Land Art Generator Initiative 2014 Design Competition Winner: Copenhagen’s Solar Hour Glass

Geschreven op 10-10-2014 - Erik van Erne. Geplaatst in Design

As if you were walking along one of Refshaleøen flea markets, you suddenly come across a particular item, an object that you can clearly recognize and at some point relate to.

You probably haven’t seen one of those in a very long time so you feel particularly intrigued by it, somehow captivated.

You start to approach it and its scale starts to look a bit unusual… somewhat extraordinary. Suddenly you realize… this one, is different.

You start walking towards it eager to take a closer look at what appears to be an item taken from no other place than wonderland. You approach the object and now you are absolutely sure… It’s an hourglass. However there’s something particularly different about this one, something that makes you wonder if it really is what it appears to be. It was the very first thing that caught your eye. The majestic hourglass does not appear to be trickling sand or powdered eggshell, instead, whatever material it is, sure is shining as the first sunrays in the morning. There’s a subtle mist around the neck of the hourglass that allows you to clearly see the light “trickling” from one bulb to the other. Is it measuring time? Or is it something else?

You approach the bulb even more and you start to realize you’re not the first one there. Others have beaten you to this numinous spectacle of light. All over the bottom bulb, dozens of people enjoy a summer noon sheltered by the cozy shadow of the top bulb. Some are having lunch, others chatting, a few others reading. Some of them, lying on the subtle slope of the bulb, are enjoying the incredible views of Copenhagen’s harbor and Yderhavnen. Nevertheless, on the east side of the slope, something different appears to be going on. This side, facing the island of Refshaleøen is now being used as stands by people watching an improvised performance by a couple of musicians. It appears as if the hourglass was being host of all sorts of activities.

But you’re still intrigued by that beam of light that appears to be enchanting your eyes. You go on and step on the bulb. There’s a stair that goes along with it right next to you but you feel lively and choose to conquer the slope on your own. You reach the light beam and start to feel some heat. Indeed it is a solar beam, an energy beam that is being reflected by hundreds of small heliostats on top of the upper bulb onto a focal cone shaped mirror that shoots it down the hourglass’s neck.

The effect is just breathtaking. It is a solar hourglass. It’s not measuring time, but instead, producing energy by capturing solar heat and concentrating it on a receiver. You’re amazed. This astonishing object turned out to be somewhat of a power plant. An environmentally friendly and sustainable power producing hourglass that resembles not only the shape of these beautiful artifacts but also the way they work, only using a solar beam instead of sand as a trickling material. You overhear someone saying that at night, the beam goes off and the thin layer of OLED (organic light-emitting diode) that covers the installation, lights up on the surface of both bulbs, transforming the hourglass into a pair of elegantly curved planes that shine off the edge of Refshaleøen. You just have to stay around to see that.

What came to be known as the Copenhagen’s hourglass ended up becoming a beacon in the Refshaleøen’s island. A universal icon facing the harbor as it produces sustainable energy in a visible way thus making visitors and tourists aware of this process.

The Hourglass somehow remind us that energy is just as precious and fleeting as time, and thus we should take care of it, appreciate it… not waste it. The project aims to send an optimistic message to those who visit it; that we still have time to make things right environmentally; that we are not beyond the point of no return… and most importantly, that we don’t need to be.

The Hourglass represents one more step in our search for sustainable, feasible, and beautiful ways of producing clean, renewable and environmentally friendly energy. Along with the earth, the hourglass will keep turning, giving us with every turn, another beam of hope for a brighter and more sustainable future.

Solar Hour Glass 2 Copenhagen The project works as a solar central receiver which consists of an arrangement of small flat mirrors that concentrate their reflection of solar energy on a tank holding a heating medium. The mirrors, also known as “heliostats”, manufactured by Abengoa Solar, a world leader in thermo-electric
solar power stations, are arranged parabolically on top of the upper bulb of the hourglass and reflect the solar heat onto a cone shaped set of smaller mirrors that concentrate these reflections and shoots them down the neck of the installation.

The concentrated beam of solar heat then reaches a receiver, or, heat collection element, which is coated with a special absorber surface that maximizes the transfer of heat from the sun to the heat transfer fluid contained inside the receiver. This heat transfer fluid (HTF), which consists of molten nitrate salt, is heated to temperatures over 600 °C. The HTC is later transferred to a heat exchanger where water is turned into steam that runs a turbine generator. A small percentage of the steam produced is released back to the neck of the hourglass, thus making the solar beam visible to the public.

The higher heat capacity of the molten salt, allows for the system to store the heat energy which allows the installation to continue to produce energy during cloudy weather or even at night. The thermal storage included in the bottom bulb allows for the system to continue producing energy for hours after the sun is gone.

All the energy production and transformation components are hidden inside the bottom bulb thus becoming inaccessible for the general public, making it a safe installation, and taking advantage of the concepts morphology to allocate this elements. As a concentrated solar power technology that employs molten salt as a HTF, the Hourglass should account for a 32% capacity factor, and with a diameter of 50m, the 1960sqm parabolic set of heliostats would concentrate enough heat to produce 6.2MW, which would be enough electricity to power 860 homes, or the greater part of Refshaleøen.

The structure is built majorly out of recycled steel and aluminum extrusion, guaranteeing excellent performance over long periods of time and thus creating no run-offs , by products or emissions of any kind.

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Anders Bekeken