The ocean. It covers over 70% of the earth’s surface. It contains 97% of the earth’s water. The sea is home to millions of lifeforms of all shapes and sizes. With such a vast resource at our disposal, why have we not made more progress in utilizing the ocean for energy? Don’t we owe it to our planet’s future to tap into every source of energy we can to prevent climate change and global warming? Thanks to a recent boost from the United States Department of Energy, ocean-powered renewable energy stands to become a booming business.
“How,” people ask, “are we supposed to tap into something as huge and untamable as the ocean for our energy needs?” A fair question. Scientists can take a variety of different approaches in order to capture much-needed renewable power.
Perhaps surprising to some, the ocean provides near-limitless access to wind energy. Of all the methods undergoing research and implementation, offshore wind has made the most progress. Like land-based wind farms, offshore turbines capture wind and store it as electricity. Transformer stations located on these wind farms connect directly to power grids to ensure that there is a constant supply of energy.
Wind farms have grown significantly in size since early development began. That trend is only going to continue. Now, companies plan for larger wind energy farms housed in deeper waters. Floating plants offer some promise but they come with their own set of challenges. Namely, harsh environmental conditions and high wind speeds regularly damage turbines used to collect energy. Technology must improve in order to stand a chance against Mother Nature.
One of the proven methods for generating energy from the ocean utilizes the tides. Companies have used this technology commercially since the mid-1960s. La Rance tidal power station in France is the first plant specializing solely in tidal energy. Since then, other countries built plants of their own. Canada, China, and Russia have all taken advantage of this technology, albeit on a smaller scale.
Tidal power plants function similarly to those found at reservoirs. Water masses move back and forth with the flow of the tide. At high-tide, water flows upstream through large turbines and flows back through at low-tide. Energy generated by these means rivals that of traditional gas-fired power stations. Several countries seek to develop tidal power plants of their own. They report that the energy generated could provide for as much as 20% of their total annual power consumption.
There are other, lesser known, renewable technologies in development to harness the abundant power offered by the world’s oceans. One of the most promising in development is wave energy. Like it sounds, this method involves generating power using ocean waves. Still in the developmental and refining stages, there are several ways that researchers hope to harness this vast energy resource.
- The “Oscillating Water Column” utilizes a relatively simple air-filled chamber. Wave action displaces the air and forces it into a turbine that generates electricity. Japan, Portugal, and Scotland have all built pilot facilities for this technology.
- Spain and Portugal both plan to build “Oscillating Bodies” facilities. This method generates electricity using the motion of ocean waves. Some systems use semi-submerged generators on floats; others contain components that move against one another and put hydraulic oil under pressure. This pressure drives a turbine that produces electricity.
- In Norway and Denmark, researchers use the “Overtopping” principle. These devices use reservoirs filled by incoming waves. Reservoirs sit at levels above that of the surrounding ocean. As the water falls back through, it drives a turbine.
Temperature Difference-Derived Energy
Though lesser known by the wider public, there is massive potential in energy derived from differences in temperature in ocean water. Ocean thermal energy conversion (OTEC) takes advantage of the temperature differences between ocean water at various depths. Warm surface water and cold deep water work together to drive the evaporation and condensation of a liquid. Because of temperature difference requirements needed to drive the steam cycle, this method works best in warmer marine regions.
In this method, a liquid with a low boiling temperature evaporates when exposed to warm water. The steam produced powers a turbine. Cold water from the ocean’s depths then cools and condenses the steam back to liquid form.
Governments and power companies have now made great progress in pursuing this renewable energy source. Until recently, the cost of building OTEC facilities prevented its widespread use. Public institutions and businesses in France have expressed interest in promoting ocean-based renewables, specifically those utilizing OTEC. A joint American and Taiwanese venture also aims to construct a facility in Hawaii.
Salt Content-Derived Energy
Osmotic power plants are the most novel advancement in deriving power from the ocean. These plants take advantage of the difference in pressure between freshwater and saltwater. When pumped into a double chamber separated by a membrane, the water builds up massive amounts of pressure. This generated pressure powers a turbine.
Still in its infancy, construction on an osmotic power plant began in Oslo in 2009. Experts use this facility primarily to develop the technology. Though, with continued innovation, researchers estimate that this renewable energy source could generate 2000 TWh of power. (For comparison, in 2008, the world electricity production was 20,279 TWh.)
Promising as these technologies might be, many of the companies developing them are small, making it difficult for them to get the financial backing they need. For that reason, they rely heavily on government subsidies. Compounding the economic issue, the size of ocean-powered facilities has to be large in order to be commercially viable in the long term.
The interest in investment is there, though. International governments have all expressed support for ocean renewables. The United States Department of Energy and the European Union have both pledged to invest over $100 million in the development of power plants and facilities.
Despite the enthusiasm for and financial promises to companies developing renewables, it is government bureaucracy that has proven to be an issue. In countries like Germany, one agency handles the approval process. However, in the United States and other countries, this process involves several different agencies and departments. This makes it difficult to fast track any effective, emerging energy production.
More than governmental hindrance, researchers also examined the environmental stressors that could have major impacts on the world’s oceans. Energy removal effects, presence of devices, chemicals, acoustics, and electromagnetic fields all stand to impact marine ecosystems. These stressors could affect the physical environment, fish and fisheries, marine birds and mammals, and the food chain itself.
Critics fear that tidal power plants could destroy nature reserves and bird sanctuaries. Environmentalists believe that damage to local ecosystems could be substantial. As with any new technology, it is hard to determine the environmental effects without having large scale facilities to observe.
There is still much work to do in order to address existing environmental concerns and to develop an understanding of any potential negative impact. Whatever the future of ocean renewables holds, experts, researchers, and regulatory bodies must be vigilant in ensuring the smallest degree of environmental disruption possible.
What are your thoughts on the future of renewable energy sources from the ocean? Do you think that they will one day rival fossil fuel consumption, traditional wind power, or solar energy? Should scientists meddle in ocean energy considering the possible environmental effects? Share your thoughts on the future of energy in the comments section below.