tirsdag 11. juni 2013

Believe in the unbelievable!


by Ida Fuchs, Higher Executive Officer, SFFE - Centre For Renewable Energy, NTNU

Happy renewable times

We live in the happy situation to observe an enormous growth of renewable energies. Some of you might say that it is still not enough, while others think it is too much, but really, personally, I am proud of every brain who contributed with a part to the big puzzle. When I read the news and found that in Germany, my home country, sun and wind covered half of the power capacity demand in April 2013, I felt simply happy and really proud of my fellow engineers, scientists, economists and also politicians. The latter provided really great programmes to give renewable technologies the necessary push into the business. A great example is the 100.000 Roofs Programme, a subvention programme for photovoltaic installations.

World’s Firsts
A lot of exciting things happen in the renewable energy field and you can find many “World’s Firsts”. I was the lucky master student who got the possibility to write a master thesis about the world’s first autonomous wind and hydrogen system and it is located here in Norway on the small island Utsira. And not far away from there the world’s first floating wind turbine was set into the sea. Lately, I came across the incredible promising Sahara Forest Project where they grow food in the desert by using a smart process to condence fresh water out of the sea. And another incredible project is the Omega System where the growth of algae cleans wastewater, captures carbon dioxide and ultimately produces biofuel without competing with agriculture for water, fertilizer or land. 


The unbelievable
Something that all those projects have in common is at least one person with an undying engine of idealism. They must have met a lot of criticism and doubt on their path. They must have fought against many strong opponents. And I am sure, very often they could not answer the difficult questions with a reasonable answer, but only with their hearts: “This is true, because I believe it to become true!” They believe in the unbelievable.

Albert Einstein said: "We can't solve problems by using the same kind of thinking we used when we created them." We must think different. We must expand our sight and give the unbelievable thought a chance to evolve. That is what the architect Michael Pawlyn did, when he let a simple desert beetle be his inspiration for the Sahara Forest Project. The answer is often not there where we try to find it. And nature itself is not seldom the inspiration for various good solutions.

Insects are optimizing transmission power systems
Could you imagine that the solution to some difficult optimisation problems can be find in the behaviour of insects? A large power transmission system is a difficult optimisation problem. The integration of renewable energies into the transmission grid is still a great challenge, especially when considering large systems as the entire European power system.

Imagine Winter Is Coming and you have to buy yourself a set of winter clothes. The optimization problem is to minimize the costs for the clothes while guaranteeing that you do not freeze to death and maximizing your comfort. What you buy will be dependent on what clothes you have from before. You will have to make decisions, if it should be a trousers and a jacket or an overall, if you need wool clothes under or not, if you need a third layer and so on. How thick your jacket should be, will be dependent on the choice of your underwear. It is a combinatorial problem where it is not defined of how many pieces the optimal solution consists, but each solution component is dependent on the other solution components.

That is exactly what power system planners are doing. The pieces of clothes are transmission lines to build or extend. The aim is also to minimize the costs, but this time while guaranteeing the security and reliability and maximizing the integration of renewable energies and the marked performance of the power system. In scientific terms the transmission expansion problem is a combinatorial, mixed integer, non-linear, non-convex, multi-stage problem which is extremely difficult if not impossible to solve with classical mathematical models. And can you imagine that small little ants, of all things, are the ones who can solve that problem?

Ant colony optimization 
An ant seldom comes alone. There is always a second one. And a third. And more. They come in colonies. Have you ever left sugar on the floor and experienced that only one ant came? No, there would be a whole army of ants marching one path directly to the food source. And how is it that they are so efficient?



Ants communicate be a serum they leave on the path they walk, so that other ants can follow. If many ants walk out to search for food, the ant that walked the shortest path would come back to the nest at first, leaving a serum path behind. Other ants would follow that path at first, which would lead to a higher concentration of the serum on that specific path. The path with the highest concentration of serum will be chosen by even more ants. In that way, ants easily find the shortest paths between food sources and nest. This behaviour of the ant colony has been the inspiration for Marco Dorigo to develop a heuristic optimization model, which is capable to deal with exactly that optimization problem we have for transmission expansion (I. Fuchs, 2011).  

The beginning
And this is just the beginning. Ant colony optimization is only one of many swarm optimization techniques that have found their way into technical optimization models. And it is only one example where nature was the smart inspiration. Does that all surprise you? Is not copying nature the most natural thing to do when thinking sustainability? You can’t believe it? - That is why you fail!

Publications
Fuchs, Ida; Völler, Steve; Gjengedal, Terje.
Ant Colony based Transmission Expansion developed for the Nordic Area and Great Britain.
I: PowerTech 2011 Proceedings. IEEE conference proceedings 2011 ISBN 978-1-4244-8417-1. p. - ENERGISINT NTNU

Fuchs, Ida; Gjengedal, Terje.
Ant colony optimization and analysis of time step resolution in transmission expansion computations for wind power integration.
International Conference on Intelligent System Application to Power Systems; 2011-09-25 - 2011-09-28 HIN NTNU

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