ Legacy — Episode 3 — Hydropower and Geothermal Energy
(Google Doc version more suitable for PC and Tablet is here)
In episode 2
Produce, consume, pollute, repeat
Energy consumption has been growing at an incredible rate, mostly supported by fossil fuels, and with it the greenhouse gas emissions have piled up in the atmosphere, starting to change our climate, for the worse, and polluting our environment. Energy production WILL continue to grow over the next 30 years, to support the world population growth, and also importantly to lift billions of people from poverty, especially in Africa and Asia.
We need to reduce net emissions down to zero if we want to have a chance to limit the effects of climate change, and make the air of our cities breathable again. To do this, we need a radical transformation of the energy sector, moving to clean and renewable sources.
The introduction of renewable sources and the use of electricity to heat buildings, fuel electric vehicles and part of industrial processes can displace a large part of the fossil fuels, and it can be done with the current technologies.
Electricity from solar plants and wind farms is now cheaper than fossil fuels generated power, so that’s where we will see most of the practical change over the next few years, as many new plants start to generate clean electricity.
While we do this, research must focus on the next big hurdles, to also resolve the problems of heavy transportation (ships, planes, lorries) and the industrial products that require high temperature processes (like cement, steel, petrochemical products, to name a few). Green hydrogen, that can be obtained from electrolysis, is a promising technology in these sectors, but we will require a number of breakthroughs before we can produce it cheaply enough so it can be adopted on a global scale.
The full second episode is here
In this episode
We are running out of space in our game of Tetris — we need to slow down emissions. We start to look at the history and perspectives of clean and renewable sources, starting from hydroelectric and geothermal energy, which were already used over 100 years ago, and will continue to have a role in the transformation of the energy sector.
A totally new level
Our Tetris screen has been filling up quickly, and the emission pieces are coming in at alarming speed. We have limited time to take action, or it will be game over.
If we want to limit global warming to 1.5 or 2 degrees Celsius above pre-industrial levels, we have a budget of around 400–800 Gt of CO2, which is 10–20 years of emissions at the current rate.
CO2 concentration in the atmosphere has been stable from 1850 to 1950 (increased from 285 to 300 ppm) when it started to grow steadily. It passed 400 ppm in 2015 and it is now at 415 ppm.
Up until the 90s it was primarily Europe and North America to account for most of the emissions, but these regions have now peaked and are reducing their impact. Massive increases in industrial production and population now see Asia as the top greenhouse gas emitter.
But China has recently committed to zero their emissions by 2060 — this was the best news against climate change and pollution of 2020!
But when will those pieces start to slow down? We must clear up our screen and environment by reducing net emissions down to zero.
To do this, we need a radical transformation of the energy sector, moving to clean and renewable sources. Most countries are committed to it and, thanks to new technologies, some are showing that winning is possible.
We’ve come a long paved road
History and Perspectives of Clean Sources and Technologies
In the beginning it was all traditional biomass, wood and possibly animal and agriculture waste to fuel our limited energy needs
By the time a new renewable energy source, hydroelectric, appeared as a viable way to generate electricity, in the late 19th century, the world was already burning crazy amounts of coal, the most accessible, with the limited technology of the time, of fossil fuels. Coal fired steam engines were dominating industrial landscapes, railways and oceans.
In the 1930s it was the time for oil to take centre stage, especially for the growing road transportation sector. In the 1950s natural gas usage started to scale up, hearing our homes and our food. Fossil fuels usage kept on growing, first supporting the development of the western world, and then, since the 1990s, fuelling Asian countries like China and India and their booming economies and populations.
The growth of hydroelectric, the introduction of geothermal energy and the deployment of nuclear energy at scale, in the 1970s, only made a tiny dent in the energy mix, as the world economies continued to expand by digging out and burning fossil fuels.
Only over the past ten years, thanks to technological progress and mass scale production, renewable sources like solar, wind and modern biomass have shown true potential to displace fossil fuels: they are widely available, non-polluting and, finally, very cheap.
It’s still only a promise: in the same decade, the growth in fossil fuel energy production has been much larger than the total production from modern clean and renewable sources (hydro, solar, wind, biomass and nuclear).
This is changing now — the projected growth in new energy capacity is mostly about renewable sources. Plans for new fossil fuels plants are drying up, old coal power plants are shutting down, gas power plants spend more and more time on standby, and we can finally see this long expected change of direction.
Hydropower
Humans have used water to power mechanical processes for thousands of years, through water mills with increasingly more complex and efficient designs.
The first example of electricity generation through hydropower was created in England in 1878, but the first application at scale was built in the US, in Niagara, just three years later. A rapid development followed, and by 1890 there were more than 200 power stations in North America alone.
Water was first diverted from the Canadian side of the Niagara River for generating electricity in 1893. A small 2.2 MW plant was built just above the Horseshoe Falls to power an electric railway between the communities of Queenston and Chippawa.
Today the churning river provides the driving force for almost 2 GW of POWER from a number of power plants on the Canadian side. The three largest are Sir Adam Beck Niagara Generating Station Nos. 1 and 2 and the nearby pumping-generating station.
For over 60 years hydropower was the main source of electricity production around the world. Coal first, and natural gas later, overtook hydro in electricity production, and today fossil fuels produce more than 4 times the electricity we obtain from hydropower.
The development of new hydropower plants was slower than new fossil fuel power generation, but continued steadily, and larger, more powerful plants were built all over the world, often using massive dams and reservoirs spanning square kilometres.
The generation of electricity from hydropower has quadrupled since 1970 and doubled since 1990. Hydropower is still the main low-carbon source of electricity, accounting for 17% of global electricity production (compared to 2.6% and 5.3% respectively for solar and wind energy, and 10.4% for nuclear). Fossil fuels, in comparison, account for 36.4% and 23.3% of electricity generation, respectively for coal and natural gas. While hydropower will remain important in the energy mix, especially because of its low production costs, its development is predicted to slow, as the most favourable water flows have mostly been utilized, and because many countries cannot count on this type of energy, lacking major waterways.
Hydropower is viable also on the smaller scale, without dams and reservoirs, which is considered a more environmentally-friendly option, as it does not interfere with river flows and it does not displace communities or ecosystems. In this way, smaller water flows can address the requirements of local communities through small and micro hydro plants.
As with every decentralized production of energy (like residential solar panels, heat distributed from processing plants or local geothermal stations), it reduces the load and the required investments on power grids, and it increases their resilience.
Pumped Storage
Some hydro plants go well beyond the use of naturally occurring water flows, and operate as a massive energy storage. This is done by creating a high altitude and a low altitude reservoir, generating electricity when the water is allowed to flow from high to low, and consuming electricity when the water is pumped back to the high reservoir. These systems take advantage of the differential price of energy between peak times, when they generate, and low-demand times, when cheap or free energy is used to pump the water back up. The larger the reservoirs and the drop in altitude between them, the larger the energy store.
Another important measure is their ability to quickly discharge water from high to low altitude through turbines, which determines the power of the plant.
As an example, excess production from renewable sources or from nuclear plants could be used to refill high reservoirs. Even with no cost differential, or at a marginally higher cost due to loss of energy and water evaporation, pumped storage constitutes an essential element of the energy grid, for its ability to compensate the intermittent nature of solar and wind sources. This reduces waste and provides near-real-time and on-demand activation, a flexibility which is not available with any other type of plant.
As for normal hydroelectric plants, this type of solution is limited to regions that have the right climate and geophysical conditions: plenty of water, easy to construct reservoirs from existing natural environments, and substantial elevation drop between reservoirs. So in practice this is only possible in mountain regions that benefit from natural water flows.
However, you don’t need a major water flow to build a pumped storage plant, as the water is cycled between the two reservoirs, its use is limited to the effect of evaporation. So in practice pumped storage works effectively on minor waterways. This makes this type of solution open to much larger expansion over the next few years.
Hydropower has a global installed base of 1,308 GW, including 158 GW of pumped storage (2019 figures). China, Brazil and the USA are the 3 leading countries, with installed power of 356, 109 and 103 GW respectively. Canada, Russia, India, Turkey, Norway, Japan, Italy, France and Spain are also notable examples with an installed power of over 20 GW each, and hydropower currently being their top renewable energy source.
Geothermal Energy
Geothermal energy uses the heat from within the sub-surface of the earth. In its more generic interpretation, it is available everywhere, and can be used to heat or cool buildings.
This can be done thanks to underground heat pumps, heat exchangers and boreholes which reach depths from a few meters to more than 100 meters, where the temperature is pretty constant and unaffected by the weather. In this way with minimal electricity input, we can obtain a multiplier effect, and reduce energy consumption and emissions.
However, for geothermal energy to generate electricity, we require much higher temperatures (180’C or more) which can only be reached at much larger depths, or in tectonically active regions. At these temperatures, we can generate steam and drive turbines, as combustion power plants do, with the difference that no toxic emissions are generated.
The USA are the largest producer of geothermal power in the world, but countries like Indonesia, Turkey, the Philippines, New Zealand and Iceland are investing heavily in this sector. Global installed power in 2019 stood at 15.4 GW, and 2019 had seen the largest installed growth for over 20 years, to signal renewed interest and a contributing role in producing clean energy.
Iceland is an interesting case as it is generating 65% of its primary energy requirements from geothermal sources, thanks to the many hot springs disseminated in its highly volcanic territory. Geothermal energy is used to produce over 30% of the country’s electricity, but importantly it is also used to generate heat for buildings and industrial processes.
Geothermal energy is a small contributor to the global energy mix, but it is receiving renewed interest because of its clean, widespread, virtually unlimited and reliable all-season, all-latitudes, nature, and its relatively low production costs and impact on the environment.
Compared to other renewable sources like solar, wind or biofuels, geothermal energy only requires limited land use (energy density in MW/km2) can produce energy at pretty much constant and reliable rate, and it doesn’t pollute the environment. But it will require innovation to become more broadly available and at lower price points.
A future evolution includes leveraging “medium” temperatures to produce electricity, thanks to the development of new “binary cycle” technologies — this will make it cheaper and available in many more locations and with less deep boreholes. In many cases it is already possible to use existing sites from dismantled or spent oil or gas extraction wells, as well as drilling technologies used for these fossil fuels.
On the other end of the spectrum, it has been established that drilling at a depth of around 3,000 meters could provide the ability to scale up production, thanks to “supercritical fluids” which stand in a state which is neither liquid nor gas and boast a very powerful energy content. Technologies are close to a breakthrough, where these depths could be drilled safely, and in particular without causing seismic activities. This was the subject of a recent European project, named DESCRAMBLE, which tested a borehole at the Larderello site in Italy, while monitoring seismic impact and using new drilling technologies. They had to stop about 100 meters short of the 3000 meters target, due to high temperatures (over 500'C) but the progress and feedback was very encouraging.
Hydropower and Geothermal energy have played and will continue to play an important role in decarbonising the energy sector, but the near future of renewable electricity generation will primarily rely on the growth of solar and wind sources, given their widespread availability and reducing costs. These are predicted to grow to be individually larger than hydropower by 2030–2035.
In the next episode we will look at solar, wind and modern biofuels: the renewable sources of energy that have seen the largest deployment and drop in installation prices over the past decade.
