Renewable energy

RENEWABLE ENERGY

Energy generation has become an urgent, strategic issue at the global scale. At present, about 80% of world electric energy is produced from thermal plants making use of fossil sources (oil, gas, coal). The economical, geopolitical and environmental problems related to such sources are becoming every day more and more evident. Nuclear plants have their own problems related to security aspects and radioactive waste management. For these reasons it is of primary importance for the scientific community to explore and support new renewable energy technologies, able to provide more efficient solutions than the existing ones to the severe energy shortage of the planet.

WIND POWER

Today's technology is just capable of scratching the surface, in few favourable points, of the enormous energy field contained into the wind. Wind turbines cannot reach higher and touch altitude wind, they are already close to their dimensional limits: difficultly hubs can be positioned at more than 100 m above the ground, the holding structure grows exponentially heavier, more unstable and above all more expensive with the height.

KITE GEN

To reach altitude wind and exploiting its higher kinetic energy, the Kite Gen project starts from a radical change of perspective: no longer heavy and static plants like current wind turbines, but instead light, dynamic and intelligent ones. In the air, to subtract energy from the wind at an altitude of 800 / 1 000 m, power kites, semi-rigid automatically piloted high efficiency air foils. The power kites are anchored to a revolving structure on a vertical axis at ground level, which conveys the energy thus generated.

A clear advantage of this technology is visually suggested in the illustration below. The essence of the Kite Gen concept is comparable with a wind turbine, whose most efficient part are the wing tips - in red - where the highest speeds are reached; but only the truly needed components remain, high speed wings and the generator, the latter conveniently moved to the ground. The resulting structure, base foundation included, is much lighter and cheaper. Moreover the operative height can be adjusted according to wind conditions.

POWER STATION

The KSU (Kite Steering Unit) is the unit that allows to automatically pilot a power kite or an array of power kites over a predefined flight path. The power kite is manouvered by differentially unrolling and recovering the two lines on two winches controlled by engines.

Each Kite Gen power plant is composed by several KSUs pulled by the power kites along a ring-shape circular path at ground level. At the very core of the project stays the software that, receiving data also from on-board avionic sensors, autonomously pilots the power kites, so that their flight patterns can be controlled, synchronized and normally directed to maximise the production of energy.

With such configuration, a single Kite Gen power plant is able to intercept very large amounts of altitude wind. In the illustration below is shown the area swept by a plant with a circular path of 800 m diameter: the same quantity can be reached by approx. 150 latest generation wind turbines. It has to be noted that wind turbines need to be spaced to avoid shading one another and decreasing the total yield, so these would require a territory of more than 40 Km². The Kite Gen power plant, a safe area around included, uses approx. 5 Km².

Energy production takes place in a distributed manner at each unit, thus avoiding unmanageable sizes of the electrical equipment.

The modular approach makes possible to build very powerful Kite Gen plants, where as the diameter at ground level of the circular path grows, the area swept increases to the square and therefore the total wind power. 100 MW Kite Gen power plants, not much larger than the illustrated example, diameter at ground level of the circular path of approx. 1 000 m, are estimated to deliver a cost of energy produced lower than 0.03 Euro per kWh. This value is bound to be further enhanced, since 1 000 MW (1 GW) plants are under study.

ENVIRONMENTAL CONCERN

Wind power generation methods can be all labelled as 'clean' technology, with zero emissions of CO2, of other green house gases, of ashes and particulate matter. The positive effect on the environment, coming from the -quickest and most efficient possible- substitution of the current polluting technologies based on non renewable sources, is the main drive behind Kite Gen Research.

It must be added that Kite Gen technology, when compared to wind turbines, much as it foresees a lower cost of energy produced, in the same way returns improved results in terms of energy balance, that is the calculation of how long a power plant must operate to produce the amount of energy that will use in its entire life cycle (from raw material extraction to final disposal).

The environmental impact should be then analyzed not only on a global scale, but also related to the localization of each power plant, where the following main factors arise:

Scenic and visual impression

The aerial part, since the power kites fly at an altitude of 800 / 1 000 m tethered by small diameter lines, is much less visible than today's wind turbines.
The ground systems are concentrated along a circular path, while the vast majority of the occupied area is available for agricultural activities. The visual impact can be enhanced by specific architectural design; it must be noted anyway that, equal the installed power, land use is lower than what required by current wind technologies, with the possibility to concentrate the needs into few large installations.

Shadows

Power kites project little or no shadow, the Sun tends to completely dissolve the shadow of any object if positioned at a distance from the ground larger than approx. 100 times its width.

Birds

Several studies suggest that overall bird deaths due to wind turbines are much less than those related to other anthropic causes (power lines, pesticides, cars, buildings with windows, etc.).
Specific and detailed analysis will have to be conducted for the Kite Gen power plants, but the higher operative height of the power kites appears to be a positive factor, considering also that the speed of the lines' movement decreases as they get closer to the steering units at ground level.

Noise

While the noise produced by the aerial part is negligible, the ground systems can be compared to a low speed railway with good soundproofing (50 dB at 200 m distance).