FAQ

1. Aren’t your projects just dams?

No. Our projects are not dams. Dams are structures that impound water, creating a permanent reservoir. Halcyon Tidal Power Plants (TPPs) preserve the full flow of the tides in and out of the basin during each tide. The same volume of water enters and leaves the basin as it would if the Halcyon TPP were not there at all. This occurs twice each day, with two high and two low tides, just as it would in the absence of the project. Because Halcyon TPPs do not affect the volume of water or the flow rate in and out of the basin, the operating cycle has been named the ‘Free Flow Cycle’. It is the only tidal power cycle that preserves the full flow of the tides. All other tidal energy extraction technologies, including hydrokinetic devices, reduce tidal flows and damage the intertidal zone.

Another means of distinguishing a Halcyon TPP from a dam is the location of the ‘basin’. For a dam, there is no question that the ‘basin’ is the area behind, or upstream of, the dam. For a Halcyon TPP, the ‘basin’ could be readily described as either side of the enclosure.

Halcyon’s Free Flow Cycle must be clearly distinguished from generating cycles that have been utilized or proposed in the past, because it represents a fundamental and environmentally sound departure from former tidal range projects. Projects such as La Rance in France and Annapolis-Royal in Nova Scotia permanently raise the water level in the basin, and in that limited sense, are dams. Such projects reduce the amount and rate of water flow, permanently submerging ecologically essential intertidal zones, and increasing water residence time causing the accumulation of sediments. By preserving the full volume and rate of flow, a Halcyon TPP maintains the natural rise and fall of the tides and protects intertidal habitats. Because Halcyon TPPs do not change the amount or rate of flow, they cause no sedimentation. The maintenance of natural residence time also prevents a decrease in the flushing rate of nitrates and other potentially harmful substances.

Halcyon TPPs neither operate (as noted above) nor appear like a dam. They are designed to appear as a narrow, 3 meter wide bridge which rises only 5 meters (15 ft) above the mean water level with the bulk of the structure remaining permanently submerged. Even the exposed portion of the structure will be difficult to see at any significant distance. On the other hand, if one views the Hoover Dam at the border of Arizona and Nevada, one sees a permanent basin, Lake Mead (the largest reservoir in the US), on one side and a massive wall of concrete on the other. There is no ‘man-made permanent basin’ created by a Halcyon TPP. As noted earlier, the ‘basin’ of a Halcyon TPP could be either side of the enclosure, and since there is no change to the hydrology of tidal flows into or out of the enclosure, no ‘man-made permanent basin’ representative of a dam is created.

2. Why not use an array of hydrokinetic turbines anchored to the seafloor to harness tidal energy?

Tidal range facilities (similar in form to Halcyon TPPs) have a proven operational track record, whereas sea floor-anchored tidal power facilities (also called in-stream, hydrokinetic or tidal current) do not, and are all in the experimental stage. Tidal range facilities have also proven to be economically viable over the vast majority of their useful lives (the La Rance Facility is reputed to produce energy at less than $.03/kWh), while current energy prices in support of various hydrokinetic facilities has ranged between $.22/kWh and $.65/kWh, with the expectation that costs will somehow and at some point approach current market energy prices of $.10/kWh. Historically there has been substantial ratepayer resistance to any significant increase in power prices, and we fully expect this to continue in response to expensive hydrokinetic projects.

Halcyon TPPs will provide power at competitive rates over the initial financing period (20-30 years), and for the balance of their 120 year useful lives, they will produce power at rates below fossil fuel, nuclear or any other renewable power plants! In contrast, the lifetime of hydrokinetic devices is not likely to be much beyond 20-30 years (their expected initial financing period) and therefore an array of these devices are not likely to provide the long-term low-cost energy prices of our projects.

There are also significant environmental advantages which Halcyon TPPs have over hydrokinetic facilities, including maintenance of flow rate, reduction of sedimentation incidence and the known vs unknown effects on fishes, cetaceans, other marine life, commercial fishing and navigation.

Of critical importance to fighting climate change is the “ready to go” status of Halcyon TPPs. Hydrokinetic devices, like many other renewable technologies, are still in development. Not only may their success be ‘late to the game’, it is also less than assured. For example, Sustainable Development Technology Canada – a Canadian Federal Government source of development funding – has provided development funding for 5 hydrokinetic projects, all of which have failed to produce a successful commercial application). The effects of climate change are rising at an alarming rate (some say we have already reached the ‘tipping point’, from which there is no return to the status quo) and will not wait for the deployment of future technologies. Halcyon can make a significant and immediate contribution to slowing down the destructive effects of greenhouse gas emissions because it is large scale, low cost, and ready to go now.

3. How will fish and other marine life enter and exit the basin?

There are three types of entry and exit points for marine life distributed across the entire span of the structure: the turbines, the sluice gates, and over the structure when submerged by the highest 20% of tides, with the default passage for fish through the turbines themselves. The Alstom bulb turbines selected for Halcyon TPPs have a strong track record for low fish mortality [see here for more detail], but we have modified them even further to improve fish survival. These modifications include low rotational speed to prevent sudden pressure gradient changes detrimental to some fish bladders, reduction in the number of blades, and thickening the leading edge of the blades to 10-15 centimeters to reduce damage to fishes from physical strikes.

The result is that fish slide off the rounded profile of the blade rather than being sliced or injured by it. Smaller diameter (3.2 m) bulb turbines were selected to further reduce peripheral blade strike velocities. The need for any further measures would be informed by the studies to be conducted at the site as part of the permitting process, in particular to determine the fish species present and their size. Should problems emerge for large fish, screens can be deployed preventing entrainment into the turbines. Large fish would still have access to the basin through the spillways over the enclosure and turbine caissons, as well as over the top of the structure when submerged by the highest tides, as noted above.

Previous experience has shown that marine mammals are intelligent and sufficiently aware of their environment to avoid turbines. However, appropriate screening of the turbines to prevent entrainment works as well for mammals as fishes. Again, mammals would still have access over spillways, which are large enough to accommodate all but the very largest cetaceans.

It should be further noted that Halcyon TPPs will be sited so that they do not enclose major spawning rivers or block migratory routes.

4. Won’t your projects harm the intertidal zone and/or create sedimentation build-up in the basin?

No. Sediment accumulation in a typical basin is due primarily to changes to the rate and volume of water flow. Sediment is naturally suspended in the water, and if water is unnaturally stationary for extended periods (so-called ‘increased residence time’), such as behind a hydroelectric dam, the sediment falls and collects on the bottom of the basin. Accumulation of sediment in a basin reduces the water volume of the basin over time, which reduces the power output of hydroelectric power plants.

Our facilities replicate the natural ebb and flow of the tides using our Free Flow Cycle – two-way generation plus pumping. Since the enclosure prevents natural unimpeded tidal flows, pumping of seawater into and out of the basin is required in order to replicate the natural tidal flows. The basin is flushed and refilled as it would be without our project, which means that no net sedimentation will occur. Halcyon’s Free Flow Cycle fully preserves the natural amplitude of the tides. The results is that the intertidal zones are exposed and submerged to their natural boundaries on each tidal cycle. No intertidal habitat is lost. The Free Flow Cycle was validated and modeled in detail by Alstom Power.

5. How do you know that it will function as described?

Our turbine technology has been modeled in collaboration with Alstom Power using the same software programs they use to accurately model hydroelectric projects all over the world. Our construction technology was developed in collaboration with MEG Consulting, a British Columbia based geotechnical engineering firm, and was favorably reviewed by the UK Department of Energy and Climate Change and engineering firm Parsons Brinkerhoff in the Severn Tidal Power Consultation.

Tidal range power itself is not a new concept, but our technology represents a significant technological advancement in the space. Six tidal range power plants have been built by other companies and governments over the past 40 years, including Annapolis Royal in Nova Scotia. All of these facilities have operated successfully, albeit with harmful environmental effects. Halcyon has patented construction and operating methodologies that have significantly advanced the capabilities of tidal range facilities, reducing costs by 50% and avoiding harm to the environment. Our patented construction methodology has been adapted from methods perfected in offshore oil and gas platforms over the past decade and the operating methodology has been developed with assistance from Alstom Power, the largest hydroelectric turbine manufacturer in the world.

6. How will watercraft enter and leave the basin?

All Halcyon TPPs will have locks manned 24 hours a day for the use of powered vessels typically utilizing the basin for marine harvest, recreation or mooring. 20,000 boats per year pass through the boat locks at the La Rance facility. Special provision will be made for very small watercraft, kayaks, and canoes depending on need.

7. Won’t there be negative tourism impacts?

No. On the contrary, according to its owner, Nova Scotia Power, visitors to the Annapolis Royal tidal range facility approach 40,000 annually. EDF reports 70,000 visitors to the La Rance tidal range facility in France each year.

8. What is the potential build-out of these projects around the world?

Tidal range projects that have been designed or considered in detail to date would produce approximately 10% of the current world power consumption, if they had all been built. However, with the high cost of construction, these projects were winnowed down to locations where relatively short barrages could be constructed. Halcyon TPP lagoons can be built at length, at depth and along any shoreline with sufficiently high tides, greatly expanding this tidal energy resource.

We estimate that with full utilization of potential sites on five continents within the next several decades, closer to 20% of the world’s electrical demand could be met! Halcyon technology makes available many sites that were previously examined, but rejected, due to high costs and/or environmental concerns. Halcyon technology resolves both of these issues. See here for an interactive map of potential sites around the world.

9. What regulatory bodies, government agencies, local groups and other interested parties have you been in contact or consulted with concerning your projects through 2013?

Pennamaquan TPP – We have been in contact and consulted with, among others, the Maine Department of Environmental Protection; Fish and Wildlife; Marine Resources; Public Utilities Commission; Joint Standing [Legislative] Committee on Energy, Technology and Utilities and its Chairmen; Washington County State Senator Burns; Town of Pembroke State Representative Lockman; Governor LePage and the Executive Branch Energy Director; the Selectmen of the Town of Pembroke; local residents of Pembroke; Maine Lobsterman’s Association; Cianbro; Federal Energy Regulatory Commission; U.S. Fish & Game; U.S. Coast Guard; and Army Corps of Engineers. We have also attempted to contact the Pleasant Point Passamaquoddy Tribe.

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