SUNFLOWER

Jose Carlos de Silva and Leonardo de Silva
Designed for Site #1 in Dubai, near Ras al Khor Wildlife Sanctuary.

Design Submission for the 2010 Land Art Generator Initiative Design Competition

Artist’s descriptive text:
SUNFLOWER Concept
Flowers, as plants in general, capture sunlight during the day, they transform the sunlight energy into chemical energy and by consuming carbon dioxide and water, they generate biomass and oxygen. Many flowers also follow the sun in order to maximize their exposure to the light that sustains their life. In an attempt to mimic nature, we present a system that, like plants and flowers, transforms sunlight into another form of energy that is more suitable for our needs. A giant ‘flower’ stretches up to the sky with an intelligent body that adapts during the day in order to directly expose its petals to the solar rays. With its petals, consisting of tens of solar collectors, it transforms light into electrical energy. Part of this energy is given away to the electricity grid, while another part is stored in the form of hydrogen inside balloons that will inflate and, when hydrogen is consumed in order to produce electricity, deflate, giving the SUNFLOWER an ever-changing shape, like it was breathing. The mix of different kinds of ‘petals’ will give every SUNFLOWER a unique shape.

These SUNFLOWERS are placed within a network of paths (branches) that extend through the site, creating a park where visitors can safely come and enjoy the view, and the comfort given by the shadow projected by the SUNFLOWER. There will be no more noise than the air running through the landscape on the site.

How it works
The SUNFLOWER is a solar photovoltaic electric generator. It is composed by a series of solar balloons with a concave reflective surface that captures and concentrates light 400 fold and directing it to a photovoltaic panel. The group of spheres that compose the SUNFLOWER follow the sun by bending the ‘stem’ or supporting structure. The electricity generated is then partially sent to the grid and partially used to generate Hydrogen using fuel cells, devices that can transform hydrogen and oxygen into water and electricity in an efficient, silent and reliable way to be stored and later used to generate electricity at night or during peak hours.

3- How much it generates:
The SUNFLOWERS in SITE 1 can generate up to 1 MW of continuous electricity 24 hours a day. This can be adapted depending on need; it could generate less Hydrogen for the night and send more electricity to the grid during the day.

Harvesting, Storing
The SUNFLOWER generates the electricity during the sun hours. Part of the electricity is sent to the grid and part is used to produce Hydrogen by water electrolysis which is then stored in low pressure hydrogen balloons. When in need of electricity between sun hours, for example at night, hydrogen is combined with the oxygen in the air to produce electricity and water using fuel cells. The water generated by the fuel cell is stored for future hydrogen production in a closed loop to avoid waste. In the process, oxygen is constantly being taken from and released into the atmosphere. Hydrogen can be stored for any period of time without any losses as opposed to expensive and complex batteries.

The SUNFLOWER has two types of petals
1. The solar panel: inflated, balloon-shaped concentrators. Each 8-foot-diameter concentrator is made of plastic film—the same kind of plastic film used to bag potato chips, pretzels, and so on—with a transparent upper hemisphere and a reflective lower hemisphere. When inflated with air, the concentrator naturally forms a shape that focuses or concentrates sunlight onto a PV cell placed at the focal point. This means we need fewer cells to produce a lot more electricity. In fact, a single cell in our concentrator generates about 300 to 400 times the electricity of a cell without a concentrator (text via: Cool Earth Solar).

The inflated structure is naturally strong—strong enough to support a person’s weight—and aerodynamically stable, able to withstand winds of 125 miles per hour. Finally, the transparent upper surface protects the PV cell and mirrored surface from the environment, including rain and snow, as well as insects and dirt.
Each concentrator has additional structural components: a small steel strut and a harness. The steel strut, tethered in place, holds the cell at the focal point inside the concentrator and provides a conduit for a small water loop that cools the cell. A lightweight, flexible steel band forms a harness around the circumference of the concentrator and is used to hold and point the concentrator (text via: Cool Earth Solar).

2. The Hydrogen Balloons: Made of plastic materials in order for them to deflate and inflate as the pressure changes inside them. The pressure is kept low (under 10 bar) in order to make the balloons cheaper to manufacture and to save energy by storing hydrogen at the same pressure it is generated within the electrolysers. The balloons will be deflated in the morning when the Hydrogen stock has been depleted by the electricity consumption during the night and will re-inflate during the day as the sun provides the energy to produce new hydrogen. This inflation and deflation will give the SUNFLOWER an infinite shape change just like flowers that open for the sun in the morning and close at night.

The stem
The SUNFLOWER stem consists of a central flexible structure surrounded by cables that run up and down giving it stability. These cables will then control the SUNFLOWER orientation by pulling and letting go according to need, which will give the SUNFLOWER an infinite range of movement and allow it to follow the sun without the need of any other complex multilink system. The movement will be slow and silent, just like in a sunflower, without affecting the wildlife, site visitors or anything.

The base
The SUNFLOWER base is a concrete underground machine room that works as foundation. In this room we find the SUNFLOWER movement control equipment, the hydrogen generators and fuel cells, the electrical connection to the grid and a water tank for storing the water generated at night that will be used to produce hydrogen during the day. The water tank will empty and fill depending of the amount of hydrogen available in the SUNFLOWER.

Scalability of the design
Since the idea is made of beautiful, independent, fully functional elements (SUNFLOWER s), the scalability is infinite, it can be put all over the grid, on top of buildings in the middle of parks in fuel stations, along the road. It is entirely safe, very light and with no exposed moving parts.

Environmental Footprint

Construction: It requires the transportation of the steel cables and structure (prepared in a factory), the deflated balloons, some water and all to be assembled in place with no heavy equipment.

Life and maintenance: The SUNFLOWER will require minimal maintenance, the whole process is contained either in sealed balloons or in the machine room in the basement with no exposed moving parts, and there is minimal need of cleaning. The solar panels and hydrogen balloons are easily replaced whenever needed. The flexible stem can flex all the way to the floor level to allow maintenance to be done with just some ladders or small equipment to reach the upper parts of the SUNFLOWER. The balloons concentrate the light received into the photovoltaic cell; therefore no reflection of light will be emitted to the atmosphere distracting birds and airplanes.

End of life cycle recycling: All parts are made of entirely recyclable materials, steels and plastics. They could be restored or recycled to create new generators in a cradle-to- cradle fashion.

Safe: In case of a catastrophic event, the hydrogen stored in low pressure balloons will disperse immediately in the atmosphere (zero pollution or explosivity). In the extreme case of a SUNFLOWER falling down the solar balloons are so light that they will create minimal damage absorbing most of the impact and the electric generation will stop the moment the panels stop receiving sunlight.

low-res version PDF of submitted boards