Oceans offer an immense source of renewable energy that is generated naturally and predictable, providing a consistent source of electricity generation.
But the equipment used to generate this energy must be continuously maintained in order to withstand rugged ocean conditions and corrosion from salty sea water. There are various designs for harnessing energy from waves, tides, or ocean currents.
Oscillating bodies
The world’s oceans contain immense energy reserves that are only just beginning to be harnessed. Wave power technology uses ocean swells as energy-harvesting sources while tidal power harnesses it from tide movements. Although neither technology is commercially viable yet, they could provide sustainable sources of electricity in the future. Unfortunately however, developing these technologies presents significant obstacles; research, construction and operation costs may be prohibitively high while they could also be vulnerable to weather effects.
Marine Renewable Energy (MRE) represents an enormous global potential, capable of replacing fossil fuels. MRE includes both mechanical energy stored in waves and tides as well as thermal energy from solar radiation and natural phenomena; its total energy capacity has been estimated as over twice that of electricity production globally each day! Each day alone the ocean absorbs enough energy equal to 250 billion barrels of oil.
Optimizing energy systems according to their hydrodynamic resources is one of the greatest challenges in ocean MRE development, and involves an intricate interplay of physical, environmental, engineering, and economic considerations that cannot be assumed at system design stage. This is especially true when dealing with systems reliant upon fluid dynamics for resources like tidal power.
There are various kinds of wave energy converters. Some utilize pistons to generate pressure that drives a hydraulic turbine and produce electricity; others utilize oscillating bodies that track waves to create continuous power; yet a newer type uses a float attached to the seabed that moves in response to waves – an extremely efficient option capable of producing longer term electricity generation than its counterparts.
Tidal power offers an alternative energy solution without dam construction, offering predictability as an excellent renewable resource. Tidal energy production also reduces pollution; numerous projects for tidal energy generation exist across the world today. It remains relatively early days for this technology.
Overtopping devices
Ocean waves provide a renewable, clean source of power that is easily captured. Capturing them requires various technologies from point absorber buoys to fully floating devices that harness this source of energy, using either its kinetic energy to power generators, or its thermal energy through heat exchange. Such systems have become increasingly popular because they offer clean and sustainable alternatives to fossil fuels.
Overtopping devices are long structures designed to use wave action to fill a reservoir to a higher level than its surrounding sea. This difference in pressure forces water through low head turbines connected to electric generators to produce electricity; such devices can either be situated onshore or offshore and cause issues like marine organism entrapment in reservoirs, collision with slow-moving turbines, electromagnetic fields etc.
Structure has an impactful influence on device performance and should be tailored accordingly. Slopes leading to the reservoir must be optimized so as to avoid breaking and achieve an efficient power capture ratio, and other factors like ramp crest level and dimensions also play a part in its effectiveness.
However, their power output often fluctuates significantly and makes connecting to the grid challenging. To address this challenge, researchers are developing new ways of improving these devices’ design and efficiency – for instance a pre-tension cylinder, composite buoy and UMACK anchor are among their innovations which could reduce electricity production costs as well as making them more environmentally-friendly.
Bulge wave technology is another method for tapping ocean energy, employing a rubber tube filled with water that is attached to the seabed and filled with waves that create pressure fluctuations along its length, leading to pressure variations along its length and creating pressure fluctuations that cause pressure variations along its length, creating pressure fluctuations within it and eventually creating bulges with each wave that passes, driving standard low-head turbines while returning the water back into the sea.
Tidal barrages
Tidal barrages resemble dams built across tidal rivers, bays, or estuaries to form a tidal basin and contain turbines to generate power from kinetic energy of inward- and outgoing tidewater flow. Electricity generated is sold back onto the grid; some of the world’s largest tidal barrages boast power generation capacities exceeding 250MW; they work by closing valves during high tide while opening them during low tide for water flow through, which causes one side of the barrage to drop while rising on another side – this process repeats four times daily during two rising and two falling tides!
Tidal power plants with barrages require much larger concrete structures and therefore costlier to construct than single turbine projects, but also have greater environmental impacts. A tidal barrage prevents fish from migrating in and out of estuaries, alters silt flow patterns, alters local ecology, causes local plants to die off quickly as they struggle against silt build-up, alters marine life migration routes and changes salinity of surrounding seawater, as well as displace local populations altogether.
Tidal lagoons are another form of tidal power plant. This technology employs tidal turbines in a natural lagoon rather than building an artificial barrage, producing less destructive electricity while producing less. Although not suitable for all sites due to blocking shipping lanes and inhibiting sediment flow to seabed.
Modern tidal power plants usually utilize a dual-basin design to increase flexibility when producing power, yet due to differences between tide range and current speeds, constant production cannot always occur.
Tidal energy can provide renewable energy solutions to remote communities, meeting power and water requirements in coastal and island regions that lack access to commercial supplies. Furthermore, it may aid disaster recovery by powering critical facilities like desalination plants.
Marine current power
Scientists are developing technologies to harvest this energy and convert it to usable power; some harness the surface motion of waves while others utilize pressure fluctuations subsurface for this purpose. Although marine energy shows great promise as an environmentally friendly renewable source of power, research in marine energy remains at an early stage.
At present, research efforts focus on harnessing energy from tidal and ocean currents through techniques such as tidal barrages, wave energy converters, and marine current turbines. The Department of Energy supports this research through the Water Power Technologies Office; however, its investments may be lower than other government agencies due to high capital costs associated with such systems.
Development of new technologies is important, but testing these devices in real life environments is equally as critical to ensure they perform as intended. Therefore, field trials of such devices should be undertaken so researchers can uncover ways to cut costs while increasing performance.
Tidal and ocean current power can offer reliable, renewable, and sustainable sources of energy for homes, businesses, and communities alike. In particular, remote island communities that rely heavily on expensive fossil fuel shipments could benefit greatly from local access to this form of power – something which violent storms could deprive them of accessing.
Marine current energy conversion holds vast potential and could one day power the planet. It provides a renewable source of energy that could replace fossil fuels while producing clean energy without emitting greenhouse gasses; however, many challenges still must be met before becoming reality.
First and foremost is understanding the dynamics of tidal and ocean current energy resources. For this, scientists need to examine wave and tidal power resources such as their spatial/temporal variability as well as hydrodynamics before modeling these phenomena and using this knowledge to design efficient marine energy technology; including testing prototypes against their performance criteria while considering environmental impacts as well as creating innovative solutions.
