Shock Wave: Electricity From The Ocean

Some renewable technologies harness the vast mechanical power available from a planet that is in constant motion. Wave power generators (WPGs) are a possible energy source of the future, but how do they compare with their rivals?

First published in UCD College Tribune

Even in this futuristic world of ours, all our electricity is generated by simply spinning a turbine. The fossil fuels which are bringing us ever closer to a complete climate catastrophe are not just used to power our cars, but also to create steam which generates the electricity needed for everything from phones to lightbulbs. This is exactly the same principle employed by nuclear power plants. In both cases, fuel is used to create heat, which is used to generate electricity. There are ways, however, to generate electricity which do not require heat at all. Some renewable technologies harness the vast mechanical power available from a planet that is in constant motion. Wave power generators (WPGs) are a possible energy source of the future, but how do they compare with their rivals?

It is worth quickly comparing ocean energy and wind energy since the two are similar in a number of ways. This is why underwater turbines closely resemble those of wind farms. A major difference between the two is the potential energy contained within. Water is nearly 800 times denser than air, meaning that the same volume, travelling at the same speed, contains much more power. What this means on the practical side is that much smaller devices can produce the same yield of energy.

A major difference between WPGs and tidal power is the source of energy. Tides result from the gravitational pull of the moon dragging water up and down our shores as it passes by above us. WPGs, alternatively, find their energy source in the sun. Solar radiation does not heat the earth evenly. The air in places which receive more heat rises upwards, allowing colder air to rush in to take its place. That rushing of air is what we call wind. Since wind is the driving force behind waves, any energy that we harvest from waves comes indirectly from the heat of the sun. It is for this reason that WPGs are considered a renewable technology.

Tidal power is perhaps the most reliable source of energy on earth. Twice a day like clockwork, unimaginably vast quantities of water rush in and out of our coasts. Globally, there is as much power available from tides alone as there would be from nearly 5 and a half billion coal-burning plants. One of the problems, however, is that only a very small fraction of this energy could actually be harvested. There are only 40 or so places in the world where the difference between low and high tide is great enough to produce a worthwhile amount of power. One way that the power of the tides can be harnessed in such places is by building tidal ‘barrages’. These consist of huge dams which trap water from the rising tide, then release it slowly when the tide is low. As the water passes through the dam back into the sea, it spins a series of turbines to generate electricity.

WPGs come in a variety of forms. One very cool design that was deployed in the ocean as far back as 2004 resembles a giant sea-snake. Each segment of the snake is attached to the next by hinge joints which are connected to hydraulic rams. As the sections of the snake move back and forth over the waves, the hydraulic rams drive a series of electrical generators.

Another simple yet ingenious way of harnessing the power of waves is by using a device known as an oscillating water column (OWC). These machines consist of a hollow cylinder containing a turbine which is attached to a buoy. As the waves pass by underneath, air is forced up through the cylinder, spinning a turbine. What makes these devices truly remarkable is the special kind of turbine contained within. The so-called ‘Well’s Turbine’ is shaped in such a way that it can generate electricity regardless of which way the air is flowing. This means that power can be harnessed when the device is rising to the crest of a wave and also when it is falling to a trough, doubling the overall efficiency.

The final method for generating electricity from the ocean is called ocean thermal energy conversion (OTEC). This is another way we can indirectly generate solar energy using the ocean as a middle man. The way OTEC works is that a liquid with a low boiling point (like ammonia) is evaporated by the warm surface water of the ocean and expands, spinning a turbine. The ammonia vapour is then condensed using cold seawater and returned to the evaporation chamber to start the process over again.  The technology required for this method is simple and rapidly improving, meaning that OTEC is very much one to watch out for in the coming years.

So, which is better, WPGs or tidal barrages? WPGs hold greater promise in my view, largely because tidal barrages can be devastating to already strained marine ecosystems. Think about it; much of the ocean’s life is concentrated close to the shore. As the tide rises, both water and marine life can pass freely through the dam. Once that waterway is shut, however, the only way back to the sea is through a series of rotating blades. Many barrages are built on estuaries where rivers meet the sea. By preventing free movement through these estuaries, barrages can also seriously disrupt the spawning patterns of fish like salmon. WPGs, floating on the surface in open water, are much easier to build in a way that’s hospitable to marine life.

This is of vital importance; through plastic pollution, overfishing and ghost fishing, we have already utterly decimated almost all marine life. With plastic pollution and ocean acidification set to get much worse, we simply cannot afford to do any more harm to the beautiful animals that reside beneath the waves. If a plan is to be truly environmentally friendly, it must consider not only the CO2 it will emit, but also the effects it will have on our fellow animals. It is this major issue, coupled with the location problem mentioned earlier, which means that WPGs hold more promise than tidal barrages. In any case, it is clear that as both the financial and environmental costs of fossil fuels rise in the coming decades, blue power will assume an increasingly important position in the global energy industry.

The New Frontier: Plastic Pollution in the Ocean

Every minute, the equivalent of a truckload of plastic enters the sea. Since 2004, humans have produced more plastic than we did in the previous 50 years combined. As the global population rises, our need for cheap and sturdy materials rises with it. The problem with plastics is that they are too sturdy. Every piece of plastic ever produced still exists somewhere in the world. Once the plastic has finally disintegrated, that is by no means the end of the problem. Plastics in the ocean break down into tiny particles known as microplastics. Such particles are found throughout marine ecosystems; from the stomachs of fish, to the stomachs of the seabirds who eat them.

Every minute, the equivalent of a truckload of plastic enters the sea. Since 2004, humans have produced more plastic than we did in the previous 50 years combined. As the global population rises, our need for cheap and sturdy materials rises with it. The problem with plastics is that they are too sturdy. Every piece of plastic ever produced still exists somewhere in the world. Once the plastic has finally disintegrated, that is by no means the end of the problem. Plastics in the ocean break down into tiny particles known as microplastics. Such particles are found throughout marine ecosystems; from the stomachs of fish, to the stomachs of the seabirds who eat them.

Microplastics are not only dangerous, but also extremely difficult to clean up since they are spread out by currents all across the sea. In order to be classified as a microplastic, a piece of plastic debris must be roughly the size of your little fingernail or smaller. There are over 320 million cubic miles of water in the world’s oceans. For a sense of scale, you could fit roughly 320 million cars into a single cubic mile. Scientists have estimated that there are up to 50 trillion pieces of microplastics in the oceans. Given these figures, to say that removing microplastics from the ocean is no easy task would be the understatement of the century.

The reason that high levels of plastic in the ocean are problematic is that plastics have serious detrimental effects on the health of almost all ocean life. Over 800 species of animals have so far been shown to be negatively affected by plastic pollution. Considering that number was closer to 600 in 2012, it is safe to assume that the figure will continue to rise dramatically in the coming years. What’s more, almost 20% of the animals shown to be affected by plastic pollution are already classified as endangered due to human activity. There are two major ways in which plastics can harm or kill marine life. First, they can be ingested. When marine animals ingest plastic, the pieces can remain in their stomachs for the rest of their lives. As the amount of plastic increases, the space remaining in the stomach decreases, causing the animal to starve. In addition to this, most plastics are toxic to animal life, causing conditions like cancer and birth defects. Second, marine animals can become entangled in the plastic. If this happens at a young age, the plastic can restrict the growth of the animal, causing them to become severely deformed. This is seen most often in sea turtles. The worst offenders when it comes to entanglement are pieces of discarded fishing gear.

The phenomenon of marine life being caught by gear that has been abandoned by fishermen is known as ‘ghost fishing‘. Nets, hooks, lines, and cages continue to catch and kill fish long after the fishermen have stopped using them. Roughly 30% of all fish that are caught by humans are caught in ghost fishing gear. When you consider the sheer scale of human fishing, this percentage is astonishingly high. Leaving plastic fishing gear in the ocean, plastic or otherwise, is both short-sighted and despicable. Fishing gear is specially designed to kill as much marine life as it can. When it is under the control of a fisherman, protected marine life like whales and sea turtles can be avoided or released. Even so, fishing of any sort is devastating to endangered species. When the gear is abandoned, however, there is no targeting of species, leading to indiscriminate destruction of marine habitats.

There have been a lot of stories in the news recently about how companies like McDonald’s and Starbucks are ditching plastic straws. While this is a step in the right direction, straws only account for roughly 1% of the plastic debris in the ocean. In order to make a real difference, the companies would have to stop using plastic straws, containers, bags, cups, lids and everything else. This is a perfect example of what’s known as corporate ‘greenwashing’. If the public perception of a company is that they are trying their best to reduce the environmental damage they are causing, less people will boycott the company’s products, leading to higher revenue. Because of this, companies make the calculated decision to sacrifice a small portion of their profits in order to further their public personas as stewards of the environment. This is not to say that small steps forward like those taken by McDonald’s and the like are not helpful. Carlsberg have recently announced that they are ditching the plastic rings connecting cans in favour of glue dots. This is a positive development, since these connector rings have been shown to strangle and stunt the development of marine life and seabirds.

Plastic is not distributed evenly throughout the ocean. There are 5 major places, known as gyres, where currents have forced plastics to accumulate into huge expanses of debris. The largest of these gyres is called the great pacific garbage patch (GPGP) and contains about 2 trillion pieces of plastic. That’s 250 pieces of plastic for every human on earth in just one place. The GPGP is around the size of Texas and weighs about the same as 500 jumbo jets. The accumulation of plastic in gyres like the GPGP makes it somewhat easier to clean up oceanic plastic, but it is still a monumental challenge.

When he was just 17, Dutch aerospace engineering student Boyan Slat devised a huge U-shaped machine to clean up the GPGP that he believes could clear 50% of the plastic in just 5 years. The device uses ocean currents to move with the plastic, but since it is largely above the surface, it moves faster than the plastic, gathering it as it goes. It was deployed in the gyre in September of last year but was immediately faced with a slew of setbacks. The device was not travelling fast enough, allowing some of the plastic to escape, then a 60-foot section of the machine broke off, meaning that it had to be brought back to shore for repairs. Another issue with the device is that it cannot collect microplastics. However, it is important to gather up as many of the large pieces of plastic as we can now, since they will become microplastics in the future which will be much more difficult to clean up. We are in full damage control mode.

Despite valiant attempts to reduce our plastic consumption and remove the plastic we have already dumped in the ocean, it is highly unlikely that this problem will be solved any time soon. If anything, it will get much much worse. Humans have a history of showing up at a new location and decimating the native wildlife populations. When we first arrived in Australia, huge animals roamed the land. These included a 2-and-a-half-ton wombat, a flightless bird twice the size of an ostrich, and a predatory marsupial the size of a tiger. Within a few thousand years of humans showing up, 23 of the 24 animals that weighed over 50 kilograms had become extinct. We have spread all over the planet now, leaving only a few havens in which animals may thrive. The new frontier of animal extinction is marine life. Plastic pollution, overfishing and ghost fishing have devastated marine life and seabirds already, and the rate of destruction is only going to increase. All we can hope for is that people wake up to the genocide we are committing under the waves in time to save at least some of the majestic creatures who call the sea their home.

A Pulsing Sea – The Effects of Seismic Airguns on Whale Populations

Whales are notoriously vocal animals. Indeed, the catalyst for the ‘Save the Whales’ campaign of the 1970s can be said to be the release of the album ‘Songs of the Humpback Whale’ recorded by bio-acoustician Roger Payne. This was the first time that the public was able to hear and appreciate the astonishing variety and beauty of the Humpback’s songs. This love affair with the whales came in the nick of time, since the humpback population had at that time fallen to a historic low. It is estimated that by the late 1960s, over 90% of humpbacks had been wiped out by human activity.

Updated 04/04/2019

Whales are notoriously vocal animals. Indeed, the catalyst for the ‘Save the Whales’ campaign of the 1970s can be said to be the release of the album ‘Songs of the Humpback Whale’ recorded by bio-acoustician Roger Payne. This was the first time that the public was able to hear and appreciate the astonishing variety and beauty of the Humpback’s songs. This love affair with the whales came in the nick of time, since the humpback population had at that time fallen to a historic low. It is estimated that by the late 1960s, over 90% of humpbacks had been wiped out by human activity.

Since the early 1920s, a technique known as ‘reflection seismology’ has been used to locate reserves of natural resources such as oil, gas and salt. Reflection seismology operates on much the same principle as sonar. Sound waves are emitted which reflect off the sea floor and are then measured by an array of sensors. Using this technique, areas of the sea floor can be accurately mapped, and it is possible to determine whether natural resources lie beneath the rock.

Modern reflection seismology is carried out using huge arrays of seismic ‘airguns’. These airguns can produce sounds of up to 240 decibels, over twice the volume of a standard rock gig. What’s worse, this noise level is produced every 10 seconds, 24 hours a day. According to Oceana, a single survey ship may carry up to 96 airguns at a time. 

Whales and dolphins use sound to communicate with each other and, in some cases, for the echolocation of prey. Although insufficient research has been conducted to ascertain the detrimental effects of seismic testing on whales, preliminary data shows that almost all cetaceans give seismic airguns a wide berth. Further, sightings of cetaceans fall significantly when seismic testing is being conducted in a given area.  Even in the absence of solid data, mere common sense dictates that the levels of noise produced by seismic testing may well prove to seriously harm the hearing of cetaceans, as well as disrupting their feeding, mating and migratory habits. In any case, if reflection seismology is at all likely to damage already strained marine environments, it is imperative that we halt that practice before the damage is irreversible. 

It is not just whales that are at risk. During periods of seismic testing, local fishermen have reported an increase in dead fish floating in the sea. Squid, crabs and fish eggs have also been shown to be harmed by seismic airguns. It seems, then, that as well as deafening and disorienting endangered whales, seismic testing is also harming their ecosystem and thus limiting the availability of their prey. One study found that the number of zooplankton – tiny creatures that are the backbone of marine ecosystems – fell by 64% within 1,219 meters of airgun activity. That is guaranteed to have huge knock-on effects not just for whales and dolphins, but for all ocean life. 

On the 1st of February 2018, seismic airgun testing off the coast of Newcastle, Australia was approved by NOPSEMA. The tests, which will be carried out by Asset energy, are approved right up until the 31st of May, with the whale migration set to begin around the 1st of June. This has been met with serious resistance. Greenpeace Australia campaigner Nathaniel Pelle noted that “Whales and other endangered species do not adhere to the Gregorian calendar and do not know the difference between May 31 and June 1”. The fact that this must be noted at all speaks to the greed and short-sightedness of regulators and fossil fuel companies.

In December of 2018, the U.S. (under the command of Donald Trump) began extensive seismic surveys of the entire east coast. This happened despite vehement opposition from almost all U.S. environmental agencies and state governments. The area which the U.S. has begun to survey is the home and breeding grounds of the North Atlantic Right Whale, a species so endangered that there are less than 500 of them alive today. 

A final and crucial point to consider is that even if seismic tests did not damage marine populations directly (which they certainly do), they are a gateway to offshore drilling, a practice which damages marine populations in a number of ways. First, there is a possibility of oil spills which, as we all know, can be cataclysmic events for marine ecosystems. Further, when the oil is successfully extracted, it will be burned as fuel, releasing carbon dioxide into the atmosphere and accelerating the already severe effects of climate change. Renewable energy sources such as wind, solar and wave energy are the planet’s last hope for any sort of meaningful recovery. One may consider it an added bonus, then, that these energy sources do not require that we seriously harm marine species while they attempt to recover from the immeasurable damage that humans have already inflicted upon them.

Sources

Beachapedia – Seismic Surveys

Bielby, Nick – NOPSEMA accepts environmental plan for seismic testing off Newcastle coast and Concern over plan for seismic test off the coast of Newcastle

Gordon, Jonathan C.D et al. – A Review of the Effects of Seismic Survey on Marine Mammals

Greenpeace Australia – Humpback whale migration threatened by seismic blasts

Hannam, Peter – ‘Whales don’t follow the Gregorian calendar’, opponents of seismic testing say

Stone, Carolyn J. and Tasker, Mark L. –  The effects of seismic airguns on cetaceans in UK waters

Photo Credit: Maui Magic