SEADOV FAQs

Q
If SEADOV is so good, why hasn't it been thought of before?

A
This is a question that can be asked of any invention. The particular backgrounds and interaction of experience of SEADOVs creators led logically to a powerful integration of several established technologies - which are not typically associated. This gave birth to SEADOV a purpose built or an oil industry vessel, moored with offshore industry technology, to support sustainable energy harvesting systems, to power reverse osmosis, and pump water to shore.

Q
Can SEADOV supply both potable water and electrical power to shore?

A
Yes, both power and water can be supplied to shore. This will be of particular use in developing world countries where both grid electricity and a clean water supply are lacking or are unreliable. Also remote coastal communities and mining or industrial projects could use power and water output supplied by SEADOV.

Q
Desalination of sea water requires a lot of energy. Wouldn't it be better to recycle treated effluent?

A
Effluent recycling is a viable choice in the absence of a SEADOV deployment. However treating recycled water to potable quality requires energy. Therefore unless non-polluting green energy is used, as is the case with SEADOV, there will be significant CO2 emissions.

Q
Isn't desalination more expensive than other options?

A
This depends on the location, the cost of energy and what the "other options" are, and the rigour of their costing processes. In some parts of the world desalination is already competitive with other available options although using expensive fossil fuel can change that equation. Moreover, with improvements in technology the capital and operating costs are continuing to decline.

Q
Doesn't desalinated water corrode pipes and taste bad?

A
Not if the pH (acidity or alkalinity) of the desalinated water is adjusted. This is the case with SEADOV .

Q
Are not dams a better option?

A
The environmental and social dislocation costs of dams are increasingly being recognized and due to climate change there is reduced runoff in many catchment areas; also evaporation is quite significant. In other words dams are becoming less cost-effective. SEADOV can also remove the need to raise dam walls which can incur high construction costs. Adding additional SEADOVs can also be a solution to increasing population growth.

Q
Why use green energy? Isn't wind more expensive and less reliable than coal and gas?

A
The relative cost of renewable energy depends on whether the costs of pollution and greenhouse effects are included in other energy sources. The cost of wind power is coming down all the time, having dropped by a factor of 5 in real terms since the early 1980s, while the cost of energy from fossil fuels is expected to rise in real terms. Sequestration of CO2 at fossil fuelled power stations, as is being seriously proposed, will further increase the cost of fossil fuelled energy. As to the reliability of potable water supply, wind turbines are very reliable machines and, although wind speed does fluctuate, with optimum sizing of the desalination plant for a given site, electrical energy in excess of the desalination plant's requirements during times of high wind speed will be fed ashore into the electrical grid to be matched by the drawing of electrical energy from the grid during times of low wind speed. Such electrical energy exchange is seamless and is well established technology.

Q
Wave and tidal current energy technologies are not yet established, are they?

A
The principles on which these technologies are based have been known since the 1970s and have been proven. Cheap oil and politics have prevented their commercial development until now, but both are developing rapidly. SEADOV is researching and monitoring developments in these technologies..

Q
Why not use nuclear power? It's obviously the answer.

A
Opinions are widely divided on the real costs of nuclear power (including government subsidies), which include radioactive waste disposal, decommissioning costs at end of life and danger of increasing amounts of fissionable material falling into the hands of terrorists and so on. We believe that there are safer options and SEADOV is pursuing them.

Q
How do SEADOV vessels cope with extreme winds and seas which occur during a cyclone?

A
SEADOV vessels will typically require very few personnel and in fact in certain circumstances can be un-manned and are moored using mooring systems which are designed and rated for cyclone and storm conditions. Because SEADOV vessels are ship shaped and are free to swing head-to-weather in extreme conditions, the mooring systems are relatively light. The mooring technology that SEADOV will use is well-established and has been utilised in the offshore oil and gas industry for several decades. Mooring systems will be specifically designed for each SEADOV site.

Q
Are SEADOV vessels a hazard to aircraft?

A
SEADOV vessels will not have particularly large air-drafts (height above waterline) but will be equipped with CAA compliant marker lights (typically red-flashing lights as placed upon high chimneys and towers). As fixed facilities which will be continuously present over many years SEADOV units will be marked upon nautical and aeronautical charts, and the data which these charts display includes the height of potential obstructions.

Q
Will the safety of amateur and professional fishers be compromised?

A
SEADOV vessels will be marked upon nautical and aeronautical charts and the data which these charts display will facilitate appropriate interaction with fishers. As a moored structure, each SEADOV unit will carry the standard (statutory) sound and light signals required. Fishers will not need to change their routine navigational practices because of the presence of a SEADOV vessel.

Q
Will sea-life safety be compromised?

A
No, it will be enhanced. It has also been observed that each vessel and its mooring will be beneficially colonised as ‘reef' by marine species endemic at each site, and each site will be a sanctuary.

Tidal turbines turn very slowly and sea life will easily avoid them. OWCs (Oscillating Wave Columns) are just chambers where waves surge up and down - not a problem for fish. Tests have shown that fish will move away from the pressure wave at the outside circumference of the OWC.

Q
How is salt concentration and disposal dealt with?

A
The solution is dilution. Basically the salty-water by-product of the on-board RO (Reverse Osmosis) plant is about twice as concentrated as sea water. SEADOV will use ultra-filtration for pre-treatment of feedwater rather than the biocides used in some RO plants to combat bio fouling of membranes, so the "reject brine" is simply concentrated seawater. SEADOV vessels will be located several kilometers offshore and the expelled water from the RO plant will be discharged through diffusers at several locations around the hull high in the water column, in a way that ensures it is mixed and diluted to the point where there is no significant local increase in salinity. Sea currents will quickly mix and dilute the higher salinity reject water. Also the SEADOV disposal of salt water is located in the upper-water levels, which facilitates dispersal.

SEADOV's waste salt disposal is inherently more efficient than that of shore-based desalination plants, which typically dump waste brine at the sea-bed, where the more dense brine may tend to accumulate. In any event SEADOV is keen for the disposal of salt water waste to be as environmentally sound as SEADOV itself.

Q
How much electrical power will be generated on SEADOV on a given day?

A
The electrical energy generated on board a SEADOV vessel will vary from site to site. For example an average of around 78,000 kWh per day (3.25 MW) for the Gold Coast, Australia and around 144,000 kWh per day (6 MW) for Perth, Australia is predicted.

Q
Does pipe to shore compromise boat safety?

A
As fixed facilities, which will be continuously present over many years, SEADOV vessels will be marked upon nautical charts and, as is the case with all sea-bed pipelines, power lines and telephone cables, the sea-bed in near proximity will be marked on charts to indicate the prohibition of anchoring. It is anticipated that this will be the only interaction of boats with the pipe-line.

Q
Is the pipe to shore vulnerable?

A
The ship to shore pipeline will be stabilized and ballasted to ensure it remains as-laid on the sea-bed, and is secure from tides, current and heavy weather. The pipeline will become part of the sea-bed's ecology with very little impact after the initial lay. Whilst the pipeline will be largely exposed and somewhat vulnerable to damage from illegal anchoring by vessels, such damage cannot cause a polluting spill or hazardous event as would be the case with an exposed oil or gas pipe-line. Nevertheless where site conditions require it additional protection can be provided.

Q
Are scuba divers safe?

A
It is not anticipated that SEADOV units will be sited such that recreational divers will be attracted to dive on SEADOV assets. In any event SEADOV vessels will be restricted areas and private property - and will be marked accordingly and remotely monitored by camera surveillance. SEADOV maintenance will require diving operations from time-to-time and we anticipate that marine biologists may also take the opportunity to utilise our facilities, but these operations will be conducted by professional and qualified divers, and planned in concert with the SEADOV Company.

Q
Will SEADOV water be an expensive waste when rainfall causes the dams to overflow?

A
No, the cost of SEADOV water is the cost of certainty of supply in an uncertain environment. Practically speaking, this would provide opportunities for system maintenance during rare overflow events. Also SEADOV units can be relocated to areas of need.

Q
What sort of contract would SEADOV seek with the Government?

A
A long-term contract to supply water at an agreed price, CPI index adjusted and viable for Government and SEADOV …

Q
Why should the Government risk a long term contract with an untried technology?

A
SEADOV does not employ any untried technology; all SEADOV technologies are tried and proven:
  • offshore mooring technology
  • wind-farm technology
  • tidal turbine technology
  • wave chamber technology
  • reverse osmosis technology
  • pipe-lay & pumping technology
  • power transmission technology

Q
Why should Government risk a long-term contract with an untried company?

A
SEADOV Pty. Ltd. is the research and development partner who with established and significant corporations within associated industries including financial investment groups will JV at a given site project....subject to viability. Importantly does not plan to sell its vessel for others to operate, rather it will sell its metered water and or power on a metered basis, therefore removing financial risk exposure for Government or Industry clients.

Q
If we use sustainable energy from wind farms to power onshore RO plants, why is SEADOV better?

A
We would like to see both, and the more renewable energy we use instead of fossil fuels, the better for our planet. However SEADOV
  • has no transmission losses - so it uses the electricity it makes far more efficiently
  • does not take up valuable sea-side land, or create an eye-sore
  • will not impact vulnerable bird species
  • will not impact agricultural production
  • will be sited in optimal energy environments and accesses multiple harvestable renewable energy forms, not just wind
  • Will recycle oil tanker hulls where available, to make sustainable energy. ecycle oil-tankers to make sustainable energy

Q
Won't plankton, fish etc get sucked into Seadov with feedwater?

A
Fish are not at risk because the flow into the intakes is slow enough that they can avoid them. Some plankton will be sucked in, but the City of Santa Cruz Water Department an Soquel Creek Water District... found that impingement and entrainment impacts were “less than significant” (http://pacinst.org/wp-content/uploads/2013/12/desal-marine-imapcts-full-report.pdf, SCWD2 2013). That is, the agency estimated impacts would occur, but that they do not rise to the level that requires any mitigation under California’s environmental laws. One reason for the “less than significant” designation is that no endangered or threatened species were found during sampling. Seadov impacts will be less than those for major onshore desalination plants because
  1. Seadov is smaller and will take in much less feedwater
  2. the Seadov intakes will be in areas of low biological productivity, in deep waters
  3. intakes will be low-velocity, allowing some organisms to swim out of the current
  4. we can temporarily reduce pumping or intake velocity during critical periods for
  5. There are also several technological measures to reduce impingement and/or outside of bays and estuaries;
marine organisms, such as during spawning or important larval stages. entrainment from surface intakes. Physical barriers, e.g., mesh or wedgewire screens, block fish passage into the desalination plant and may be coupled with some sort of fish collection and return system. Behavioral deterrents, e.g. strobe lights or velocity caps, provide a signal to keep fish and other organisms away from the intake area or prevent them from crossing a threshold where they may be impinged.

Q
Won't the discharge brine contaminate the surrounding ocean?

A
The "brine" is basically seawater with about twice the concentration of salt and very small concentrations of chemicals, which can be easily diluted by discharging though diffusers, which mix the discharge water with surrounding seawater to the point that they are virtually undetectable. Most desalination plants discharge brine near the bottom of the water column where there is little wave action to promote mixing, and being more dense than the surrounding sea water it tends to stay at the bottom. But Seadov is located in an energetic wave climate and diffusers are near the surface, so mixing is enhanced as the brine sinks through the turbulent water column. Experience with existing desalination plants suggests that this is not an issue. For example the Perth (Australia) Desalination Plant began operating 2006. A 2008 report states that the effluent from the plant is so highly diluted that it does not have a measurable impact on stratification or dissolved oxygen(http://epa.wa.gov.au/EPADocLib/2955_Rep1327PerthDesals4625509.pdf).

Q
Will sea birds be killed by the wind turbine blades?

A
A new report by a leading bird research institute in the U.K. found that over 99 percent of seabirds were likely to alter their flight paths in order to avoid collision with offshore wind farms (http://thinkprogress.org/climate/2014/12/18/3605149/birds-offshore-wind-turbines-2changing-course). And Royal Society for the Protection of Birds (RSPB) conservation director, Martin Harper, says a large body of scientific evidence shows "appropriately located windfarms have negligible impacts" on bird populations. http://www.carbonbrief.org/blog/2013/04/wind-farms-and-birds. So, while we can't guarantee absolutely no bird kills, we're confident that they'll be negligible compared to the millions killed by buildings, cars, powerlines, cats etc.

Q
Will fish be killed by the wave energy converters?

A
No. The sea water simply flows gently into and out of the oscillating water columns. There are no sharp blades or anything else that could harm fish.

Q
Would SEADOV be affected by a Tsunami?

A
only a slight swell usually of the order of 30 cm (12 in) above the normal sea surface. When they reach land the wave height increases dramatically as the base of the wave pushes the water column above it upwards." So SEADOV will be unaffected as it will typically be located about 10 miles (16 km) off shore, while shoreline structures may suffer serious damage.