On the way to Denver, the Solartaxi has established another record by reaching an elevation of 10,603ft, the highest point of the entire journey: Another proof for the capability of the solar powered vehicle that has traveled over 38 000 kilometers so far! This is a reason to talk with Andreas Manthey, Vice-Chairman of the German Association for Solar Mobility about the relevance of Louis Palmer's solar world tour and the future potential of solar mobility.Club of Pioneers: The solar world tour has reached the US and the Solartaxi is still “running like a Swiss Clock”, says Louis Palmer. Is that what you’ve expected when the Solartaxi started a year ago?Andreas Manthey: Yes, because electric vehicles are very reliable. Stationary electric drives usually are in use 8 or 16 hours a day. When you put them into vehicles, its like holidays for them.CoP: What do you think of Louis Palmer as a person? Manthey: I met him, when he started a year ago. When he showed pictures of his earlier trips (e.g. With the bike through Africa, with the ultralight airplane through South America), then you know, that this trip is not a big challenge for him. It is admirable that somebody is so convinced to bring a good message around the world.Louis and the Solartaxi at the beginning of the tour
CoP: What do you think of the Solartaxi vehicle (from the engineering point of view)?Manthey: The cooperation with the “Ingenieurschule Biel” was a good idea. I know some of them, because they won the swiss solarcar races “Tour de Sol” from 1986 to 1992 with their teamleader Prof. Jeanneret. The car is leightweight and has very efficient components. So the solar energy can be used to the maximum. An interesting feature of the car is the possibility to change the position of the steering wheel from LHD to RHD. This switches guests to drivers and this switches a lot more in their heads... CoP: Louis Palmer makes solar mobility popular, but there are still problems to solve: Energy must be stored for cloudy days and the engines don’t offer much driving pleasure. What can be done to make solar mobility more attractive to consumers?Manthey: Electric engines offers much more driving pleasure than combustion engines, because of their high power output. An electric drive can deliver 5 to 10 times its nominal power for acceleration, thats why they are used in trains. The batteries are there, but only as prototypes. For electric bikes and powertools, cheap batteries with high energy and power density are available. They will come for cars also. Solar mobility becomes attractive by itself. Rising prices for fossil fuels and lower prices for renewable energies will meet soon, I would say even in a lifetime of a car. The users need to be informed about the market offer, by internet, by exhibitions (e.g. Ecomove-berlin.de) or by newspapers (e.g. ecomobil-magazin.de).Andreas Manthey, Vice-Chairman of the German Association for Solar Mobility
CoP: Your association wants to pave the way for solar mobility. Unfortunately, car manufacturers exhibit no interest in sun power so far. Why is it so?Manthey: This is not true. E.g. Volkswagen researches the use of biofuels, which is also solar mobility. Years ago Audi presented its hybrid Audi duo in front of a solar charging station. Next year Mitsubishi will sell the first i-MieV-EVs in Germany, Toyota will present a Prius plug-in hybrid which is actually in a fleet test in France, and we are talking about a network of charging stations. The German Solarcar Federation and other NGOs are preparing a network of “renewable” charging stations through Europe (LEMnet).CoP: How will solar energy influence the automotive future in your opinion?Manthey: Solar energy is just used to acclimatise cars. With a solar panel on the roof of the car, a fan is powered, which exchanges the hot air inside the car. Today the surface of a car is not big enough to power the car solely by the solar energy which shines on the car. On every square meter the sun radiates 1000 watts. With a surface of a car of 1.8 by 4.5 meters you can earn 8 kW at the maximum. With the efficiency of todays solar panels of about 15% (prototypes about 25-30%), this results in about 1.2 kW maximum electric power. So in a sunny day you can earn between 6 and 10 kWh on a flat surface. With my electric vehicle Citroen AX électrique which needs about 15 kWh per 100 km, I could drive between 40 and 65 km on a sunny day. This may be enough for a large amount of cars. But when I use solar energy on my car, I would reduce the energy consumption of my car before, by reducing the weight and the air drag coefficient before using solar panels. On the roof of my house a solar array of 20 square meters can produce 1800 kWh per year in Germany, this are about 12.000 km per year with my car on solar energy only. These solar panels are connected to the grid and the solar energy produced may be used by other consumers during the daytime when my car is not there for charging. In the night I take energy from the grid when nobody else wants it. So grid connected solar cars help to reduce the impact to the electric grid. CoP: To what extend solar energy could play a role in aviation or in maritime navigation?Manthey: Solar ships are a very interesting application of solar energy. They are used in summertime when the sun is shining, they are used on sunny days, nobody wants a boat trip on a rainy day. On the water there is no shadow and the electric boat motors are not needing this high power to accelerate as a car does. It needs a continuous current at a low level. Thats why solar boats just exists in many locations.
An other possibility to power boats with renewable energy is a large kite of several thousands of square meters which throws a ship over the ocean. The company SkySails equipped a ship and made a successful test trip across the Atlantic Ocean. Not to forget, that long ago ships crossed the seven seas with wind energy.
In aviation solar energy is used to power an unmanned test plane which flew several times around the world. Some years ago the University of Stuttgart built a “solar zeppelin” of 16 meters long which was radio controlled and equipped with a camera.SkySails
CoP: Do you think there will be a mass production of vehicles powered by solar energy one day?Manthey: We need the mass production of energy efficient electric vehicles with a consumption of under 10 kWh/100 km for a two seater and not more than 15 kWh/100 km for a four seater vehicle which are powered by an electric grid full of renewable energies, as in Norway. Several car manufacturers announced electric vehicles for the next years. I hope that they are energy efficient with low weight and good aerodynamic qualities. A good four to five seater car must not be heavier than 500 kg as Toyota (and others) showed with its 420 kg 1/X at the Geneva Auto Show in 2008. That good aerodynamic qualities are possible for a series car was proven by GM with its EV1 with only 0.195 drag coefficient or Audi A2 with 0.25. In the beginning of the 90s Amory Lovins from Rocky Mountains Institute presented the Hypercar, a low weight low aerodynamic and rolling resistance electric car with a range-extender. GM built a prototype “Ultralite”. Where is it today? Not in our showrooms! If India and China will copy our mobility patterns the number of cars worldwide will raise from some 600 million cars to several billions. And if they are powered by combustion engines this is to much for our planet. If we want to power a car by natural energies, and we have an area of 100 by 100 meter, we may take sunflower seeds and produce pure plant oil, then we can produce about 20.000 km a year. If we use the whole plant with biomass to liquid BtL we get about 60.000 km, with biogas 67.000 km. But if we “plant” solar power and use electric vehicles we will get 3.2 million kilometer from this area per year, even much more with wind energy.CoP: Mr. Manthey, thank you very much for this interview!
Conducted by Jörg FrommannImages: Louis Palmer, Andreas Manthey, SkySails