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Dynamic tidal power

Co-inventor Kees Hulsbergen presenting the principles of DTP at

Tsinghua University in Beijing, in February 2010.

Dynamic tidal power or DTP is an untried but

promising technology for tidal power generation. It

would involve creating a long dam-like structure

perpendicular to the coast, with the option for a

coast-parallel barrier at the far end, forming a large 'T'

shape. This long T-dam would interfere with

coast-parallel tidal wave hydrodynamics, creating water

level differences on opposite sides of the barrier which

drive a series of bi-directional turbines installed in the

dam. Oscillating tidal waves which run along the coasts

of continental shelves, containing powerful hydraulic

currents, are common in e.g. China, Korea, and the

UK.[][1][2][3]

The concept was invented and patented in 1997 by

Dutch coastal engineers Kees Hulsbergen and Rob

Steijn.[4]

Description

Top-down view of a DTP dam. Blue and dark red

colors indicate low and high tides, respectively.

A DTP dam is a long barrier of 30 km or more which is built

perpendicular to the coast, running straight out into the sea,

without enclosing an area. Along many coasts of the world, the

main tidal movement runs parallel to the coastline: the entire mass

of the ocean water accelerates in one direction, and later in the day

back the other way. A DTP dam is long enough to exert an

influence on the horizontal tidal movement, which generates a

water level differential (head) over both sides of the dam. The

head can be converted into power, using a long series of 

conventional low-head turbines installed in the dam.[5]

Maximum head difference

Estimates of the maximum head difference that can be obtained from a variety of dam configurations are based on

numerical and analytical models.[][6]

Field information from measured water level differences across natural barriers

confirms the creation of significant head. The (maximum) head difference is more than what would be expected in

stationary flow situations (such as rivers). The maximum head difference reaches values up to a few m, which can be

attributed to the non-permanent character of the tidal flow (acceleration).

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Benefits

High power output

It is estimated that some of the largest dams could accommodate over 15 GW (15000 MW) of installed capacity.[7]

A

DTP dam with 8 GW installed capacity and a capacity factor of about 30%, could generate about 21 TWh annually.

To put this number in perspective, an average European person consumes about 6800 kWh per year, so one DTPdam could supply energy for about 3.09 million Europeans.

[8]

Stable power

The generation of tidal power is highly predictable due to the deterministic nature of tides, and independent of 

weather conditions or climate change. Power output varies with the tidal phase (ebb, flood), but this can be avoided

by combining two dams, placed at certain distance from each other (in the order of 150-250 km), each generating

maximum electricity output when the other is generating minimal output. This provides a predictable and fairly

stable base load to the energy grid, unlike wind or solar power.

High availability

Dynamic tidal power doesn't require a very high natural tidal range, but instead an open coast where the tidal

propagation is alongshore. Such tidal conditions can be found in many places around the world, which means that

the theoretical potential of DTP is very high. Along the Chinese coast for example, the total amount of available

power is estimated at 80 - 150 GW.

Potential for combined functions

The long dam can be combined with various other functions, such as coastal protection, deep sea  – and LNG ports,

aquaculture facilities, controlled land reclamation and connections between islands and the mainland. These

additional functions can share the investment costs, thus helping to lower the price per kWh.

Challenges

A major challenge is that the proof of DTP functioning can only be demonstrated by putting it in practice. Testing

the concept of DTP at a small scale within a demonstration project, would not be effective, since almost no power

would be yielded. Not even at a dam length of 1 km or so, because the DTP principle is such that the power

generation capacity increases as the square of the dam length increases (both head and volume increase in a more or

less linear manner for increased dam length, resulting in a quadratic increase in power generation). Economic

viability is estimated to be reached for dam lengths of about 30 km.

Demonstration Project

A demonstration project under consideration in China would not involve construction of a dam, but instead feature a

newly cut channel through a long peninsula with a narrow isthmus (neck). The channel would feature a head of 

about 1 - 2 meters, and be fitted with low-head bi-directional turbines, similar to the type which would be used for

full-scale DTP.

Status of technological development

No DTP dam has ever been built, although all of the technologies required to build a DTP dam are available. Various

mathematical and physical models have been conducted to model and predict the 'head' or water level differentialover a dynamic tidal power dam. The interaction between tides and long dams has been observed and recorded in

large engineering projects, such as the Delta Works and the Afsluitdijk in the Netherlands. The interaction of tidal

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currents with natural peninsulas is also well-known, and such data is used to calibrate numerical models of tides.

Formulas for the calculation of added mass were applied to develop an analytical model of DTP. Observed water

level differentials closely match current analytical and numerical models.[]

Water level differential generated over a

DTP dam can now be predicted with a useful degree of accuracy.

Some of the key elements required include:

•• Bi-directional turbines (capable of generating power in both directions) for low head, high-volume environments.Operational units exist for seawater applications, reaching an efficiency of over 75%.

•• Dam construction methods. This could be achieved by modular floating caissons (concrete building blocks).

These caissons would be manufactured on shore and subsequently floated to the dam location.

•• Suitable sites to demonstrate DTP. A pilot project of DTP could be integrated with a planned coastal development

project, such as a sea bridge, island connection, deep sea port, land reclamation, offshore wind farm, etc., built in

a suitable environment for DTP.

Recent progress

In December 2011 the Dutch Ministry of Economy, Agriculture and Innovation (EL&I) awarded a grant funding

subsidy to the POWER consortium, led by Strukton and managed by Arcadis. The maximum grant is about 930.000

euro, which is matched by a similar amount of co-financing from the consortium partners. The POWER group

conducts a detailed feasibility study on the development of Dynamic Tidal Power (DTP) in China in a 3-year

programme jointly conducted with Chinese universities and institutes.[9]

The commitments of the programme to

achieve by 2015, registered under the UN Sustainable Energy for All initiative include:[10]

•• Determine most suitable sites for DTP implementation in China, Korea, and the UK

•• Complete detailed feasibility studies for two DTP pilot power plants in China

•• Complete pre-feasibility study for one full-scale DTP power plant in China

•• Worldwide dissemination of technical information regarding DTP among relevant target groups

In August 2012, China's National Energy Administration formed a consortium of companies and research institutes,

led by the Hydropower and Water Resources Planning and Design General Institute, to investigate DTP. A bilateral

agreement on DTP cooperation was signed between China and the Netherlands on September 27, 2012.[11]

References

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Article Sources and Contributors 4

Article Sources and ContributorsDynamic tidal power  Source: http://en.wikipedia.org/w/index.php?oldid=563669733 Contributors: Crowsnest, Ernestfax, Hangshi11, JNW, Rehman, UNguyinChina, 15 anonymous edits

Image Sources, Licenses and ContributorsFile:Hulsbergen presents DTP at tsinghua.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Hulsbergen_presents_DTP_at_tsinghua.jpg License: Creative Commons

Attribution-Sharealike 3.0 Contributors: UNguyinChina

File:DTP_T_dam_top-down_view.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:DTP_T_dam_top-down_view.jpg  License: Public Domain Contributors: UNguyinChina

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