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Technology

World Solar Challenge Beginning 102

Posted by michael from the spin-long-light-from-the-glory-of-the-sun dept.
Stuart Bowden writes: "Today (Sunday at 8:00am Central Australian time) is the start of the 2001 World solar Challenge, a sort of alternative Cannonball Run in which the solar cars cost up to $10 million. Over the next five days or so thirty three solar powered cars will race 3000km across the Australia desert powered only by sunlight. The official site is at WSC and there is extra gossip, pictures and information at our site at the University of NSW. We'll be doing the web upgrades on the road by begging connections at roadside diners and the occasional satellite phone. The big problem is keeping up with solar cars that don't stop for fuel." Our previous story had more links.
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World Solar Challenge Beginning More

World Solar Challenge Beginning

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  • World Solar Challenge Beginning???? (Score:2, Funny)

    by Anonymous Coward
    World Solar Challenge Beginning
    [ Technology ]Posted by michael on 19:10 Saturday 17 November 2001

    But it's night time!!!
  • How does a gasoline powered car do against these solar powered cars in a 3000km race? In my opinion, this is more like a marathon than a race.

  • Disappointing. (Score:3, Informative)

    by VA Software ( 533136 ) on Saturday November 17, 2001 @11:26PM (#2580169) Homepage
    The World Solar Challenge is a race to motivate research and development into harnessing solar energy

    I haven't looked at all the teams [wsc.org.au] yet, but so far they seem to be aiming to improve performance by improving aerodynamics and reducing weight, not by improving the efficiency of the electricity generation.

    One exception is the aurora [aurorasolarcar.com] team, but I can't find any technical details of the improvements they're claiming.

    • Making Solar Cells a misallocation of resources. (Score:4, Interesting)

      by agotterba ( 312493 ) on Sunday November 18, 2001 @12:05AM (#2580228)
      I've learned a lot about solar cells with the team at my school, including why development of new cells can be a poor investment of resources.

      Solar cells have a theoretical maximum efficency of not more than 50%. Currently, triple junction GaAs cells will get you about 35% (pretty close to the limit). Such an array for a solar car (5m by 1.8 m) can cost in the neighborhood of 500,000 USD. Meanwhile, a 19% Si array can be had for 70,000, and a 13 - 14% array for 10,000. As you can see, the price of an array has something of an exponential relationship to the efficency. To inprove the maximum efficency, you have to have the money to play with some very expensive toys. Only a few companies can afford such equipment (such as Honda and Aurora) and no school that I know of has a suffcient budget. We can (and do) play with making cells, but to commit to designing them and trying various chemistries and encapsulations requires more money than we have. Our object is to make cells that at a given efficency are cheaper than the ones on the market.

      Meanwhile, the only things that slow you down are rolling resistance and aerodynamic drag. Cutting weight usually requires nothing more than a lot of thought into material selection and structural design (not hundreds of thousands of dollars).

      Aero is a little more interesting, as there are tradeoffs betweeen the effective efficency of your array and your aerdynamic drag (for example, a taller car can catch more sun in the mornings and evenings, but will have more drag). These tradeoffs are related to how fast you want to go, and the conditions of the specific race you are designing for (whether it is primarily from north to south or east to west effects how you handle these tradeoffs; a car sloped to a particular side doesn't help if that side never faces the sun).

      Also worth mentioning is that all the American college teams that I know are in the WSC just came off competing in the American Solar Challenge. Teams that did not have large budgets in that race competed in stock class, where they were only allowed to spend $10 per watt that they expected out of their array (limiting them to silicon cells) and lead acid batteries. I do not know if any of those teams went to WSC, but that would explain their use of lower power cells.

      Photovoltaic cell research is one of the mose exciting fields of renewable energy, but when it comes to racing cars, you're more likly to win by buying the best array you can afford, and improving the other aspects of your car.

    • Just a tad expensive (Score:2, Interesting)

      by xenocide2 ( 231786 )
      My roommate is President of the Solar Car team at Kansas State University [ksu.edu]. His team recently finished 5th overall at the 2k1 American Solar Challenge. Since he's president I get to hear all about these things. Very few actual solar panel manufacturers enter, but rather sponsor universities. Sponsorship is why the University of Michigan, near the auto industry capital of the USA, is taking their car, and why we cant afford to ship ours over there.

      As far as the actual electricity generation goes, I'd think its a bit beyond the capabilities of a group of freshman and sophmore (my roommate is a sophmore) undergrads to not only design a better grade solar array, but then manufacture it. Even if some kid did manage it, they couldn't afford the costs. I believe the cost of the current solar array is some 25k, which generates about 14 hp. That gets them up to about 75 mph max, but that eats of the batteries pretty fast.

      Most solar cars don't use the latest and most efficient solar array. If I recall correctly, the latest car from KSU, CATalyst, uses 14 percent efficienct solar panels. The most efficient are gallium-cyanide (or something like that) that are extremely expensive (like 500k or so). Of course there are a few things that can be done besides simply upgrading the solar array. I've heard of shaping the solar cells in inverted pyramids at the near molecular level will increase absorbtion, but the return is expected to be on the order of .1~1 percent. In contrast, redesigning the body of the car gave us about 35 percent less drag. In addition, the concept of "regenerative braking," using the kinetic energy of the car to run the engine in reverse and charge the batteries, greatly increases overall effiency. Essentially, research into solar panel mechanisms requires extensive knowledge in both electrical engineering and mechanical engineering, which few people have, and of those who DO have that exp, few of them would put up with a university salary.

      Yea, I can't spell efficiency, but who cares, I'm only a Computer Science major.
      • Yes, I wasn't really expecting huge technological leaps from the teams that weren't solar cell manufactures ... it just that for an event whose aim is to promote solar power, I did expect some discussion of the advances since last time somewhere. Your pyramid thing, for example; if it works, doesn't increase cost and doesn't decrease yield - if this year's car got 15% instead of 14% that might make a difference.
        • The thing is, my understanding of it is that it does increase cost, because its a chemical treatment. And you could also think of it in oppertunity costs. Solar car has like 10 team members in all, not very many. With so few people you have to work on the more effective parts first.
      • I guess I could verify some of this and add to it since I am the electrical team leader for Kansas State Univ.

        As far as the solar array price of $25K goes....well that's close but I think we did better on price than that. We probably had the best price to perfomance ratio on American Solar Challenge this summer (as far as the array goes). You might be wondering how we keep the cost so low, but still produce an array that makes a lot of power. We encapsulate our own cells. As far as the 14hp number that is equivalent to 10444 WATTS! Sorry to dissapoint all you people out there, but it is not that high. Our array makes somewhere between 100 Watts and 2500 Watts, but that's all I can say. :)

        No one really ever tells you the exact number the solar array makes anyway because it depends on the day, time, and whether or not you are on a rival team.

        On a personal note: Michigan and Rolla kick some Aussie butt!

        -Jeff
    • On this page, [aurorasolarcar.com] they indicate that they purchased 20-22% efficient "space-grade" GaAs cells from an existing supplier, so it sounds like they aren't doing their own geenration improvements, simply purchasing existing known improvements. (Fine by me, just explaining how I read this.)

      --j

    • Re:Disappointing. (Score:2, Interesting)

      by KingPrad ( 518495 )
      The electrical systems of the car are commercial products and any possible tweaking would provide little or no benefit in performance.

      Race speeds of the top cars are above 50 MPH. At speeds up to 45 MPH air drag increases on a linear scale. Above 45 MPH air drag increases geometrically and quickly becomes the main factor in car performance. Teams rebuild their car body if they find a way to shave a few tenths off the drag coefficient.

      The new body on University of Missouri - Rolla's Solar Miner III (rebuilt after the sunRayce last summer) has a drag coefficient of about .09 compared to the previous body's stat of .12. As such, we should get an average speed of several miles per hour faster.

      Other major factors are vehicle weight (obviously), battery type, and solar array type. Lithium ion batteries have much higher retention than older lead-acid batteries that some teams still use and are lighter as well.

      The solar array varies from car to car depending on team budget. Teams with huge budgets have higher efficiency arrays and much more available power. More power does not translate into better performance, though, because over the long haul a more efficient body design with less parasitic power loss will perform much better even with less power.

      KingPrad

    • Re:Disappointing. (Score:1, Interesting)

      by Anonymous Coward
      The team of my university (Delft, Netherlands) does use the triple junction solar cels. That should be the best there is, its still untested in space! Thanx to the European Space Agency and a very generous sponsor [~1M$] they finally could afford this. They even have a few square centimeters of cells that actually flew on Hubble! In addition to this they use Maximum Power Trackers that always load the cells and the battery at the optimum settings.

      It seams to pay off: they currently lead the race!

      Check it out at here [alpha-centauri.nl] [www.alpha-centauri.nl]
    • I work at a chemistry department at the subject of photo-active molecule. Hence I have some background in converting solar energy to electricity. It is very difficult to get a higher effiency for the power-conversion (think max is like 30% at this moment) at a reasonable price. The currently used solar-cells are already mighty expensive

      So in increasing overall effiency should be focussed on lighter and more aerodynamic materials rather than on higher photo-conversion yield systems.

      There are some promessing molecule which can do a better job in light harvesting but these are still in experimental stages.
      The main focuss point in these systems is to transfer to energy for the cell to the 'motor'.
      for more info check to website of the chemistry department at the university lausanne-swiss.
  • I live on the route, and if my calculations are correct they'de be caning (if 50-100km/h is considered caning) past me a couple of hundred meters away. It's such a bastard thing to be lazy. Maybe I take the coolness of it all for granted.

    But alas, i've seen it all before, and in two years time, i'll see it all again...
  • Why is everyone so interested in Solar power? Solar power is not gonna be the alternative fuel of the future, it just doesn't make enough power for pratical use. Fuel Cells and Hydrogen is the way to go. Go here for more info on fuel cells [sciam.com]
    • Competitions of the same type in fuel cells would be difficult to do because (a) fuel cells require tons of research and (b) they're prohivitively expensive. Also, people can basically design their own solar arrays for this type of race, which makes it pretty fun, and it would be hard to find an analogue for fuel cells. So it's not that everyone is interested just in Solar - in fact, lots of people are working on fuel cells as well. Right now, neither solar cells or fuel cells are really usable for full-scale practical use, but wait a few years and some organization will likely humor you with a fuel cell race.

      Of course, by that time you'll likely have read an article on portable nuclear power on Sciam earlier that day and wonder why everybody is so interested in fuel cells, when nuclear is clearly the way to go...

    • Because after the initial investment the power is free and the equipment will work for 20 years. In countries like Morocco with 300 days of sun per year solar power makes a lot of sense. It doesn't have to do a lot, either: run a few light bulbs, a tv, an appliance or two.

      Solar power isn't going to drive your car, but it will certainly power basic home services in many parts of the world.

      KingPrad

    • and you will never have to refill it.

      Modern solar cars used in such races can cruise at 90+ mph, max 130+ mph. Whoa. It's waaay more than enough for me! Give me sufficient night range (supercapacitors or whatever... 80-100 km on batteries will be enough... <rant>yep, 640k RAM IS enough if you do not use GUI crap</rant>) and such car will become my favorite transport.

      The main trouble is NOT the price of manufacturing such car. Mass production will bring the price down. But even if someone invents perpetuum mobile and bulds a car running for free, western public will never buy it unless it has air conditioning, xenon headlights, cup holders, dvd player and all these tech gizmos for $20k -- and solar car can't have ANY of these because its power and weight is very, very limited.

      • A few problems with using solar cars for regular transport: 1. Solar Cars are expen$ive. You would have to shell out a couple hundred thousand dollars for a solar car. 2. They are not safe. Solar cars need to be so light that they would be way to weak to survive a crash. 3. They would be uncomfortable to drive. Most solar cars adopt a low profile for better aerodynamics. This makes it so the driver has to lie down. Also, it would only be a 1 seater. Solar cars are fun toys for universities, but they cannot provide regular transport. You could not design a solar car that would meet current safety restrictions.To meet current restrictions, it would have to have things like metal crumple zones. The solar panels needed to power something that heavy would be too large. With all of this, the clear answer for future automobiles is either hybrid gas/electric, or hydrogen fuel cells powered by hydrogen from clean nuclear power plants.
        • A few problems with using solar cars for regular transport: 1. Solar Cars are expen$ive. You would have to shell out a couple hundred thousand dollars for a solar car.

          Mass production will bring costs down.

          3. They would be uncomfortable to drive. Most solar cars adopt a low profile for better aerodynamics. This makes it so the driver has to lie down.

          Who knows? May be it's best position for the driver? Also when you lie down you can't get a whip spine trauma, can't fly through windshield, etc. It's a erognomics designer's task to make such posture comfortable.

          Also, it would only be a 1 seater.

          Why? If this thing can go 130 mph with one seat, it could go 100 mph with two seats, one behind another. Second seat will _not_ increase drag coefficient, only weight and vehicle length. Solar challenge rules limit solar cell area to the certain number, but you don't have to limit it when you build commuter vehicle. Second passenger compartment will increase vehicle power enough to compensate passenger's weight.

          To meet current restrictions, it would have to have things like metal crumple zones

          No. With weight about 200 kg and three wheels it will fall under "motorcycle" regulations in most countries, AFAIK at least in U.S. and Russia. Also it doesn't need _metal_ crumble zones for crash with another solar vehicle -- plastic crumble zones will do the trick for 200 kg cars. Your crumble zones in your car will never protect you in the crash against 18-wheeler, why mandate crumble zones against the same weight difference? Hell, there are tons of motorbikes rowing around the globe with NO airbags, crumble zones, seat belts and other measures, why these are not mandated to such ridiculous restrictions first?

          With all of this, the clear answer for future automobiles is either hybrid gas/electric, or hydrogen fuel cells powered by hydrogen from clean nuclear power plants.

          With hydrogen energy storage you'll depend on country economics and political situation in the world, like you do with petroleum. And with anti-nuclear craze you can't expect enough new power plants. We are still far, far away from building hydrogen supply stations everywhere, since we still do not have good hydrogen storage. And solar vehicle doesn't need these stations at all...

          It's possible to build usable solar car today. But public will never buy it because they want luxury and "safety" and they are willing to pay $$ for petroleum.

    • Why is everyone so interested in Solar power? Solar power is not gonna be the alternative fuel of the future, it just doesn't make enough power for pratical use. Fuel Cells and Hydrogen is the way to go.

      Yeah, right. Who needs wind turbines, lead acid batteries are the way to go :-)

      You can't compare solar power with fuel cells. Fuel cells are great for storing and transporting power. They actually do not produce power, because it's powered by hydrogen, which has to be produced in the first place using some other power source like nuclear plant, solar cells, wind turbines, thermonuclear reactors etc. And there aren't enough natural sources of hydrogen.

      • Exactly....


        The interaction of the Hydrogen and Oxygen that creates the power of the fuel cell would be irrellevant if not for a source of pure hydrogen.


        Until you find yourself a free source of pure hydrogen (good luck, I doubt one exists on this planet), you are going to be stuck splitting Hydrogen from water. More or less the converse of the same reaction that creates power in the fuel cell. Which, those that understand elementary physics would know, even if the process were super-efficient, you would need as much energy as is produced from the fuel cell, to split out the hydrogen in the first place. In reality, you would need more.

    • Probably not for transportation, but I can definitely see solar power being good fuel for certain things.
    • The question is not "why?", but rather "where?". Clearly, places that dont have alot of cars dont need alot of alternative fuel. Solar technology still has a ways to go, unless you want hot water, but at least some of the contestants in this race do attempt to improve the cell effeciency, I guess.
    • Ever thought about the problem where the Hydrogen for the fuel cell comes from? Fuell cells only store power. And you could use solar energy to produce the hydrogen through electrolysis.

      So the combination of the two together would be some real great renewable energy. Just think of it: Thousands of square miles of solar arrays in the Sahara, or some sunny place anyway, powering huge industrial style Hydrogen plants. Then the hydrogen for the fuel cells gets shipped into the whole world. That'd be cool, huh?

    • Yeah, fuel cells are great, but where do you get the hydrogen? And once you get it, how do you distribute it? We currently don't have a really safe and efficient way to manufacture, store, and distribute free hydrogen in mass quantities.


      Using electrolisys of water to generate hydrogen is prohibitavely expensive -- how do you generate the electricty? Most current commercially-available fuel cells use a pre-processor to electochemically strip hydrogen from hydrocarbons. This is good because it is much more efficient than a traditional IC engine driving a generator, however it still has many of the same drawbacks -- it relies on a non-renewable resource and it emits greenhouse gasses (C02).


      IMHO the most practical short-term approach is to improve the techniques for generating methane from biomass. In order for this to work on a commercial basis, the cost of producing biomass-generated methane would need to be close to the price of tapping fossil methane sources. However, any commercial biomass technique is amost definately going to require the use of genetically-engineered microorganisms, which raises a bunch of other issues.

  • The paradox of solar-powered cars (Score:3, Insightful)

    by vlad_petric ( 94134 ) on Sunday November 18, 2001 @01:49AM (#2580368) Homepage
    In order to be acceptable from a consumer's point of view, such a car would have to have batteries ... Even in a desert you still wouldn't want to be limited to day-only driving.

    Batteries on the other hand are very heavy. They account for more than 50% of the weight of a regular electric car. The energy required to move the batteries makes such a solar-powered car infeasible.

    As mentioned in another post, most of the teams only improved on aerodynamics & weight. So, I'm asking: what's the point of this competition ?

    The Raven.
    • The point of the competition is not the solar power aspect, but the engineering of the project as a whole, the balancing cost and performance. It gives college students hands-on experience building and designing, gives companies and universities media exposure, and is fun.

      Learning and fun have always been the reasons for any competition. What did you expect was the reason?

      KingPrad

    • Just so you know, the solar cars all have batteries. Charge 'em up before ya race, and during the race you can put excess energy in the cells, in addition to the energy from braking.
    • Lithium ion technology is something that is still fairly new to consumer products, but it has been around in the "experimental implementation" field for a long while.
      the UMR Solar Miner III seen here [umr.edu] can do close to 600 miles on a 68Kg LI+ battery pack, whereas a traditional lead-acid battery pack that would give us the same milage would be more than twice the weight

  • solar engineering, a balancing act (Score:3, Interesting)

    by darkweb ( 468082 ) <darkweb4@hotmail.com> on Sunday November 18, 2001 @02:39AM (#2580436)
    first, a shameful, kowtowing plug: http://solar42.umr.edu [umr.edu]

    solar car design and raycing is (for us uni and high-school persons)is primarily an endevor of engineering. you can't always splurge on the 34% efficient space-grade cells. sometimes you have to determine that you don't have the money, and you'd rather have a decent car overall than a boffo solar array on a wooden crate. if an engineer works hard enough at it, and has the right insight at the right time, many good things can happen...independent of the almighty buck. at UMR we have pretty good funding (how much is for me to know, not you all ;) ), but when we design a car, we know that there are teams out there that have 3 times the funding that we do. So, rather than sacrifice our budget for the nifty "one-item" improvements, we spread costs out to balance improvements. I would say that batteries, solar cells, and the motor are the three big ticket items in a solar car. sacrificing the quality of the motor and battieries that you can purchase for a really high efficiency solar array is bad engineering. in this way, solar raycing is kind of like taoism, everything must be in balance
  • Bunches of comments are being posted regarding gasoline engines are faster, fuel cell are the future, solar is impractical, etc. Totally correct. Totally off-topic.

    These vehicles are not cars in any conventional sense of the word. They are an engineering challenge to see who can best balance weight, aerodynamics, PV efficiency and energy storage. They have to make strategic decisions. Last year the University of Missouri - Rolla team actually benefited from cloudy weather because they had a package that ran further on stored energy than the other cars. This actually slowed them down a bit compared to the other cars when it was sunny.

    I think its great to get a bunch of engineering students together in a friendly competition.
    • Actually (as I've pointed out before), the technology that is being used in these cars is being transferred into the mainstream. Things like Wheel Motors of efficiency ~96%, among other things, are making moden cars a lot more efficient.
  • The big problem is keeping up with solar cars that don't stop for fuel.


    Well it shouldn't be that hard. In most situations, the fuel outlasts the drivers.
  • ... is if they race 3000km across the UK.
  • any rules that prevent using the solar panels as wind sails as well? Dual powered car, with solar and wind, will probably be a little more promising.

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