Computer Modeling of Spring Based Gravitational
Tidal Energy Extraction
Andrew Bingham1 and Ken Visser2
Mechanical and Aeronautical Engineering
Tidal energy represents one of the most dependable and predictable sources of renewable energy
available on Earth; without the variations present in wind or the effects of weather on sun, it represents a
guaranteed source of energy once every 12.5 hours. Each day, billions of kilograms of water are lifted
above their normal level under the influence of the moon’s gravity, increasing the potential energy of the
tidal water column beyond that of seawater at low tide. Traditional methods seek to extract this energy by
building a barricade (essentially, a dam) at the mouth of an estuary, trapping the tidal flow and utilizing
standard low-head hydroelectric equipment to generate electricity. However, drawbacks including
construction costs, environmental impact on sensitive ecosystems, and lack of a significant number of
areas in which the technology can be deployed.
The objective of our research this summer is to determine the feasibility of extracting energy
from the gravitational force on the tidal water column through the creation of a computer model of a
theoretical device. One effect that the presence of the tidal water column has is an increase in the
downward force which is exerted below it as it is acted upon by Earth’s gravity. This increased force
represents a potential source of energy, especially in areas such as the Bay of Fundy with a large tidal
range.
The first step required before any computer programming can occur is the definition of the
theoretical device to be modeled. In order to allow for completion of the model within the time available,
a relatively simple device was chosen, consisting of a cylinder containing a spring which exerts a force on
a plate enclosing the top end of the cylinder, as well as a generator to convert the energy which is stored
in the spring into electrical energy. Incoming tidal flow compresses the plate, which is released during
low tide to produce electrical energy through the generator. An early prototype of such as device was
completed and tested previously by an Integrated Design class at Clarkson.
1
Class of 2007, Mechanical/Aeronautical Engineering, Pre-Freshmen Research for Honors Program, Oral
Presentation
2
Assistant Professor, Department of Mechanical and Aeronautical Engineering
In order to determine the amount of electrical energy that can potentially be generated without
actually building a physical device, we must construct an accurate computer model of the spring based
energy extraction device. This model will be created using the MatLab mathematical computing
program, which allows for a range of matrix-based calculations, as well as the development of a
functional graphical user interface for user programs. By developing a program based on standard
physics equations for mass, force, and spring compression, we can accurately model the energy output of
a spring based gravitational tidal energy extraction device. The user interface will be designed to allow
for the modeling of various device configurations and tidal conditions, as well as the graphing of data to
allow for visual interpretation.
Upon completion of the computer model, we will utilize the program to determine energy output
in a range of situations, allowing for an overall view of the feasibility of the spring-based gravitational
tidal energy extraction device. In order to overcome the limitations of the traditional tidal energy
extraction methods, it must be capable of generating significant amounts of electrical energy in situations
ranging from relatively low tidal water column height to extremely high tidal water column height. If
feasible, it would prove an excellent, self-contained option for renewable power, especially in rural areas
where large generating stations in any form are not economically feasible.
References
Cook, Josh, et al, “Tidal Energy Extraction: Milestone 6 & Results and Conclusions.”
Falcao, Antonio, and M. Teresa Pontes. "Ocean Energies: Resources and Utilization." Proceedings of the
18th Congress, World Energy Council (2001).