# Problems and Questions

• After the storm is over, how can we transport the EMU devices to where the next hurricane is. – One solution would be to tie the EMUs into long chains, which would be towed closer to the next storm by maintenance ships.
• We do not yet have effective equipment for manufacturing third energy, and we also do not have suitable material for its storage. (Universities and the chemical industry may be able to assist in solving this problems).
• No equipment for the collection of the released carbon dioxide is yet in production. This equipment also needs to be efficient enough.
• The functionality of the EMU in a hurricane requires research and testing by the marine industry. It also requires more money than is currently available.
• The final implementation of the idea would require investment in the scale of five times the US public debt!;-)

## Producing electrical energy The wind hitting the device pushes it on the water parallel to the water surface. In this case the airfoils below the water surface tend to rotate the device. The wind hitting the aerofoils obave the water surface also rotates the device, controlled by computers to attain attain the maximum output. The airfoils both below and above the water surface normally rotate the EMU to the same direction. The rotation speed is controlled by adjusting the output of generators through computers and through the eccentric couterweights, which are used to create a suitable moment that resists the rotation caused by the storm.

The aim is to make the device rotate on the water surface so as to maximize the production of energy and to minimize the occurrence of rotation-impeding pressures on airfoils surfaces ‘A’ and ‘B’ (see image) below the water surface.

As the above image shows, the torque created by the generators’ eccentric counterweights is always equal but directionally opposite to the combined torque caused by the pressure of the wind above the water surface and the pressures generated on airfoils surfaces ‘A’ and ‘B’ below the water surface.

In view of energy production, the ideal would appear to be a situation where the pressure on airfoil surface ‘A’ is high than the pressure on surface ‘B’ below the water surface low. Then the rotational speed of the device would not be too high, and the generators would effectively  slow down the rotation, meaning that the power output of the generators would need to be fairly large. In this situation  the efficiency of the energy production would be at its highest and it could be maintained  at a constant level.

This means that by increasing the output of the generators, or the torque of the counterweights, we can direct a pressure on airfoils surfaces (A) below the water surface. The higher this pressure is the slower the device will move forward in relation to the water.

In contrast, to increase the device’s propagation speed, the output of the generators  is decreased, which effectively decreases the pressure on surfaces ‘A’; i.e. the pressure that slows down the propagation. If needed, the motors can be used to increase the pressure on surfaces ‘B’.

In addition, we can deduce that through appropriate adjustments to the output of the generators, we can turn the kinetic and potential energy of the water into electrical energy by directing pressures to surfaces (A) and (B).

## The resistance of the water impedes the movement of the EMU In this section we will take a closer look on the problems relating to the EMU’s movement.

Generally speaking, the EMU’s electricity output depends on both the propagation speed of the EMU’s center of gravity and the EMU’s rotational speed, both of which are generated by the wind.

The propagation of the EMU is impeded by the mass of water in front of it that needs to be moved behind the device. The deeper the EMU is in the water while advancing, the larger is the mass of water that needs to be moved and also the resistance to propagation 🙁

When the device rotates on the water, the airfoil surfaces (A) and (B) (see image) below the water surface are subject to pressures. These pressures depend on the peripheral speed of the EMU’s aerofoils compared to the propagation speed of its center of gravity (with respect to the surface of water). If these two speeds are equal (directionally opposite below the water surface), the aerofoil surfaces (A) and (B) below the water surface will be subject to almost equal pressures, at least in theory.  Additionally, the kinetic friction between the contact surfaces of the device and of water will be at its minimum.

If the propagation speed of the device’s center of gravity is greater than the peripheral speed of the airfoils, then the pressure on surfaces (A) will be greater than the pressure on the surfaces (B). The pressure differential thereby created tends to increase the rotational speed, which at the same time tends to decrease the propagation speed.

If the propagation speed of the EMU’s center of gravity is smaller than the peripheral speed of the airfoils, then the (B) surfaces will be subject to a greater pressure than the (A) surfaces. The pressure differential thereby created tends to decrease the rotational speed, which will increase the propagation speed.

Furthermore, the deeper the EMU is in the water while advancing, the greater will be the total surface area of airfoils below the water surface, which will increase the forces impeding the rotation.

To maintain the resistance caused by water as small as possible, the devices should be designed and built as light-weight as possible and made to rotate on the water surface so as to minimize the occurrence of rotation-impeding pressures on the aerofoils below the water surface.

With appropriate adjustment of the output of generators, which are controlled by pressure sensors, we can requlate the water pressures on airfoil surfaces ‘A’ and ‘B’ below the water surface. The optimal conversion of kinetic and potential energy of waves, as well as the kinetic energy of the wind into electrical energy is based on this.

## Minimizing rolling resistance

Now, let us imagine a situation, where the device is light and the output of the  generators is adjusted so that, when the device starts moving, the peripheral speed of the airfoils and the propagation speed of the device’s center of gravity remain continuously equal with respect to water.

In this case, the pressures on the airfoil surfases ‘A’ and ‘B’ below the water surface would be as equal as possible and the kinetic friction between the contact surfaces of the device and water would be minimal. This would mean that as litle energy as possible is wasted to warm up the seawater in the whirlpools generated by the friction and the airfoils under pressures.

The wind pushes the device that rotates on the water as freely as possible.

This is analogous to the wheel of a car rolling freely on the road pushed by the car and its engine.

Turn the EMU into a game – and save the world:-/