Which renewable energy types require water?

Learn about how water is found on Earth….

Renewable energy

The main types of renewables:

  1. Hydropower
  2. Geothermal
  3. Wind
  4. Solar

 

Hydropower

Hydropower is a renewable energy technology that harnesses the power of flowing water to generate electricity. It has been used for centuries and remains a major source of clean energy today.

The earliest evidence of water being used as a source of power comes from mid-4th century water wheel, specifically a horizontal, propeller-like contraption that was used to turn millstones for grinding flour.

Hydro dams

Hydropower became an electricity source in the late 19th century, a few decades after engineer James Francis developed the first modern water turbine. In 1882, the world’s first hydroelectric power plant began operating in the United States.

 

Over time as technological advancements have been made the scale of which hydro dams can produce energy has grown exceptionally. Large-scale hydropower plants typically involve the construction of dams and reservoirs, where water is collected and stored. When released, the force of the flowing water drives turbines, connected to electricity generators, producing clean and reliable power.

Hydro dams’ advantages and disadvantages

Hydropower offers numerous advantages, such as its ability to provide a steady and predictable electricity supply, making it an essential contributor to the global energy mix. However, the construction of large dams can have significant environmental and social impacts, affecting river ecosystems and communities living near the dams. Therefore, striking a balance between harnessing hydropower and safeguarding the environment is crucial.

A specific example of this is the Three Gorges Dam in China. It is an engineering marvel as it is the largest hydro dams in the world and captures the power of the mighty Yangtze River. However, the construction meant disaster for around 4 million people as the dammed Yangtze flooded 13 cities, 140 towns, and 1,352 villages.

Pumped storage

However, there is a secondary form of hydropower that is also used – pumped storage. Pumped storage hydropower is a type of energy storage that uses water to store electricity. It works like a giant battery, storing energy during times of low demand and releasing it back to the grid during times of high demand.

It works by using peaks and dips in the electricity grid to store energy and then to generate electricity. A main advantage of this energy source is that it is the only form of renewable energy that can be turned on and off when demand requires it.

Storing energy: When there is excess electricity available, such as from solar or wind power during off-peak hours, it is used to pump water from a lower reservoir to a higher reservoir.

Generating electricity: When there is a high demand for electricity, the water from the upper reservoir is released back down to the lower reservoir, passing through turbines that generate electricity.

Pumped storage advantages and disadvantages

There are numerous advantages to pumped storage. A key feature that makes it superior to other forms of renewable energy is that the time of when the energy is produced can be controlled. Whereas as other forms of renewable energy are dependent on certain environmental conditions, e.g. solar only works during the day and even then, only in certain conditions. As long as there is water in the upper reservoir, pumped storage can be utilised at any time. However, the disadvantage of this is that the system needs to be ‘recharged’, this is where the water that has been released to the bottom reservoir is pumped back to the upper reservoir. While this does require energy, this can be scheduled to take place when there is a surplus of electricity – e.g. solar during the day.

An additional variable regarding pumped storage is the long term and short-term costings. To initially create a pumped storage system, it is one of the most expensive forms of renewables, however once the system it is running, the system is very cost effective. The operating costs are low and pumped storage has one of the longest services lives compared to other renewables.

Finally, there is one other disadvantage that affects pumped storage. The reservoirs that are essential to the system can be affected by climate change – specifically droughts. If the reservoirs have too little water, or completely dry up, then the system cannot work.

Geothermal Energy

Geothermal energy has the potential to provide an abundant and renewable source of power. This energy is generated by residual heat from the planet’s formation and through radioactive decay within the Earth’s core. Different applications of this energy source include generating electricity, heating buildings, and even growing crops in greenhouses.

There are several ways to capture geothermal energy, which depends on the temperature and accessibility of hot rock or fluids beneath the Earth’s surface:

  • High-temperature reservoirs: In areas with hot rocks or magma close to the surface, drilling wells deep into the Earth is necessary. The extracted steam or hot water is then utilized to power turbines that are connected to electricity generators.
  • Mid-temperature reservoirs: Warmer water found at shallower depths can be used to heat buildings directly or generate electricity through low-pressure turbines.
  • Enhanced geothermal systems: In areas with less accessible heat sources, water is pumped down into the Earth to crack hot rock formations. The heated water then rises back to the surface and is used for generating electricity or heating.

Water plays a crucial role in many practical applications of geothermal energy. Here are some ways water can be involved:

High-temperature geothermal plants:

Direct use: Hot water drawn directly from geothermal reservoirs can be used to heat buildings or industrial processes without utilizing turbines. This eliminates the need for water in electricity generation but still relies on it for heat transfer.

Flash steam

High-pressure hot water reaching the surface can turn into steam, which drives turbines for electricity generation. In this case, the separated water may be reinjected underground or used for other purposes like heating.

Mid-temperature geothermal plants

District heating: Warmer water extracted at shallower depths is often used for heating buildings directly in districts or communities. This system relies on circulating water through pipes to transfer heat to buildings, making water an essential component.

Enhanced geothermal systems (EGS)

Fracturing and reinjection: In areas with less accessible heat sources, water is pumped at high pressure deep underground to fracture hot rock formations and create heat-permeable pathways. This water remains trapped in the fractured rock and does not return to the surface, but its initial use is crucial for unlocking the geothermal potential.

Geothermal energy used for electricity generation often relies on closed-loop water systems, reducing overall water consumption. Although water usage in applications like district heating and industrial processes can be significant, these applications still offer cleaner alternatives compared to fossil fuel-based heating. The EGS technology relies on a one-time water injection for fracturing, but further advancements aim to minimize or even eliminate water use in this process.

Wind Energy – Water in Manufacturing and Maintenance:

 

Wind power is a renewable energy source that captures the kinetic energy of the wind and converts it into electricity. It’s been used for centuries in simple forms like windmills, but today, towering wind turbines dot landscapes around the world, generating clean and sustainable power.

 

Water is not an essential part of wind energy as wind turbines function solely by harnessing the kinetic energy of the wind to spin their blades and drive generators. However, there are indirect ways in which water might be involved with wind power:

  • Cooling: Some wind turbines, especially larger ones, utilize water for cooling purposes. This water circulates through the generator and transformer to regulate their temperature, preventing overheating and ensuring efficient operation. However, these systems are often closed loop and use minimal amounts of water, sometimes even employing treated wastewater or rainwater instead of freshwater.
  • Blade cleaning: While rain naturally washes wind turbine blades, some locations might require occasional manual cleaning, particularly in dusty or polluted environments. In these cases, water is typically used for washing, though the amount needed is relatively small compared to other water-intensive industries.
  • Site construction and maintenance: Building and maintaining wind farms, like any infrastructure project, might involve water for activities like dust suppression, road construction, and equipment cleaning. However, the water usage during these phases is temporary and can be minimized through responsible practices.

Solar Energy – Water for Cleaning and Cooling

 

Solar power is a renewable energy source that captures the energy of sunlight and converts it into electricity. It’s a clean, sustainable, and increasingly popular way to generate power for homes, businesses, and even entire cities.

Solar power itself does not directly require water for its core operation of generating electricity. It harnesses the sun’s light energy to create an electric current, a process independent of water usage.

However, there are a few indirect ways water might be involved with solar power:

  • Panel Cleaning: While rain naturally cleans dust and residue from solar panels, some locations in arid regions or with heavy pollution might require occasional manual cleaning. In these cases, water is typically used for washing, but the amount needed is relatively small compared to other water-intensive industries.
  • Manufacturing and Installation: Building and installing solar panels, like any infrastructure project, might involve water for activities like dust suppression, road construction, and equipment cleaning. However, the water usage during these phases is temporary and can be minimized through responsible practices.
  • Cooling systems: In specific high-intensity situations like large solar farms in extremely hot environments, some systems might implement water-based cooling for certain components like inverters to regulate their temperature and ensure efficient operation. However, such systems are often closed loop, using minimal and often recycled water, not impacting overall water consumption significantly.

Conclusion

As we transition towards a sustainable future, understanding the interplay between water and renewable energy is crucial. Technological advancements offer promising solutions to minimize water usage and maximize efficiency. Closed-loop systems, water recycling initiatives, and innovative cooling techniques are paving the way for a future where clean energy and responsible water management go hand in hand.

By embracing this vital partnership, we can harness the power of renewable resources while safeguarding our precious water resources, ensuring a cleaner and brighter future for generations to come.