Mit ClimateColab Proposals Portlet Mit ClimateColab Proposals Portlet

This Proposal was reopen here from Energy Supply 2016

Pitch

A revolutionary new way to reduce GHG emissions and provide an abundant, reliable source of renewable energy.

Description

Summary

  

    

The Tidal Energy Power Plant typically will be 1 - 2 kilometers in size and usually will be built in areas that have a water depth of between 20 - 50 meters. The plant can be constructed either at shore or offshore and will be funnel-shaped when viewed from above. The walls will rise above the high tide mark and the open end will face the incoming tide, which ideally would have a range of over 2 meters.

It can be likened to a wave pool with constant incoming wave pressure. If the wave pool angled inwards, it would be expected that the water would be higher at the triangular point as opposed to the same point in a rectangular pool.

The flow of water that enters the plant will rise above the surrounding water as it is funneled into the area of the turbines. The water will not be 'captured', and then released when it is low tide. It will actually be a continuous flow of water that enters and exits the turbines as the tide is coming in. It is the height differential (pressure) between the water inside the structure and the water outside the structure that results in the water flowing through turbines to generate electricity and is then released back into the surrounding water.

Constructing walls in the opposite direction and the use of gates will allow both the flooding and ebbing tides to be harnessed. 

Although the concept may appear similar to other methods currently in use such as tidal barrages and instream turbines, it is in fact vastly different due to its' unique design. The power that will be harnessed is an untapped resource.

 

* The sheer volume of water that can be moved during a tidal cycle is immense. For example; at the 80 kilometer wide mouth to the Bay of Fundy in Canada, 160 billion tonnes of seawater (equivalent to 160 billion cubic meters/ 160 cubic kilometers) flows in and out of the bay during each tidal cycle.[1]

* To understand the concept better, please watch the PBS video which can help explain the physics.[2]

Category of the action

Reducing emissions from electric power sector.

What actions do you propose?

The first action to be taken is to prove whether the concept is viable.

An important question that needs to be answered is - How fast does the tide travel and do the facts support this?

Accepted science states that it is possible to determine the speed of an object if the time and distance the object has traveled is known. Tidal speed can be calculated by comparing the time of the high tide as it crests at different locations that are part of the same tidal system.

Two areas that are known to have high tidal ranges are (A) the Bay of Fundy in Canada and (B) the northern coast of France along the English Channel.

 

                                                                    BAY OF FUNDY

 

         

 


This map illustrates the distance between the settlements of Parkers Cove, Nova Scotia and Baxters Harbour, Nova Scotia. The distance by road is 114 kilometers. A more direct route by sea is approximately 100 kilometers. 

 

                                TIDE TABLES FOR PARKERS COVE AND BAXTERS HARBOUR

 

     

 

 

These tide tables from tides.gc.ca show the time of both high and low tide for these two locations. These are the predictions; actual results may vary slightly. Date of December 20, 2016.

The tide table for Parkers Cove shows the first high tide of the day arriving at 04:05 with a high tide of 8.2 meters.

The tide table for Baxters Harbour shows the first high tide of the day arriving 36 minutes later at 04:41 with a high tide of 11.3 meters.

With a distance of approximately 100 kilometers between these two locations and the tide traversing this distance in 36 minutes, the tide can be calculated to be traveling at an average speed of 166 kilometers per hour (103 mph).

60 (minutes) ÷ 36 (minutes) = 1.66

100 (kilometers) x 1.66 = 166 km/hr

 

* Due to friction, the tide which can travel 700 km/hr in the deep ocean, will slow dramatically as it enters shallower water and nears the shore.[3]

* Parkers Cove has a tidal range of over 5 meters, but it is not the top 5 meters of the Bay of Fundy traveling 166 km/hr; rather it is a net value of 5 meters inside the total depth. It could be compared to a tsunami wave that quickly travels across the ocean but only causes a small ripple as it passes by in the ocean. This same principle also applies to example (B).

* The water coming ashore would not be traveling 166 km/hr, but is filling in along the way. The main tidal force/current is in the deeper water.

                                                               

                                             ENGLISH CHANNEL - COAST OF FRANCE

 

                                                                                                                                                                                                                 

                                                                                                                                                                          

This map illustrates the distance between the towns of Fecamp and Le Treport in France. The distance by road is 94 kilometers. A more direct route by sea is approximately 75 kilometers.

 

                                     TIDE TABLES FOR FECAMP AND LE TREPORT

        

      

 

The tide tables are from tides4fishing.com/fr  Date of July 14, 2016.

The tide table for Fecamp shows the first high tide of the day arriving at 07:45. The tide table for Le Treport shows the first high tide of the day arriving at 08:10.

With an approximate distance of 75 kilometers between these two towns and the tide traversing this distance in 25 minutes, it can be calculated that the tide is traveling at an average speed of 180 kilometers per hour (111 mph).

60 (minutes) ÷ 25 (minutes) = 2.4

75 (kilometers) x 2.4 = 180 km/hr                                                              

                                

* Even 10 kilometers off the coast of France at these two locations, the water is less than 50 meters deep.

 

                                                           AMPHIDROMIC SYSTEM

A second line of reasoning can be found by examining Amphidromic system maps.[4] [5]

Orbiting satellites such as the original TOPEX/Poseidon (now decommissioned) and the recently launched Jason-3, are equipped with sophisticated instruments which can make highly detailed measurements of sea surface height, measured to within centimeters.[6]

 

 

Amphidromic points, also known as tidal nodes are a type of wave pattern. They have been mapped and help illustrate how tidal forces act upon large bodies of water.

There are about twelve major cells worldwide along with a number of smaller cells. In the middle of each cell is a node located near the center of an ocean basin, termed an amphidromic point, a no-tide point in the ocean around which the tidal crests and troughs rotate through each tidal cycle. Owing to the shape and location of landmasses surrounding the ocean basins, the tidal crests and troughs cancel each other at these points.

The tidal wave crests sweep around each Amphidromic point like spokes on a bicycle wheel.

There are 12 lines called cotidal lines that surround each amphidromic point and the crests or troughs will lead or lag by 1 hour and 2 minutes between each line. The total tidal cycle is 12 hours and 25 minutes, which is half a lunar day. The further away from the Amphidromic point, the higher the tide level becomes as can be seen by examining the NASA map.

In areas such as the English Channel and the Bay of Fundy, the tidal system will break off from the major Amphidromic systems and become smaller subsystems, but will still follow the tidal cycle.

 

                      ENGLISH CHANNEL AND THE NORTH SEA

 


The cotidal lines are still 1 hour and 2 minutes apart as the tide progresses up the English Channel.

 

                                               BAY OF FUNDY               

                           

 

In this diagram, the cotidal lines are shown in half hour increments as the tide progresses up the bay. The tidal range at various locations is shown as the dashed line. Note how the incoming tide is being funneled.

By calculating the time and distance between the 3 and 3.5 hour mark, it can be seen that the tide is traveling at an average speed of 180 km/hr.

 

                                                            CONCLUSION

A detailed examination of both the tide tables and the Amphidromic system reveals that in certain areas, the tide travels at speeds of well over 100 km/hr. 

 

 

        EXPECTED FLOW AND POWER OUTPUT FOR THE TIDAL ENERGY POWER PLANT                            

Expected peak flow from a 1 kilometer plant with a 4 meter tidal range and being in 30 meters deep water. Tidal speed of 150 km/hr (41.6 meters/sec.)  

1000 meters (1 km) x 4 meters (tide) x 41.6 (m/s) = 166,400 cubic meters per second

 

Power output formula [7]

The theoretically power available from falling water can be expressed as

   Pth = p q g h

   where

   Pth = power theoretically available (W)

   p = density (kg/m^3) (~1000 kg/m^3 for water)

   q = water flow (m^3/s)

   g = acceleration of gravity (9.81 m/s^2)

   h = falling height, head (m)

 

Example - Hydropower

The theoretically power available from a flow of 1 m^3/s water falling 100 m can be calculated as

    P = (1000 kg/m^3) (1 m^3/s) (9.81 m/s^2) (100 m)

       = 981 000 W

       = 981 KW

 

Efficiency

Due to energy loss the practically available power will be less than the theoretically power. Practically available power can be expressed as

   Pa = u p q g h

   where

   Pa = power available (W)

   u = efficiency  (in general in the range .75 to .95)

 

Tidal Energy Power Plant

    P = 1000 (kg/m^3) x 166,400 (m^3/s) x 9.81 (m/s^2) x 36 (m)

       = 58,765,824,000 W

       = 58.7  GW

 

  Pa = .24 (efficiency) x 1000 (kg/m^3) x 166,400 (m^3/s) x 9.81 (m/s^2) x 36 (m)

       = 14,103,797,760 W

       = 14.1 GW

 

* Important notes: The head created in this engineered structure is expected to exceed the 15 meter tidal range seen in the Minas Basin, which is located at the end of the Bay of Fundy. The funneled flow of water inside the plant would not have to overcome 200 kilometers of friction coming from the bottom of the bay, nor from the water in the bay itself.

With sufficient pressure (ie. tidal speed) a 1000 meter wide x 4 meter vertical (tide) flow at the entrance would be funneled through a 100 meter wide opening, leading to the containment area where the turbines are located. More study is required, but based on the preliminary findings of the expected flow and total volume, a head of approximately 36 meters (40 meters - 4 meters) may be produced. Calculating more precise figures will still have to take into account friction and other dynamics. 

* The speed of the water entering the containment area may have to be reduced in order to protect the integrity of the structure. This can be accomplished by expanding the entrance to the containment area from 100 meters to 200 meters.

* The efficiency rating of 24% is based on the Sihwa Lake Tidal Power Station in South Korea that only generates power on the tidal inflows.[8] 

 

FINAL PROJECTED TOTALS FOR POWER OUTPUT

      Power available = 14.1 GW

      Annual hours      = 8760 (24 x 365)

      Annual output   = 123.5 TWh (123,516 GWh)

 

 

Note: A Q&A session for this section has been included as questions may arise as to the scale of this project. 

Q... Who would allow a 1 kilometer structure to be built out into the ocean and would this be a navigation hazard?

A... 1 kilometer may sound like a lot, but the proposed Swansea tidal lagoon will have a wall looping out into the bay for a total length of 9.5 kilometers.[9] Also, the Navy Pier in Chicago extends 1 kilometer into Lake Michigan and serves as both a tourist attraction and boat dock.

To help with navigation around the structure, pillars with warning lights could be built around the perimeter of the plant.

 

Q... I thought that once you go past about 100 meters off the shore that the ocean gets very deep?

A... It depends on the specific location. Ocean depths can vary greatly. For example; off the eastern coast of the United States, the continental shelf can extend over 50 kilometers from shore before it gets really deep. Even at 20 kilometers off the coast of Virginia, the ocean is less than 30 meters deep. Conversely, at 5 kilometers off the coast of Southeast Florida, the ocean can be over 100 meters deep in places. 

Using a website such as arcgis.com with their ocean basemap can help with finding suitable locations for the Tidal Energy Power Plant.

 

Q... I find it difficult to follow the math and reasoning you put forth for the tide tables and Amphidromic system. Is there a simpler way to explain why you think the tide is traveling so fast?

A... Another line of reasoning that may be easier to follow involves looking at a map of the Bay of Fundy that shows the continental shelf.                                                                                                                                                                                                             

 

- People will accept that the tide flows in and out of the Bay of Fundy from the Atlantic Ocean twice a day or actually twice in a lunar day which is 24 hours and 50 minutes.

- If a measurement is done on a map from the edge of the continental shelf to the far shore of the Minas Basin which is at the end of the Bay of Fundy; it is over 400 kilometers.

- If the tide is only traveling 20 km/hr (12 mph) as many people would expect, a quick calculation will show that it would take over 20 hours for the tide to travel just one way. Not even close to the two full tidal cycles.

- So, it is obvious that the tide is traveling at an average speed much greater than 20 km/hr.

 

Q... Can this concept be tested on a small scale to prove that it works and how much do you think that would cost?

A... It may be possible to conduct a real world test in 20 meters deep water, with two temporary seawalls 300 meters in length. The estimated cost is $15 million dollars.[9][10]

Who will take these actions?

 

Ultimately, it will be up to local communities to decide where these plants are located.

Three possible scenarios that may or may not occur:

  1. The inhabitants of New Brunswick and Nova Scotia may decide that they only want 1 plant constructed on each side of the Bay of Fundy, due to possible environmental concerns.
  2. The inhabitants of Massachusetts, New Hampshire and Maine may not want any plants located within 10 kilometers of the shore because of esthetic concerns, but may allow a half dozen plants to be built out on the Georges Bank, which is located 200 kilometers offshore. The water in this area is shallow and the tide can reach 1 meter high.
  3. The people of France and England may decide that upwards of 10 plants could be located along the length of the English Channel, as these 10 plants could meet the electricity requirements for all of Western Europe.

 

                                                TESTING AND IMPLEMENTATION


For the test - initial private investors who provide funding along with the collaboration of a university providing scientific oversight.

For full scale implementation - private investors along with large utilities.

Where will these actions be taken?

For the test; although the walls will be temporary, it may be best to perform the test in an uninhabited area that is easily accessible for testing purposes and the taking on of needed equipment and supplies.  

A preliminary study indicates that there are a number of areas along the ocean coasts of the world that have tides exceeding 1 meter combined with tidal speeds approaching 100 km/hr.

Permanent structures could be built at any suitable location after environmental assessments have been completed.                            

How much will emissions be reduced or sequestered vs. business as usual levels?

Assuming current trends and the full scale implementation of the Tidal Energy Power Plant, green house gas emissions could be below 2015 levels by 2035.

Within 20 years, it could be expected that 25% of existing coal plants worldwide would be retired. A key to this figure being reached would be building plants capable of capturing both the flooding and ebbing tides to smooth out the load. The strategic placement of plants in different locations will also help minimize the effects of slack tide periods. Another important factor would be the introduction of energy storage, which would likely include pumped water storage, hydrogen production and synthetic fuel production. It could also be expected that a large number of gasoline powered cars worldwide would be replaced by vehicles using batteries or hydrogen fuel cells.

What are other key benefits?

The technology used, (turbines, construction methods etc.), is basically 'off the shelf'.

Visible pollution (smog) should dramatically decrease over time in areas that have access to the energy produced. 

What are the proposal’s costs?

 

                                          BREAKDOWN OF EXPECTED COSTS

  $2 billion initial capital cost.

  $6 million annual payroll - 40 employees @ $150,000 per employee.

  $15 million per year for other operational expenses and maintenance.

 

* This is based on a 1 km size plant built offshore and does not include any additional licensing costs. Building facilities for hydrogen and synthetic fuel production will add to this cost.

* The construction cost estimate is based on the Rance Tidal Power Station in France, which when adjusted for inflation (2009) cost $760 million.[11] The Sihwa Lake Tidal Power Station built in 2011, cost $293 million excluding the seawall.

* Additional transmission costs due to the plant being offshore would appear to be minimal as the plant would generally be within 5 - 10 kilometers of the shore. Any additional costs for the maintenance of the transmission lines to shore can be included in the general maintenance costs of the plant.

                                       LEVELIZED COST OF ELECTRICITY  

  T.E.P.P. (est.)              ---  16

  Wind (onshore)         ---  74

  Wind (offshore)         ---  197

  Solar PV                    ---  125

  Solar thermal            ---  240

  Advanced Nuclear   ---  95

  Conventional Coal   ---  95

  Hydro                        ---  84

  Natural Gas A.C.C.   ---  73              

 

* Projected average of the LCOE in the U.S. by 2020 (as of 2015) in dollars per MWh. Based on 30 years. Cost of capital 6.1%. Source - Wikipedia

 

                                                        ENVIRONMENTAL IMPACT

The Tidal Energy Power Plant is expected to be a low impact design when it comes to the environment. With the installation of nets and other deterrents, migrating mammals and large fish should be protected. Environmental assessments would still need to be completed in order to identify any other areas of concern including downstream effects.

Time line

Testing phase - 1 year, (planning, construction and analysis) 

Construction of the first plant along with the associated infrastructure - 5 years

Related proposals

N/A

 

References

[1] Bay of Fundy tides http://fundyforce.ca/renewable-and-predictable/the-bay-of-fundy   

- More specifically, the density of surface seawater ranges from about 1020 to 1029 kg/m^3 depending on the temperature and salinity. With the variability in tidal flows throughout the year and for mathematical simplicity; 1 cubic meter of seawater in this study will be considered to have a weight of 1000 kilograms (1 metric tonne).

[2] PBS digital studios. What physics teachers get wrong about tides! Space time - YouTube video http://m.youtube.com/watch?v=pwChk4S99i4     

[3] Waterencyclopedia - Deep ocean tidal speed; scroll down to the subheading - Landforms and Tides http://waterencyclopedia.com/St-Ts/Tides.html  

[4] Wikipedia - Amphidromic system  https://en.wikipedia.org/wiki/Amphidromic_point

[5] University of Southampton - Amphidromic system                                   http://moocs.southampton.ac.uk/oceans/2014/11/09/Amphidromic-points-tidal-spiders-in-a-real-world

[6] Jason-3  https://www.nesdis.noaa.gov/jason-3/index.html

[7] Engineeringtoolbox www.engineeringtoolbox.com/hydropower-d_1359.html An online calculator is available on this webpage.

[8] Sihwa Lake Tidal Power Station http://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station

[9] Video link for the use of geotubes in Swansea Bay, Wales  http://www.tidallagoonswanseabay.com/the-project/film/107

[10] Dredging in Ocean City, New Jersey http://ocnjdaily.com/pipeline-in-place-for-north-end-dredging-in-ocean-city

[11] Rance Tidal Power Station http://www.british-hydro.org/downloads/La%20Rance-BHA-Oct%202009.pdf and http://appropedia.org/Rance_Tidal_Power_Station

 

Diagrams

- Bay of Fundy and English Channel overview maps courtesy of Bing Maps

- Directional maps of the Bay of Fundy and English Channel courtesy of Google Maps

- Credit for the world-view Amphidromic system map

        NASA - Goddard Space Flight Center

        Jet Propulsion Laboratory

        Scientific Visualization Studio

        Television Production NASA/GSFC

- Credit for the article which includes the Bay of Fundy diagram - Amphidromic Points: tidal spiders in a real world.

        Christian Florindo - Lopez, University of Southampton                                                                         See the article for specific source information

- North Sea and English Channel Amphidromic System map courtesy of Wikipedia

- Bay of Fundy map showing the continental shelf courtesy of Arcgis.com

 

* Note that the references are presented in an informal manner.

* A patent application has been filed regarding this project and includes further details that are not covered in this proposal.

Thumbs up 3 supporters Support Proposal
Proposal Summary
Tidal Energy Power Plant
Team Proposal: Only members listed on the Proposal's Contributors tab will be able to edit this Proposal. Members can request to join the Proposal team on the Contributors tab. The Proposal owner can open this Proposal for anyone to edit using the Admin tab.  
By:  dbayne
Contest: Energy Supply Workspace 2016
How can greenhouse gas emissions from electricity generation be reduced?