The Wonderful World of Waterpower

By Bea Nield

In our ever-changing world, there is a recent and urgent push towards renewable and sustainable energies. People want us to rely less on fossil fuels and make better use of less polluting alternatives. One such source of power is water! In our current world, it’s already utilised in many methods of electricity generation, although these often come with heavy caveats – such as reduced efficiency and a requirement of the local resource. In contrast, substances like natural gas can be pumped internationally with little effect on their viability as energy sources.

Using water as a form of power involves harnessing the energy stored in it to generate electricity or perform mechanical work. A well-known method of this is hydro or hydroelectric power, which makes use of the transfer of energy between GPE (gravitational potential energy) and KE (kinetic energy) stores. It’s well-established in many places and is done by building dams across rivers to create reservoirs and controlling the flow of water through turbines in the dam walls. As the water flows through the turbines, it drives generators to produce electricity. The upper reservoir can even be used as a sort of battery when excess electricity (a concept due to the need for power grid balance) is utilised to pump water up during periods of low demand. Small-scale hydropower systems can even be installed in streams to generate electricity for local communities or remote areas, which typically have a lower environmental impact compared to large dams.

However, there are some environmental considerations associated with the use of water in electricity generation, particularly in large-scale dam projects. Habitat disruption and alteration of river ecosystems can be an issue in the local area. It can also be very difficult for people, particularly those living downstream of a new dam construction, to adapt their ways of life to suit the build, and agriculture can take a particularly heavy hit. Some towns have even been completely flooded to make way for a reservoir, obviously causing a drastic change to the lives of local people.

Although hydropower dams are unviable in the sea, there are many other projects that make use of this vast water-based energy source. Wave energy converters capture the energy from ocean waves and convert it into electricity by various designs, such as oscillating water columns and point absorbers. These typically harness the natural movements of the water throughout the sea, and particularly at its chaotic surface, although underwater currents and the movement of their molecules are also utilised. Meanwhile, ocean thermal energy converters exploit the temperature difference between the warm surface water and cold deep water in the ocean to generate electricity. Similar concepts are used in other sustainable electricity generators, such as those using thermoelectric materials (highly recommend researching them!) to reabsorb excess heat given off by machinery and appliances. Heat exchangers and turbines are used in the process of ocean thermal energy conversion.

It’s not only the main body of the ocean that’s used in electricity generation, but even the tides themselves are great sources of energy. Tidal stream systems use the KE of moving water caused by the tides to turn underwater turbines, generating electricity. Tidal range systems take advantage of the difference in water levels between high and low tides; they, much like many of the other methods at their simplest core, use the flow of water through sluices and turbines to generate electricity.

Fundamentally, the majority of methods use turbines (or water wheels), meaning that most water powered electricity generation is limited by this mechanism and its own limitations. Alternative methods, such as WECs and OTECs utilise differing technologies, and it is this kind of innovation that will hopefully drive our move away from fossil fuels and towards more unique techniques, like waterpower! Water can also be used to transmit power, not just to harness it, as seen in hydraulic systems where it is used to transmit mechanical power, especially in heavy machinery and industrial applications.

The hydrolysis of water using solar power as an energy source, often referred to as solar water splitting or solar hydrogen production, is an upcoming technology for sustainable energy production and storage. Solar power is a clean (does not produce harmful emissions) and renewable energy source that is abundant and environmentally friendly. The production of solar panels can be environmentally harmful, but its use over its lifespan typically evens this out. Building the infrastructure for large-scale solar hydrogen production and distribution requires significant investments, particularly into developing efficient and durable materials and catalysts for the electrolysis process. This research, however, is ongoing and will, hopefully, be more commercially viable in the future. Using solar energy for water splitting eliminates the need for fossil fuels and produces zero greenhouse gas emissions during the hydrogen production process.

This methodology works well to store excess energy because excess electricity generated during sunny periods can be used to produce hydrogen which is then stored and used as an energy source later on, acting in replacement of traditional batteries. It is this nature that makes this method so important, as one of the main issues with solar power is that it is intermittent (viable only during daylight hours and subject to weather), so effective energy storage is vital for this to be a reliable energy supply.

Hydrogen can serve as a versatile fuel and can be used in fuel cells to generate electricity or as a clean fuel for transportation, heating and industrial processes. Hydrolysis using solar power is also a method of electricity generation that is not too affected by geographical location. Of course, areas with large amounts of water and lots of sun will work best, but much of the globe has access to these resources. Water is much more evenly distributed globally than fuels like natural gas and crude oil, although the technology for hydrolysis is not currently commercially popular.

Hydrolysis can also contribute to grid stabilisation, making the transition away from fossil fuels smoother (as many current sustainable energy sources are too volatile and unreliable to use to balance the grid). Hydrogen can be injected into natural gas pipelines, used in power plants, or employed in various energy applications to provide a reliable and dispatch-able source of energy.

Unlike most sustainable sources of energy generation, solar water splitting systems have high efficiency potential (in dramatic contrast to those such as thermoelectric materials, with an estimated potential efficiency as low as 25% in some models). Ongoing research is focused on improving the efficiency of hydrolysis systems, making it more practical for large-scale applications.

Some even imagine a future hydrogen economy, where hydrogen, particularly that produced from sustainable methods, plays a large part of meeting the demands of our ever-growing energy market.

Although this development is continuous, and is projected to be successful, current hydrolysis technologies, especially those using solar power, have relatively lower efficiency and higher costs than current alternative energy storage methods. Even as hydrolysis develops, so to do traditional batteries and competing technologies. Without tackling this problem, hydrolysis will ultimately not be an economically likely contributor to tackling over-reliance on fossil fuels.

In conclusion, the hydrolysis of water using solar power as an energy source has significant potential for clean energy production and storage, but it faces challenges related to efficiency, cost and infrastructure. Continued development in this technology is crucial for realising its full potential and integrating it into our future energy systems.

In sum, the use of water as a source of power is considered a renewable and clean energy source as it produces minimal greenhouse has emissions and relies on a naturally occurring resource.

Therefore, the development of more sustainable and environmentally friendly technologies for harnessing water’s power continues to be a focus of research and development in the energy sector.