MoTGen (Motionless Thermal Generator)
A novel device to convert thermal energy into electrical energy, with high efficiency and no moving parts. Could be applied to any situation which currently uses a heat engine to create electrical energy, replacing conventional Stirling and steam engines
Team Concept
Our system proposes we use a team of MoTGens to tap energy from the naturally occurring heat flow found underwater at hydrothermal vents. Our chosen vent system is part of the Juan de Fuca Ridge, off the coast of Oregon and Washington. Each MoTGen would be positioned over a hydrothermal vent, and the temperature gradient from the 350+°C hydrothermal fluid on the hot side to the 2°C sea water on the cold side, will create a massive heat flux, of which, a certain percentage (less than 55% as dictated by the Carnot limit) will be converted to electric energy. Our model generator is made to fit a 1 m wide vent with average conditions, such as a 350°C temperature, and 3m/s flow. Such a vent would naturally transfer thermal energy from the hydrothermal fluid to the ocean water at 4.7 GW. We estimate that one MoTGen will be able to transport about 180 MW of that, which, even at a low 25% efficiency, would create 45 MW of electrical power. The whole operation would lower the temperature of the outbound hydrothermal fluid by 13°C. To carry all this electrical power back to where it can be used on land, we must use a massive underwater power line. While challenging and costly, this is not unprecedented- similar projects are planned in Europe, including NorNed, a line to transfer at least 700 MW of electrical power from Norway to the Netherlands at 450 kV. In our setup, one such power line would service a series of generators by following the fault line. In our project proposal, we assume a team of 150 model-sized MoTGens will be used, even though in reality the MoTGens used would probably be smaller, as there is a greater quantity of smaller vents.
The advantage of our system over more common land-based systems is that it provides renewable energy at a large level. Many consumer level products such as residential solar panels are good energy saving devices and could help alleviate some power needs, but overall are comparable in output to a gas powered backup generator, and would not work as large scale energy providers. Much of the energy circulated in the grid is used in the commercial and industrial sectors, not in the residential sector. A large part of the industrial and commercial sectors operates nonstop 24 hours a day, greatly limiting the usability of solar and wind energy, as neither provide constant power output. Our hydrothermal energy system would be able to provide large amounts of base-load power for a very cheap price, as it would require no routine maintenance or materials once installed. In terms of energy production, one MoTGen team would provide the same amount of energy as about 2 or 3 nuclear power plants, but without the radiation hazard.
One of the problems with our system is its location- the hydrothermal vents are about 200 miles away from the coast and 2.2 km underwater, which makes maintenance expeditions extremely expensive. For this reason, the machine has no moving parts whatsoever, and an indescribably rugged design. After installation, the generators will not require any kind of scheduled maintenance.
Our initial, gross estimates (more detailed estimates will be known after Phase A is completed) place the construction and installation of each MoTGen at about $2 million. The power line would cost about $850 million, meaning our model team of 150 MoTGens and a power line would cost $1.15 billion. Due to the virtually nil maintenance costs, after the startup costs, the system would just produce energy. Selling the electricity at 7cents per kWh (US average for industrial use in 2008), the team of MoTGens would produce $345 million per month, enough to pay off startup costs in 3 to 4 months.
Team Description
Two seniors from Cinco Ranch High School who are dedicated to discovering the mathematical mechanisms behind physics and then applying it to the world in a useful way. Combined, they bring knowledge in Chemistry, Thermodynamics, Differential Equations, Tensor Equations, Electrical Engineering, Acoustics, Computer Science, and Physics in general to their team.
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