CCell Provides the Energy to Save Coral Reefs

British wave energy start-up Zyba has teamed up with Biorock, which builds artificial coral reefs with the hope of simultaneously providing energy and coastal protection for islands. It has developed a new curved technology, the CCell, with a lightweight design that allows it to capture a greater amount of the ocean’s awesome power than its competitors.

Working with Biorock – both the company and technology name – Zyba hopes to provide island communities with a new source of clean and reliable energy. The power will also be used in the construction of coral reefs, which provide important coastal protection and bustling ecosystems for marine wildlife.

Hidden among the reefs, the CCells will take advantage of the total theoretical global wave energy potential of 32 petawatt (PW) hours per year. So far, no large-scale application for wave technologies has been successful and so Zyba is championing a smaller-scale approach. The power it creates is designed to enter the grid network and work alongside other renewable sources.

Symmetric vs asymmetric wave energy devices

The concept of the CCell arose from the company’s founder, William Bateman, asking a simple question: “The energy in the ocean leads from the open ocean towards the shore, so it’s an asymmetric problem,” he says. “All I fundamentally did was question why are people making symmetric devices.

“I never meant to start a business in wave energy but I was looking at their devices and they were all symmetric, so they were either round or they were flat.”

Bateman went to University College London in 2012, where he asked friends to test a curved panel against a flat one. The results came back vastly in favour of a curved panel, which moved 40% more than the flat one, based on wave motion. As testing continued, researchers showed that as the wave hits the face of the panel, the curved shape forces the energy towards the central core where it could be collected. Additionally, the shoreward face of the panel is subject to less stress than a flat panel because the convex shape cuts through the water smoothly, reducing the risk of the panel becoming damaged in rough weather.

From this point, the project snowballed into Zyba and the patented CCell technology. With prototypes and testing complete, the final CCell was made comprising a glass and carbon fibre composite, making it light, flexible and, importantly, corrosion-resistant to increase its lifespan in seawater. There is only one moving part in each of the modular units and it has the highest known power-to-weight ratio of any wave device.

A symbiotic relationship protecting reefs

Zyba aims to tackle energy problems that large sources, such as offshore wind, cannot. “We have really moved away from using wave power for grid-scale electricity generation in the short term, but instead really trying to carve out a niche where wave energy is unique and actually has a significant intrinsic benefit,” says Bateman. “That’s really come about in the last six to nine months. Our focus at the moment has really been on coastal protection using a combination of the CCells and our partner’s technology, which is called Biorock.”

Biorock has been developed over the last 30 years by Professor Wolf Hilbertz, who died in 2007, and Dr Tom Goreau, as a way to grow artificial concrete. Biorock uses electrolysis to create a limescale-like substance by attracting the minerals in seawater. The rock this creates grows incredibly fast, as much as several centimetres a year, and is incredibly strong.

“The biggest single challenge for Biorock has always been its thirst for power at sea, conversely, we’re coming into a market where we are generating this power at sea and we need to get it to shore,” explains Bateman.

The companies have thus formed a partnership that allows them to build artificial concrete that protects coastal areas, while bringing in revenue from renewable energy production. “By collaborating with Biorock we are developing a symbiotic relationship in which we provide them with the power that they need,” says Bateman. “Equally, we can position our device where Biorock is growing a reef, so they are providing protection and fundamentally mass which helps to keep our unit in position.”

Clean and cool energy, despite challenges

As a start-up, Zyba’s main challenge throughout development has been financing. “For a physical product, where you have to do lab testing or actually offshore deployments, the costs are relatively high,” says Bateman. “When you’re doing the research and testing, you don’t really have time to be applying for funding, and then you get to the end of one round of funding and you have to stop and think, where am I getting the next bit? Obviously, you try to overlap them but often the funding doesn’t overlap so you do spend a lot of time and concern on how to grow in a sensible way.”

However, increased recognition for the technology over the past year has led to greater opportunities. Zyba was chosen to be part of the Clean+Cool Mission, organised by Long Run Works and sponsored by Innovate UK and the Department of International Trade it connects start-ups with investors in Silicon Valley, California, and allows entrepreneurs to share and develop ideas.

“Earlier this year we were selected alongside a group of 19 other companies to represent the greatest and the best of UK clean tech,” says Bateman. “It’s really interesting talking to the people over there because their attitude to start-ups is very, very different to what we see in the UK. It’s almost like everyone has a start-up, everyone’s got something going on in their garage and it’s all very chaotic.”

The trip encouraged the Zyba team to work on making changes in big increments by targeting smaller savings, leading to a focus on the nitty-gritty of the supply chain. “We originally thought that we’d manufacture the devices in the UK because the tooling behind the construction of our composite paddles was one of the major costs,” says Bateman. “Over the last six months we’ve actually been able to drive down the cost of our tooling for our relatively small device, from about £50,000 down to almost £2,500. The cheaper tooling is actually a better product – it’s a better module than the one we’d been quoted £50,000 for.”

Following Clean+Cool, Zyba decided to ship flat pack paddle moulds instead of the paddles themselves. It will provide local craftsmen, particularly yacht builders who are used to the required composite materials and methods, with the moulds and tools to make the CCell close to where it will be installed. This will help reduce the cost of the CCell, as well as supporting local communities.

Connecting wave energy to the grid

Zyba hopes the first CCell will be running offshore next year. “We are working really hard to get a row of devices installed just off the coast of Mexico,” says Bateman. “Hopefully by January, at the latest March, next year, it’ll be installed. What’s constraining us at the moment is overcoming some of the regulatory hurdles.”

CCells will be positioned along the coast of the island of Cozumel, starting with just one module. “The vision is that you would install one just to start with, just to make sure that you understand the local conditions and everything is correct, and then in the following years install in a line of devices along the shore,” explains Bateman.

Energy will then be transported underground to the island, where it will enter the grid system and work alongside other power sources. “Give or take 10%-20% of the energy that we generate will be needed to grow the Biorock, and the rest of that power we can then provide as an export to shore,” says Bateman.

The CCell could help provide clean, renewable power for small island communities, while protecting the coast and the underwater environment from the ocean. It’s a technology that kills two birds with one stone, and showcases a lot of potential on a small scale.

CCell: the energy to save coral


Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months

marine science and engineering

Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months

Thomas J. F. Goreau 1,2  and  Paulus Prong 2,3

Global Coral Reef Alliance, 37 Pleasant Street, Cambridge, MA 02139, USA
Biorock Indonesia, Bali 80361, Indonesia
Pulau Gangga Dive Resort, Sulawesi 95253, Indonesia
 
Abstract
Severely eroded beaches on low lying islands in Indonesia were grown back in a few months—believed to be a record—using an innovative method of shore protection, Biorock electric reef technology. Biorock shore protection reefs are growing limestone structures that get stronger with age and repair themselves, are cheaper than concrete or rock sea walls and breakwaters, and are much more effective at shore protection and beach growth. Biorock reefs are permeable, porous, growing, self-repairing structures of any size or shape, which dissipate wave energy by internal refraction, diffraction, and frictional dissipation. They do not cause reflection of waves like hard sea walls and breakwaters, which erodes the sand in front of, and then underneath, such structures, until they collapse. Biorock reefs stimulate settlement, growth, survival, and resistance to the environmental stress of all forms of marine life, restoring coral reefs, sea grasses, biological sand production, and fisheries habitat. Biorock reefs can grow back eroded beaches and islands faster than the rate of sea level rise, and are the most cost-effective method of shore protection and adaptation to global sea level rise for low lying islands and coasts.
 
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
 
 

1. Introduction
 
Accelerating global sea level rise is now causing almost all beaches worldwide to erode [1]. The current rate of sea level rise, now 3 mm/year [2], will accelerate greatly in the future as the melting of ice caps increases, masked by shorter term regional fluctuations driven by local weather [3]. IPCC projections of sea level rise are often thought by the public to represent the end point of sea level rise response to fossil fuel CO2, but in fact they are merely points along the first 5, 10, 20— or at most 100—years, of the initial rise of a curve that will continue to increase for thousands of years. The time horizons for IPCCC climate change projections were chosen for political purposes, not for scientific ones, and therefore miss the vast bulk of the real world long-term sea level and temperature responses to increased greenhouse gases [4].
 
Since the ocean holds nearly 93% of the heat in the Earth ocean-atmosphere-soil-vegetation-rock-ice system [5] and it takes around 1500 years for the ocean to mix and turn over [6], Earth’s surface will not fully warm up until after the deep ocean waters, now about 4 degrees above freezing, heat up. Global temperatures and sea levels lag thousands of years behind CO2 increases because of ocean mixing, so we have not yet really begun to feel the inevitable temperature and sea level responses. Because of these politically chosen time horizons, IPCC projections do NOT include more than 90% of the long-term climate response to changing CO2 [4,7-9]. By greatly underestimating the all too real long-term responses of temperature and sea level, they have lulled political decision makers into a false sense of complacency about the magnitude and duration of human-caused climate change or the urgency of reversing them before the really serious impacts hit future generations [4].
 
Improved estimates of long-term global climate impacts are made from actual paleoclimate records of changes in global CO2, temperature, and sea levels from the Antarctic ice cores, deep sea sediments, and fossil coral reefs over the last few million years [7,9]. The last time that global temperatures were 1-2 °C above today’s level, sea levels were about 8 m higher, crocodiles and hippopotamuses lived in swamps where London, England, now stands (Rhodes Fairbridge, 1987, personal communication) [10,11], and CO2 levels were around 270 ppm, around 40% lower than today [7,9]. Comparison of long-term global climate change records suggests that the steady state climate for the present (2017) CO2 concentration of 400 ppm, once the climate system has fully responded, are about 17 °C and 23 m above today’s levels [9]. We are committed to such changes even if there is no further CO2 increase starting right now because of the excess already in the atmosphere, unless that is reduced. No amount of emissions reduction can reduce excess atmospheric CO2, only increased natural carbon sinks with storage in soil and biomass carbon can draw down the dangerous excess in time to avert extreme long term changes [4,8,12], which would last for hundreds of thousands to millions of years. Perhaps the largest cost of adaptation to climate change will be the cost of protecting low lying islands and coasts from being flooded by global sea level rise.
 
Beach erosion is largely controlled by refraction of offshore waves by bottom topography [13]. The reflection of waves by steep cliffs prevents any accumulation of sand at their bases. In contrast, shallow sandy beach fore-shores are almost always protected from waves by reefs, Waves are refracted as water passes through porous and permeable reef structures, without being reflected.
 
Conventional methods of shore protection rely on “hard” solid structures like sea walls and breakwaters that are designed to reflect waves, like rock cliffs. This concentrates all the energy of the wave at the hard, reflecting surface, and the force on the structure itself is twice the momentum of the wave due to the reversal of the wave direction vector [14,15]. The inevitable result of this energy focusing is that first all the sand is washed away in front of the structure, and then is scoured away underneath it until the structure settles, cracks, falls apart, and needs to be rebuilt. These structures protect what is behind them until they fall down, but they cause erosion in front of them and guarantee loss of sediment. All such structures are consequently ephemeral and will fall down sooner or later, depending on how large and strong they are.
 
This is well known to coastal engineers but most feel there is no alternative to impermeable solid walls, even though so called “porous” or “permeable” breakwaters, made of small distributed modules shaped like coral reefs, with holes within structures and passages between them, seem to protect shores with much less material and with greatly reduced reflection. But we could find no experimental or theoretical modeling literature on porous permeable structures like natural coral reef structures found by searching on Google Scholar. Most search results for porous breakwaters were for solid rock walls with crevices between stones rather than reef-like structures with a much greater range of pore and spacing sizes, capable of interacting with waves over larger wavelength ranges.
 
Coral reefs provide the most perfect natural shore protection, dissipating around 97% of incident wave energy by frictional dissipation [16]. Healthy reefs produce sand as well as protect it, and rapidly build beaches behind them. They are sand factories, generating vast amounts of new sand, largely remains of calcareous green and red algae. Every grain of white limestone sand on a tropical beach is the skeletal remains of a living coral reef organism. Once corals die from high temperatures, pollution, or disease, the previously growing and self-repairing reef framework starts to deteriorate and crumble from boring organisms that excavate the rock [17]. Because of the mass mortality of corals around the world caused by global warming [18-23], tropical beaches that were growing until recently have begun rapid erosion, and islands are washing away because of global sea level rise. 
 
Here we describe the results of a novel method of beach restoration—Biorock electric reef shore protection—which avoids the intrinsic physical flaws of hard reflective structures, and which grows beaches back at record rates at a lower cost, with less materials, and with much greater environmental benefits than seawalls. Biorock electric reefs are grown by low voltage electrolysis of sea water, which causes growth of limestone rock minerals dissolved in sea water over steel surfaces, which are completely protected from corrosion [24,25]. Biorock reef structures can be any size or shape, and are the only marine construction material that gets stronger with age and is self-repairing [26]. When grown slowly, less than 1-2 cm/year, this material is several times harder than Portland Cement concrete [25].
 
Biorock shore protection reefs are open mesh frameworks designed to permit water to flow through them, like coral reefs. The size and shape of the structures, and of the holes in them, determine their performance dissipating wave energy. The electricity needed for electrolysis is safe extremely low voltage (ELV) direct current provided by transformers, chargers, batteries, solar panels, wind mills, ocean current generators, or wave energy generators, depending on which source is most cost effective at the site [27].
 
Biorock reefs in Grand Turk survived the two worst hurricanes in the history of the Turks and Caicos Islands, which occurred three days apart and damaged or destroyed 80% of the buildings on the island [28]. Sand was observed to build up around the bases of Biorock reef structures. In contrast, concrete reef balls nearby caused such severe sand scour around and under them that they buried themselves into the sand, digging their own graves. Solid objects, by forcing bottom currents to accelerate as they diverge around them, cause erosion to a depth of about half the height of the structure, and about as wide as the structure height [29]. Biorock reefs, being permeable and porous to waves, had the opposite effect than reef balls, baffling waves, lowering their velocity, and causing sand deposition instead of erosion [30].
 
The first Biorock shore protection reef was built in front of a beach that had washed away at Ihuru Island, North Male Atoll, the Maldives, in 1997. Sand bags were being piled in front of trees and buildings that were falling into the sea, which the hotel thought they had no chance of saving. The Biorock reef was a linear structure parallel to the shore, 50 m long, about 5 m wide, and about 1.5 m high, built on eroded reef bedrock. The structure cemented itself solidly to the limestone bedrock with mineral growth. Waves were observed to slow down as they were refracted through the structure, dissipating energy by surface friction. Sand immediately began to accumulate on the shore line and under and around the reef, and the beach grew back naturally and rapidly in a few years, and stabilized with no further erosion, even though the 2004 Tsunami passed right over it [30]. Corals growing on the Biorock reef had 50 times (5000%) higher coral survival than the adjacent natural coral reef after the 1998 coral bleaching event [25]. For a decade after the bleaching event this resort had the only healthy reef full of corals and fishes in front of their beach in the Maldives. The hotel whose reef and beach were saved by the Biorock project turned the power off, with the result that the corals, no longer protected from bleaching by the Biorock process [31,32], suffered severe mortality in the 2016 bleaching event.
 
The second group of Biorock shore protection reefs were built at three eroding beach locations at Gili Trawangan, Lombok, Indonesia around 2010. These consisted of 4 to 6 separate reef modules designed to break waves up by slowing down separate portions of the wave front and driving the incoming wave front out of coherence, using less structural materials. The Biorock structures are shaped like an upside-down wave, which is optimal for dissipating wave energy, with no vertical surfaces to cause reflections, and so are called Biorock Anti-Wave structures (BAW). Although these structures were small, new beach growth was clearly visible at all sites within 8 months on Google Earth images [30]. One set of structures was of, and creation of a gap underneath it, so that it was on the way to falling down. One year later the gap underneath had completely filled in, and the sand had risen by about a meter to cover half the vertical wall height. The seawall on the neighboring property, built at the same time, but not protected by Bioorck, completely collapsed within a year [30]. The hotels whose beaches had been restored by the projects then turned the power off. Because the structures, no longer maintained, growing, or protected from rusting, are now collapsing, beach erosion has now resumed, with new sea walls being constantly built and falling down.
 
2. Materials and Methods
 
Pulau Gangga, North Sulawesi, Indonesia, has suffered progressive beach erosion. The index maps show its location on various scales (Figure 1a-d), and Google Earth images show the rapid erosion of the beach between 2013 and 2014 (Figure 2a,b). The site is outside the typhoon belt because it is close to the Equator, but it is affected by both the Australian and Indo-China Monsoons. From around December through May the winds and waves are usually from the southeast. A strong southward tidally-modulated current normally sweeps sand from north to south at the site.
 
The formerly wide sand beach had largely washed away by late 2015, leaving an erosion cliff about 1.36 m high along the shore, with trees falling into the sea, and beach pavilion buildings have had to be repeatedly torn down and moved inland. In front of the 200 m of severely eroded beach we built 48 Biorock Anti Wave reefs in a staggered design to dissipate wave energy before it hits the beach. The time of installation, January 2016, was just before the monsoon season when erosion takes place on this beach, and was done as fast as possible before waves made installation difficult.
 
48 Biorock Anti Wave reefs were deployed in the sea grass beds in front of the eroding beach in January 2016. They were arrayed in twelve groups of four, each group powered by a single power supply located 100 m away on land, connected by electrical cables dug into the sand (Figures 3 and 4a-d). They grow thickest at the bottom, and thinnest on top. The bottom 10-20 cm of the structures were always submerged at low tide, but above this they were exposed to the air for various periods, depending on the tidal cycle. Since structures grow only when and where submerged in salt water, the bottoms are always growing, while the top grows only when submerged, about half of the time. The gabion baskets were deployed in a grid pattern (visible from aerial images below) at low tide in shallow sand, seagrass, and coral rubble.
 
The resort had previously purchased gabion wire baskets for stones to make a breakwater, not knowing that these would quickly rust and fall apart. Because these were already available, they were incorporated into the core of the Biorock Anti Wave structures, because the Biorock electrolysis process prevents any rusting of the steel. The rocks are bound in place by growth of minerals over the mesh and by prolific growth of barnacles, oysters, and mussels, preventing rock shifting in heavy surge from breaking the gabion. There are both advantages and disadvantages to the use of rock gabions in Biorock shore protection structures, as they can cause scour by acting as a near solid wall, but they cause more rapid initial results slowing wave erosion than a more open structure that does not incorporate them. Gabions are not an essential part of the design, in fact not using them makes BAW units much faster and cheaper to construct and deploy. In this study gabions were used only for convenience as they had been previously bought and were already on site. Not to include rocks at all relies purely on the growth of a biological reef to provide long-term growing shore protection, instead of that provided by the rocks.
 
The core of each structure was a double gabion basket, 1 m × 1 m × 2 m with the long dimension parallel to the shore. These were placed on the shallow sea floor at predetermined sites, with the long axis parallel to the shore, and filled in with rounded river stones (largely in the 20-50 cm size range). At the start, the rocks had clean surfaces with nothing growing on them. The gabion baskets were overlain with standard welded steel mesh bars used in local construction, spacing 15 cm, dimensions about 2.1 m by 5.4 m. These sheets were curved into an arc to fit over the top of the gabion basket, with the long dimensions at right angles, so that the long axis of the arc was perpendicular to the shore, oriented into the waves coming over the shelf edge coral reef. They were welded across at the base with support rebars and vertical bars to strengthen them. Each unit was carried by four people at low tide, placed over a gabion basket and wired to it with hose clamps and binding wire. The growth of minerals over the steel cement it firmly to any hard rock bottom, and cement sediment around the bases on sand or mud, firmly attaching the structure to the bottom. The structures sit on the bottom under their own weight and that of the rocks they contain.
 
Beach profiles were measured using the U-tube water level measuring method [32]. They are estimated to be accurate vertically to about a millimeter, and horizontally to about a centimeter, by repeated measurements. The beach profile before the start of the experiment was estimated from photographs taken before and after from the same positions with common objects of known size in the images for scale. The accuracy of the pre-project beach profile estimate is thought to be about 10 cm vertically and one meter horizontally. Unfortunately, the apparatus for making rapid and accurate beach profiles was not built until September 2016, eight months after the start of the project. A second set of measurements was made in January 2017, a year after the start of the project, after a severe storm and at several more intervals since then. Initial beach profiles were estimated by measuring the height of the erosion cliff at the start of the project using the measured height of concrete foundations as a scale.

 

(a)
(b)
(c)
Figure 1. The site shown on Google Earth Images of the location of the project (red star) on decreasing scales: (a) Indonesia, (b) North Sulawesi, (c) Pulau Gangga
 
(a) 23 May 2013
(b) 4 January 2014
(c) 15 December 2014
(d) 4 August 2017
Figure 2. Erosion of the beach prior to the project. Google Earth images from 2013 (a) and 2014 (bshowing short term changes in the beach before the project, the last available image taken near low tide a year before the project began in early 2016 (c), and the first image after the project, taken near high tide 1.5 years after (d). Notice the cores of the Biorock Anti Wave modules as white spots in the seagrass off the regenerated beach. Beach erosion beyond the project near the pier at the south was caused by storm waves from the southeast and longshore drift sand blockage by the solid rock pier. Waves from the northwest shown in (c) are typical during erosion of this westward facing beach. Note the row of pavilions (dark spots) on the edge of the beach erosion scarp and brown dying trees with roots exposed in (c) and how in (d) the roofs are now hidden by new leaf canopies due to prolific tree leaf regrowth after sand buildup around their roots.
 
 
Figure 3. Soon after start of the project, at low tide (wide angle image). The tops of the reef restoration structures are clearly visible. The eroded curve is the area where the beach grew back.
 
 
(a)
(b)
(c)
(d)
Figure 4. Aerial views, oblique at low tide (a) and vertical at high tide (b) on 12 March 2017, fourteen months after the installation, showing the Biorock Anti Wave structures (dark spots in sea grass beds). The northern edge of the project, on the same day at high (c) and low (d) tides. The Red spot in the last image two images is the northern limit of the project.
 
 
3. Results
 
The speed of beach regrowth astonished local residents. The formerly concave beach, ending in an eroding cliff, is now convex in its profile and growing. Large trees that had been dying after sand washed away, exposing their roots to sea water, have leafed out new canopies since the sand built up around their roots.
 
By the time of the first beach profile measurements the eroded beach had almost completely grown back and the erosion scarp, 1.36 m tall, was reduced to about 10 cm. About 80% of the beach grew back in less than 3 months and has continued to grow ever since, even during strong storm conditions that in the past caused severe erosion. Over the course of a year the beach has increased in height by more than a meter, and in width by more than 15 m, over a two hundred meter length, a conservative estimate of an increase of beach sand volume of 3000 cubic meters. Most of the gains occurred in the first two months, but have continued since (Figure 5a-g).
 
The beach growth in the first year was wider at the south than at the north. But there were interesting differences after a severe storm in early January, which caused some erosion of the southern end of the beach, while there was substantial growth of the central and northern sections. Since then the center and north have continued to grow, while the south has continued to erode slowly (Figure 6a-c).
 
(a) November 2015
(b) December 2015
(c) December 2015
(d) May 2016
(e) August 016
(f) November 2016
(g) January 2017
Figure 5. Before & after photos of beach taken at various times: (a) November 2015, beach looking north two months before start of project, tree falling into the sea and roots exposed at beach erosion scarp, (b) December 2015, one month before project, 1.36 m high erosion scarp and foundations of beach pavilions about to collapse near center of beach, (c) December 2015, one month before project, large old tree collapsing into the sea, leaves dying, roots exposed, (d) May 2016, 4 months after project installation, lower branches of fallen tree buried in new beach sand growth, roots buried, new growth, (e) August 2016, seven months after, (f) November 2016, ten months after, (g) January 2017, Twelve months after, soon after a severe storm, looking south. Most of the beach grew after the storm, even though this was the sort of event that had caused heavy erosion in the past. The south end, shown here, was worst affected.
 
 
(a)
(b)
(c)
Figure 6. Beach profiles, measured at different times for the north (a), center (b), and south (c). The Zero reference datum for the central profile is the top of the concrete pillar foundation at the left of the December 2015 photograph. A 1.36 m vertical cliff stood at what is now the zero distance, based on measurements from photographs. Dates of measurements: X and dashed line estimate from January 2016; KEY to symbols: B upward triangle, 21 September 2016; C square, 11 January 2017; D downward triangle, 11 March 2017, E circle, 10 July 2017.
 
There has been prolific growth of hard and soft corals all over the bases of the structures and in intervening areas (Figure 7a-e), prolific growth of sea grasses all around them, dense settlement and growth of barnacles, mussels, and clams on the rocks in the core of the BAW structures, and a rapid increase in juvenile fish and echinoderm populations. In addition, there has been prolific growth of sand-producing calcareous green and red algae around and between the structures.
 
(a)
(b)
(c)
(d)
(e)
Figure 7. Underwater images: One end of a Biorock Anti Wave structures at high tide soon after installation (a), growth of barnacles over smooth river stones inside the gabions (b), examples of rapid growth of corals, sea grasses, and other organisms under, over, and around their bases (ce).
 
Wave fronts are dissipated as they pass through the structures, breaking up the coherence of incoming wave fronts (Figure 8a-c). This dissipation behaves as refraction through permeable structures. But the wave interaction can include a reflective component once structures have grown to be solid with all pores filled in, or if the rock fill is too impermeable to transmit wave pressure through intervening spaces. In that case, sand-eroding scour will be caused, while purely refractive dissipation increases sand accumulation underneath and behind the structure. There is also a diffractive component caused by wave interaction with the metal structure spacing and lattice spacing, which appeared to damp waves at spatial scales that range from the spacing of the metal grid used (0.1 m), the size of the modules (1-5 m), and the spacing of the modules (roughly 10 m).
(a)
(b)
(c)
Figure 8. Diffraction of energy. Incoming wave energy dissipated by interaction with structure these photographs were taken in rapid succession, the middle picture appears brighter because of break in the clouds, and the photographer moved between the first two images. (a) approaching wave, (bwave starting to interact with mesh, (c) wave energy dissipated by friction.
 
4. Discussion
 
We are not aware of any other case in which a badly eroded beach has been grown back so uickly and naturally. In addition, the Biorock reefs have caused prolific growth of corals, barnacles, oysters, mussels, and seagrass, and created a juvenile fish habitat [30]. 
 
Biorock reefs can be any size or shape. Mineral growth extends up to the high tide mark. They can be built entirely subtidal, as at Ihuru, entirely exposed at low tide as at Gili Trawangan, or have only the tops exposed at low tide, as at Pulau Gangga. Since the structures grow only when submerged, those in the intertidal grow most on the bottom, and least on the top. The structures attach themselves solidly to bedrock, and cement loose sand around their bases. Whether the structures are entirely submerged or partially exposed affects their wave mitigating performance. Those that are fully submerged are never visible from shore and generate real coral reef communities or oyster and mussel reefs in muddier or colder waters. Those reefs located in the intertidal zone are visible at low tide, which may be aesthetically objectionable to those who want a clear ocean view from the beach, but they are more effective in protecting the shore if there is a storm during high tide, which would pass over deeper reef structures.
 
The size, shape, and spacing of the modules affect their performance, and cost. What is astonishing is that record beach growth was achieved with far less material and far lower cost than sea wall or a breakwater. Conventional reinforced concrete structures are made by first building a reinforcing bar frame, and the steel is a very small part of the total cost compared to cement, stone, wooden forms, and labor. Since steel in reinforced concrete structures invariably rusts, expands, and cracks the concrete, such structures have finite lifetimes, especially in salty coastal air. 
 
Biorock structural steel is completely protected from rusting, and the continuous growth of hard minerals makes it constantly stronger, and able to grow back first in areas that are physically damaged. The cost is far less than a reinforced concrete structure of the same size and shape, because instead of cement, rocks, labor, and wooden forms we simply provide an electrical supply instead. Estimates of Biorock reef costs range from $20-1290/m of shoreline depending on the size of the reef grown, while other methods range from $60-155,000/m, or 3-120 times more expensive [16]. The amount of electricity used is small, the entire Pulau Gangga beach restoration project uses about one air conditioner worth of electricity.
 
Shore protection provided by Biorock includes both production of new sand by prolific growth of calcareous algae around them, and physical protection from sand erosion by wave energy dissipation. The results of beach growth after the project was installed indicate that beach sand accumulation is a very dynamic function of wave and current interactions with reef structures. Biorock reef structures physically dissipate wave energy and reduce erosion at the shoreline, while also generating new sand. They should slow down transport of sand by north to south tidal currents at the site. That, and the interplay of the structures with waves coming from different directions, may explain why the unusual January 2017 storm seems to have transported sand in the reverse of the usual direction. Further measurements will reveal if this trend continues, or is reversed by sand production from increased calcareous algae growth around the structures.
 
Wave energy dissipation due to friction at the surface of the growing limestone minerals produced by the Biorock process is very quickly exceeded by the much larger, and rougher, surfaces provided by the prolific growth of corals, barnacles, sea grass, and all other living marine organisms as the structure becomes rapidly overgrown. The size, shape, and spacing of the structures, as well as the reef organisms growing on them, affect their performance as wave absorbers, and their designs can be readily changed by adding, or removing, sections as needed. Such structures can be designed to be oyster, mussel, clam, lobster, or fish habitat for highly productive and sustainable mariculture.
 
Biorock structures interact with waves over a very broad range of wavelengths, and are expected to produce wave diffraction on wavelength scales similar to the spacing of the structures—about 10 m—and over the spacing of the mesh—about 10 cm. Since the growing, self-repairing Biorock structures cannot be modelled by conventional hydrodynamic modeling schemes, it will be important to make physical measurements of wave energy around such structures to evaluate actual performance, and to optimize them for beach growth purposes.
 
The initial results of this project resulted in extraordinary beach growth, which could be improved with further experimentation under a wider range of conditions, and should be much more widely applied as a cost-effective beach restoration solution that uniquely restores marine ecosystem  services.
 
5. Conclusions
 
We have grown back severely eroded beaches naturally in months by growing Biorock electric reefs in front of them. These structures cost far less than sea walls or breakwaters and work on entirely different physical principles. They restore marine ecosystems as well as beaches. The exceptionally rapid growth of corals on them [31,33] provides additional shore protection, and the rapid growth of sand-producing calcareous algae on and around them produces new biological sand supplies. These structures can easily keep pace with global sea level rise because solid hard electrochemical minerals can be grown upwards at rates up to 2 cm/year—around 5 times faster than sea level rise—and grow still much faster when corals, oysters, mussels, and other calcareous organisms cover them. As a result, Biorock shore protection reefs quickly turn eroding beaches into growing ones, can protect entire islands and even grow new ones. Biorock is the most cost-effective technology for protecting eroding coasts, for restoring fisheries habitat, and is critically needed to save the low-lying islands and coasts now threatened by global sea level rise, and the billions of coastal people who will become climate refugees if global warming is not rapidly reversed [4,12].
 
6. Dedication
 
This paper is dedicated to the memory of the late Wolf Hilbertz, who first invented the Biorockprocess of growing minerals in the ocean in 1976, and who foresaw all its applications, including shore protection.
 
Acknowledgments: We thank the entire management and staff of Pulau Gangga Dive Resort and its parent company, Lotus Resorts, for their willingness to try new, better, more natural and effective approaches to shore protection. Lotus Resorts paid for all materials, equipment, domestic travel, and time. The authors thank them deeply for their willingness to pioneer innovative methods of shore protection. We also thank Lori Grace for providing funds for a round trip ticket to Indonesia for Thomas J. F. Goreau to construct the device to measure beach profiles. We thank the anonymous reviewers for their constructive suggestions that have improved the original draft.
 
Author Contributions: T.J.F.G. and P.P. conceived, designed, built, and installed the first four Biorock Anti Wave modules and connected them to power; P.P. then built and installed the rest. T.J.F.G. analyzed the data; contributed reagents/materials/analysis tools; and wrote the paper. Although they are not listed as authors, because they did not work on the projects in the water, the entire management and staff of Lotus Resorts, operators of Pulau Gangga Dive Resort, played absolutely crucial roles in the design, logistics, funding, advice, information, and support for the work described. T.J.F.G. is a co-inventor of the Biorock electric technology of marine ecosystem restoration.
 
Conflicts of Interest: The authors declare no conflict of interest.
 
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 © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 

This Coral Restoration Technique Is ‘Electrifying’ a Balinese Village

The technique is also changing attitudes and inspiring locals to preserve their natural treasures

smithsonian.com 
coral_goddess_and_snapper.jpg__800x600_q85_crop
Under the waters in Pemuteran, in Bali, this structure might be helping restore a coral reef. (Rani Morrow-Wuigk)

As you walk the beach in Pemuteran, a tiny fishing village on the northwest coast of Bali, Indonesia, be careful not to trip on the power cables snaking into the turquoise waves. At the other end of those cables are coral reefs that are thriving with a little help from a low-voltage electrical current.

These electrified reefs grow much faster, backers say. The process, known as Biorock, could help restore these vital ocean habitats at a critical time. Warming waters brought on by climate change threaten many of the world’s coral reefs, and huge swaths have bleached in the wake of the latest El Niño.

Skeptics note that there isn’t much research comparing Biorock to other restoration techniques. They agree, however, that what’s happening with the people of Pemuteran is as important as what’s going on with the coral.

Dynamite and cyanide fishing had devastated the reefs here. Their revival could not have succeeded without a change in attitude and the commitment of the people of Pemuteran to protect them.

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A Pemuteran resident assembles one of the Biorock reef restoration structures. (Rani Morrow-Wuigk)

Pemuteran is home to the world’s largest Biorock reef restoration project. It began in 2000, after a spike in destructive fishing methods had ravaged the reefs, collapsed fish stocks and ruined the nascent tourism industry.  A local scuba shop owner heard about the process and invited the inventors, Tom Goreau and Wolf Hilbertz, to try it out in the bay in front of his place.

Herman was one of the workers who built the first structure. (Like many Indonesians, he goes by just one name.) He was skeptical.

“How (are we) growing the coral ourselves?” he wondered. “What we know is, this belongs to god, or nature. How can we make it?”

A coral reef is actually a collection of tiny individuals called polyps. Each polyp lays down a layer of calcium carbonate beneath itself as it grows and divides, forming the reef’s skeleton. Biorock saves the polyps the trouble. When electrical current runs through steel under seawater, calcium carbonate forms on the surface. (The current is low enough that it won’t hurt the polyps, reef fish or divers.)

Hilbertz, an archihtect, patented the Biorock process in the 1970s as a way to build underwater structures. Coral grows on these structures extremely well. Polyps attached to Biorock take the energy they would have devoted to building calcium carbonate skeletons and apply it toward growing, or warding off diseases.

Hilbertz’s colleague Goreau is a marine scientist, and he put Biorock to work as a coral-restoration tool. The duo says that electrified reefs grow from two to six times faster than untreated reefs, and survive high temperatures and other stresses better.

Herman didn’t believe it would work. But, he says, he was “just a worker. Whatever the boss says, I do.”

So he and some other locals bought some heavy cables and a power supply. They welded some steel rebar into a mesh frame and carried it into the bay. They attached pieces of living coral broken off other reefs. They hooked it all up. And they waited.

Within days, minerals started to coat the metal bars. And the coral they attached to the frame started growing.

“I was surprised,” Herman says. “I said, damn! We did this!”

“We started taking care of it, like a garden,” he adds. “And we started to love it.”

Now, there are more than 70 Biorock reefs around Pemuteran, covering five acres of ocean floor.

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(Rani Morrow-Wuigk)

But experts are cautious about Biorock’s potential. “It certainly does appear to work,” says Tom Moore, who leads coral restoration work in the U.S. Caribbean for the National Oceanic and Atmospheric Administration.

However, he adds, “what we’ve been lacking, and what’s kept the scientific community from embracing it, is independent validation.” He notes that nearly all the studies about Biorock published in the scientific literature are authored by the inventors themselves.

And very little research compares growth rates or long-term fitness of Biorock reefs to those restored by other techniques. Moore’s group has focused on restoring endangered staghorn and elkhorn corals. A branch snipped off these types will grow its own branches, which themselves can be snipped and regrown.

He says they considered trying Biorock, but with the exponential expansion they were doing, “We were growing things plenty fast. Growing them a little faster wasn’t going to help us.”

Plus, the need for a constant power supply limits Biorock’s potential, he adds. But climate change is putting coral reefs in such dire straits that Biorock may get a closer look, Moore says.

The two endangered corals his group works on “are not the only two corals in the [Caribbean] system. They’re also not the only two corals listed under the Endangered Species Act. We’ve had the addition of a number of new corals in the last two years.” These slower-growing corals are harder to propagate.

“We’re actively looking for new techniques,” Moore adds. That includes Biorock. “I want to keep a very much open mind.”

But there’s one thing he’s sure about. “Regardless of my skepticism of whether Biorock is any better than any of the other techniques,” he says, “it’s engaging the community in restoration. It’s changing value sets. [That’s] absolutely critical.”

earthday_and_school_children_from_pemuteran.jpg__800x450_q85_crop_upscaleYayasan Karang Lestari Pemuteran, the local nonprofit that works with the creators of Biorock, also makes environmental education a priority. (Rani Morrow-Wuigk)

Pemuteran was one of Bali’s poorest villages. Many depend on the ocean for subsistence. The climate is too dry to grow rice, the national staple. Residents grow corn instead, but “only one time a year because we don’t get enough water,” says Komang Astika, a dive manager at Pemuteran’s Biorock Information Center, whose parents are farmers. “Of course it will not be enough,” he adds.

Chris Brown, a computer engineer, arrived in Pemuteran in 1992 in semi-retirement. He planned to, as he put it, trade in his pinstripe suit for a wetsuit and become a dive instructor.

There wasn’t much in Pemuteran back then. Brown says there were a couple good reefs offshore, “but also a lot of destruction going on, with dynamite fishing and using potassium cyanide to collect aquarium fish.” A splash of the poison will stun fish. But it kills many more, and it does long-lasting damage to the reef habitat.

When he spotted fishermen using dynamite or cyanide, he’d call the police. But that didn’t work too well at first, he says.

“In those days the police would come and hesitantly arrest the people, and the next day they’d be [released] because the local villagers would come and say, ‘that’s my family. You’ve got to release them or we’ll [protest].’”

But Brown spent years getting to know the people of Pemuteran. Over time, he says, they grew to trust him. He remembers a pivotal moment in the mid-1990s. The fisheries were collapsing, but the local fishermen didn’t understand why. Brown was sitting on the beach with some local fishermen, watching some underwater video Brown had just shot.

One scene showed a destroyed reef. It was “just coral rubble and a few tiny fish swimming around.” In the next scene, “there’s some really nice coral reefs and lots of fish. And I’m thinking, ‘Oh no, they’re going to go out and attack the areas of good coral because there’s good fish there.’”

That’s not what happened.

“One of the older guys actually said, ‘So, if there’s no coral, there’s no fish. If there’s good coral, there’s lots of fish.’ I said, ‘Yeah.’ And he said, ‘So we’d better protect the good coral because we need more fish.’

“Then I thought, ‘These people aren’t stupid, as many people were saying. They’re just educated differently.’”

pejalang.jpg__800x450_q85_crop_upscaleLocals formed a coast guard to protect their reefs after they started to understand the connection between healthy reefs and healthy fish. (Rani Morrow-Wuigk)

It wasn’t long before the people of Pemuteran would call the police on destructive fishermen.

But sometimes, Brown still took the heat.

Once, when locals called the police on cyanide fishers from a neighboring village, Brown says, people from that village “came back later with a big boat full of people from the other village wielding knives and everything and yelling, ‘Bakar, bakar!’ which means ‘burn, burn.’ They wanted to burn down my dive shop.”

But the locals defended Brown. “They confronted these other [fishermen] and said, ‘It wasn’t the foreigner who called the police. It was us, the fishermen from this village. We’re sick and tired of you guys coming in and destroying [the reefs].’”

That’s when local dive shop owner Yos Amerta started working with Biorock’s inventors. The turnaround was fast, dramatic and effective. As the coral grew, fish populations rebounded. And the electrified reefs drew curious tourists from around the world.

One survey found that “forty percent of tourists visiting Pemuteran were not only aware of village coral restoration efforts, but came to the area specifically to see the rejuvenated reefs,” according to the United Nations Development Program. The restoration work won UNDP’s Equator Prize in 2012, among other accolades.

Locals are working as dive leaders and boat drivers, and the new hotels and restaurants offer another market for the locals’ catch.

“Little by little, the economy is rising,” says the Biorock Center’s Astika. “[People] can buy a motorbike, [children] can go to school. Now, some local people already have hotels.”

Herman, who helped build the first Biorock structure, now is one of those local hotel owners. He says the growing tourism industry has helped drive a change in attitudes among the people in Pemuteran.

“Because they earn money from the environment, they will love it,” he says.

Original Article: Smithsonian.com