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Transportation Earth Power Technology

Solar Powered Car Can Get Close To 60 mph 119

Posted by timothy
from the australians-still-on-about-transportation dept.
Jason Sahler writes with this excerpt from Inhabit: "The World Solar Challenge across the Australian outback is coming up, and we're already seeing some truly incredible vehicles going for the gold. Take the Bethany, a solar powered vehicle designed by Cambridge University students. The vehicle is capable of achieving close to 60 miles per hour. Doesn't sound too impressive? Try doing it by using the power required to run a hairdryer."
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Solar Powered Car Can Get Close To 60 mph

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  • by InsaneProcessor (869563) on Tuesday April 07, 2009 @11:34AM (#27490099)
    And I don't think my entire family will fit either.
    • by Thanshin (1188877) on Tuesday April 07, 2009 @11:37AM (#27490167)

      does it do in the crash test? And I don't think my entire family will fit either.

      Are you looking for a car? Or for an alibi.

    • by Nutria (679911) on Tuesday April 07, 2009 @11:50AM (#27490379)

      And I don't think my entire family will fit either.

      Or groceries or luggage, or run on a cloudy day.

      Solar auto challenges should be viewed as nothing more than useful engineer training that serves no immediate practical purpose, just as having my CompSci prof give me a large Senior Project, that I haven't used in my professional life, but gave me a solid foundation on which to grow.

      • Solar auto challenges should be viewed as nothing more than useful engineer training that serves no immediate practical purpose...

        Disagree.

        Granted solar power is not suitable for actual every day transportation in most parts of the world, a great deal of the engineering of these cars will move into the mainstream - and sooner than you think. As fuel gets more expensive, cars will have to get much lighter, much more aerodynamic, and have much lower rolling resistance. Many of them will use battery or hybrid power systems, and regenerative braking will become commonplace. Solar cars are pioneering all these technologies.

        • by MasseKid (1294554)
          I beg to differ. There are companies that are developing ways to make more fuel efficient cars. Those budgets combined are on a different order of magnitude than the budget a group of college kids get to hobble together a car. Those companies are the ones that are shaping the future. I don't think ANY of the solar cars are using regenerative braking as the weight cost would never be repaid as these cars don't stop but once a race. Furthermore you make a critically bad assumption. Fuel does not have to
          • by Nutria (679911)

            with a good battery, i.e. hydrogen, you can make power more efficiently at a power plant and the total energy cost can decrease.

            Except that we (only in the US, or does it happen all over the world?) lose something like 50% loss from transmission.

            What I, IMNSHO, think we need are smaller NG nuke plants closer to population centers. Higher efficiency thru less transmission loss, but more sites to protect from Bad Guys.

            • by MasseKid (1294554)
              Wiki says... [QUOTE=wiki] Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. [3] [/QUOTE] :shrug:
          • by topnob (1195249)
            What they don't have to brake when going around corners... wait I think they do! :D
        • by Colin Smith (2679) on Tuesday April 07, 2009 @03:42PM (#27494385)

          Using NiMH batteries.

          http://en.wikipedia.org/wiki/Solectria_Sunrise [wikipedia.org]

          http://www.sunrise-ev.com/ [sunrise-ev.com]

          Everyone else is just re-inventing the wheel.

          The best place of solar panels is on the roof of your house, charging up a battery bank you can use to charge the car when you park it.
           

          • by rah1420 (234198)

            And where [ev1.org] are those NiMH batteries now? Hmm?

          • by Nutria (679911)

            The best place of solar panels is on the roof of your house, charging up a battery bank you can use to charge the car when you park it.

            Ain't that the frickin' truth! My house's roof has a huge rectangular surface pointing due south that I'd love to do nothing more than cover with solar panels.

            But

            1. they are expensive,
            2. I live in hurricane territory, and
            3. I'd have to seriously trim back a couple of trees to eliminate that damage vector, and cutting down CO2-eating, O2-producing, heat-absorbing shade trees just t
        • by evilviper (135110)

          a great deal of the engineering of these cars will move into the mainstream - and sooner than you think.

          What new engineering is needed for a normal car?

          Electric motors have been 99%+ efficient for a very long time.

          Low rolling resistance merely means a STIFF tire. You'll never see lower rolling resistance than solid steel train wheels, which have been around forever. For road traction, a thin layer of a gripping material, like tire rubber, is all that is required for performance and safety (if you don't mi

          • What new engineering is needed for a normal car?

            90% of the weight, for a start. Less weight means better performance per unit power. Less weight means lower forces on the tyres, thus smaller contact patch for the same tyre pressure, thus lower rolling resistance without loss of comfort. Less weight means better hill climbing.

            We can't afford to be making cars out of steel any more.

          • by talz13 (884474)

            Any amount of power will eventually accelerate you to any speed.

            Not to the speed of light it won't

        • by geekoid (135745)

          "...- and sooner than you think."

          So not immediate? like the poster said.

          These solar cars do not pioneer any of that in any practical way.

    • by Alioth (221270) <no@spam> on Tuesday April 07, 2009 @01:39PM (#27492385) Journal

      It's a racing car. Your family and your groceries won't fit in a Formula 1 car or Indy car either. It's not supposed to be a family car or anything approximating that, it's for racing.

    • Re: (Score:3, Funny)

      by Endo13 (1000782)

      And I don't think my entire family will fit either.

      Imagine a beowulf cluster of them!

  • by peterdaly (123554) * <petedaly.ix@netcom@com> on Tuesday April 07, 2009 @11:34AM (#27490109)

    This is very interesting technology. These solar races really produce odd looking vehicles. Three wheels makes sense in terms of rolling resistance, but I can help but think what might happen if it needed to take a turn fast.

    Programs like this are great, and help push the technology envelope. Although it's neat that it can hit 60Mph...the article really does not have much real information in it.

    I hope to see some of this technology filter down into production cars. I've always wondered how much power could result from the sunlight hitting the roof of my car all day long when I'm at work. Seems like there is potential missed opportunity there.

    -Pete

    • by Thanshin (1188877)

      I've always wondered how much power could result from the sunlight hitting the roof of my car all day long when I'm at work. Seems like there is potential missed opportunity there.

      I've always wondered how much power could result from the sunlight hitting the road my car is on most of times it actually needs power.

    • The sun hitting car during work made me think of my grandfather and his solar power lunches. He would put food in a heat proof container and stick it on the the dash of his car when he worked (vine dresser in Californians Central Valley) and every day he would get a hot lunch. Now when I camp I put my cooking water in the sun so it takes less time to boil later...I had a point, but it's lost now.
      • by Mprx (82435)

        You may be interested in this:

        http://solarcooking.wikia.com/ [wikia.com]

        Solar cooking isn't practical in every climate, but when it works it can be very effective.

        • by xaxa (988988)

          I've seen solar cooking work in England, just from a friend making a solar oven out of a box, aluminium foil and black paint (IIRC).

          No doubt it's a lot quicker in southern California. (And in England it's not going to work too well in the winter, or on dull days.)

    • by cplusplus (782679) on Tuesday April 07, 2009 @11:44AM (#27490281) Journal
      I've had the same thought. I'd love to be able to drive to work in a plug-in vehicle of some sort, park the car in the sun all day and let it passively recharge, and then drive home using that free power. The only thing the sun does for my car now is make the interior too damn hot (even with window tint and a sun shade).
      • Re: (Score:3, Informative)

        by Rei (128717)

        Sorry, but not with current physics.

        A typical streamlined EV, like the Volt, the MiEV, or the Roadster, will use about 200Wh/mi. Let's go with 220Wh/mi wall to wheels, since some is lost in charging. Let's assume a very efficient panel (20% *after* accounting for the cells not all fitting perfectly together) and a large, flat area (2' x 4' ~= 0.74 square meters). Let's say that it's perfectly sunny (1000W/m^2), there's no shade, and let's be optimistic and say that the cosine-weighted average angle of th

        • a large, flat area (2' x 4' ~= 0.74 square meters)

          If you're going to be crazy optimistic in your other assumptions, you might as well assume a flexible solar cell car cover, with 3 times that area.
          Or you could carry a folding 4x8 canopy and go all the way to 15 miles.

          • by Rei (128717)

            The more curves the panels go over, the less light they'll capture.

            As for a canopy, yes, it makes more sense, but still not as much sense as just having the panels on your roof. Not to mention that most flexible cells aren't as efficient as rigid ones. Nor will that canopy be particularly lightweight or easy to handle -- just the opposite.

        • by Carnildo (712617)

          A typical streamlined EV, like the Volt, the MiEV, or the Roadster, will use about 200Wh/mi. Let's go with 220Wh/mi wall to wheels, since some is lost in charging. Let's assume a very efficient panel (20% *after* accounting for the cells not all fitting perfectly together) and a large, flat area (2' x 4' ~= 0.74 square meters). Let's say that it's perfectly sunny (1000W/m^2), there's no shade, and let's be optimistic and say that the cosine-weighted average angle of the sun to your car is 50 degrees over th

          • by Rei (128717)

            Well, that's a completely different proposal, now isn't it? :) On the car, you're limited by available flat surface area. And do you know how heavy and complicated of a proposition that is you're talking about -- a portable support frame that'll stand up to whatever winds or whatnot come along, with that much solar cell material? And if your answer to save weight (ignoring the frame) is "thin film", cut your efficiency in half.

      • by Luyseyal (3154)

        I want to drive an electric golf cart to the "highway", get on a high-speed train of other golf carts, push a button to make it let me off near my destination, and then drive the cart to my job. And do the reverse on the way back.

        -l

    • Re: (Score:3, Interesting)

      by hedwards (940851)

      If you need to turn that fast you're probably screwed anyways. The friction on the front tires hasn't been the limiting factor for quite some time.

      The much bigger problems are weight distribution and the rate at which the wheels spin with respect to each other. Hence the addition of http://en.wikipedia.org/wiki/Electronic_stability_control [wikipedia.org] for more information.

      And with only 3 wheels, that latter concern is easier to deal with than with the extra wheel.

    • Re: (Score:3, Interesting)

      by Rei (128717)

      This is very interesting technology. These solar races really produce odd looking vehicles. Three wheels makes sense in terms of rolling resistance, but I can help but think what might happen if it needed to take a turn fast.

      Just because it's three wheeled, or because it's this specific car? Three wheelers can be extremely stable [autospeed.com].

      I've always wondered how much power could result from the sunlight hitting the roof of my car all day long when I'm at work. Seems like there is potential missed opportunity there

    • by Grishnakh (216268)

      While I think we definitely need to do something as far as our transportation infrastructure, these solar-powered cars seem about as useful to me as radio-control cars (the kind that are 1-2 feet long) which can go 60mph. 60mph is not a great achievement, since it's easy to do that with a small R/C car running on a battery. Of course, someone will probably say a 40-pound R/C car can't carry a human passenger, and that's true, but that R/C car really has about the same utility as one of these solar-powered

  • No, not impressed. (Score:5, Informative)

    by gblackwo (1087063) on Tuesday April 07, 2009 @11:36AM (#27490143) Homepage
    Most of the North American Solar Challenge vehicles and World Solar Challenge Vehicles easily exceed 60 mph.

    I work on Purdue's Solar team and have first hand experience with these vehicles on the highway.

    www.PurdueSolar.org
    • There ain't much sun in Cambridge.
    • by oneiros27 (46144) on Tuesday April 07, 2009 @11:58AM (#27490505) Homepage

      I was on the GW solar car team more than 10 years ago -- we could do 60mph back then, so I'm not impressed, either.

      The important factors included: how much sun is there are the time, are you willing to drain the batteries, and are we going uphill?

      If you've got good sun, don't have a screwed up array like we did in the '95 Sunrayce, and are willing to drain your batteries, it's easy to go over 60mph. And if you're going downhill, it's even easier.

      Of course, that year they decided to put the finish line at the top of a mountain, and we had mostly clouds for the last few days, so just about everyone showed poorly overall.

  • Sponsorship (Score:2, Insightful)

    by ickleberry (864871)
    Those HP Logo's could have been solar cells and it would have actually got to 60 rather than close to it
  • Big whoop (Score:3, Interesting)

    by djupedal (584558) on Tuesday April 07, 2009 @11:46AM (#27490315)

    >"Try doing it by using the power required to run a hairdryer."

    Hair dryers pull 1000~2000 watts, right? That is a ton. Try having only a few watts to work with...on Mars. [xs4all.nl]

    "The transmitter on the lander has a broadcast power of about 14 watts, says Callas. For comparison, the beacon on the Mars Global Surveyor, which is currently in orbit 380 kilometers (228 miles) above the surface of the Red Planet, is weaker -- only 1 watt. Boding poorly for the mission is the fact that this week the sensitive Dish detected the weaker signal from the surveyor, but not the stronger signal from the lander.

    But the main problem is the weakness of the signal. And signals weaken as they traverse the roughly 300 million kilometers (about 180 million miles) from Mars to Earth. "We expect a signal hitting the Dish to be something of the order of one billionth of a billionth of a milliwatt [one-thousandth of a watt] of power," says Callas. "It's extremely tiny. This is equivalent to listening to a cell phone from Mars.""

    • by Thanshin (1188877)

      "We expect a signal hitting the Dish to be something of the order of one billionth of a billionth of a milliwatt [one-thousandth of a watt] of power," says Callas. "It's extremely tiny. This is equivalent to listening to a cell phone from Mars.""

      "An extremely tiny cell phone." says Callas "With both hands tied to your back. And a hearing problem. And a crappy telco that hangs the calls if you speak the word "Midget"."

    • by ivan256 (17499)

      Exactly. Want your average engineering student to build something that can hit 60 mph on 1000 watts? No problem.

      The question is.... How long does it take to get to 1000 watts.

      I've seen some pretty impressive cars powered by 2HP steam engines. They could go really fast.... But it took them several minutes to accelerate to top speed.

      • by ivan256 (17499)

        Duh. Think-o...

        "How long does it take to get to 60mph"....

        I previewed, and it looked right... Then as I browsed away from the comment the "oh-shit" kicked in...

    • Re: (Score:3, Funny)

      by R3d M3rcury (871886)

      Hair dryers pull 1000~2000 watts, right? That is a ton. Try having only a few watts to work with...

      You had a few watts?! LUXURY! Why, when I was a boy, we had to generate our own electricity by walking up hill to school! Both ways!

      But try to explain that to the kids today...

    • by MasseKid (1294554)
      Umm... that's transmitted power. That has nothing to do with how much energy the mars rover is using. Hell, it's using around 150 watts to generate that 14 watt transmition signal. 14 Watts is what you would expect a small dish to transmit from earth's surface to a satalite.
  • 60mph Average (Score:5, Informative)

    by zlexiss (14056) on Tuesday April 07, 2009 @11:46AM (#27490321)

    I think (the article is badly written) that the key development is that this car can average almost 60mph. 60mph burst speeds are pretty easily reached in many solar cars. I remember doing about 65 mph back in 1993 in our cars (Dartmouth College's Sunvox I and IV)

    • by drinkypoo (153816)

      That's actually pretty incredible, but it would be more relevant to know how useful solar can be in the case of a feasible production vehicle. Don't forget to park facing the Equator (with variation for time of day) to gain maximum insolation! :) So far I think the best application is a golf course; all the carts could have a solar charger on them, and you could tie them all to the grid. It doesn't have to be expensive, if it's built in.

    • 60 mph on average isn't anything new either, the Dutch University of Delft team did an average of 103 km/h during the 2005 Solar Challenge with their Nuna [wikipedia.org] car. The solar car they will use this year is two generation further, so probably will go even faster.
    • by dajak (662256)

      The Dutch 2001-2007 winners of the World Solar Challenge met 60 mph in 2003 and exceeded it in 2005 on average over a 1,877 miles distance. 60 mph is the speed to aim for to have a chance of winning (contingent on weather, and being forced by circumstances to brake).

      Perhaps the article is only trying to say that a UK university is participating with a competitive car in the World Solar Challenge.

  • by onion2k (203094) on Tuesday April 07, 2009 @11:46AM (#27490323) Homepage

    Actually going fast is pretty easy so long as your aerodynamics are sound. All you need is enough energy input to counter air resistance and friction from the wheels and you can maintain whatever speed you like. The difficult bit is accelerating to a high speed quickly. It'd be easier to wait until people get over wanting to go fast than design a solar vehicle that can accelerate from a standstill anything like a petrol car.

    Fortunately I can see that happening. As the price of driving goes up people's priorities will change.

    • Re: (Score:3, Interesting)

      by prefect42 (141309)

      But surely systems like KERS show that with only a small weight penalty (from around 25kg), and a decent amount of power (~80bhp), you can already get there. Now as long as you don't need to be using that often, and can simply clutch it out while not using it, it's just 25kg of dead weight while trying to be efficient.

      This is assuming that you've got another much more efficient lower powered motor for the rest of the time.

      25kg just isn't such a huge weight to carry in any vehicle intended to carry 2+ peopl

    • by drinkypoo (153816)

      Actually the optimal aerodynamic characteristics are different at high and low speeds. Also going fast is a lot more challenging because you ask a lot more of the tires, and all of these crazy-high-mileage vehicles have special tires which are either very expensive and short-lived, or have very little traction compared to what's on a typical passenger car like a Ford Taurus or Toyota Camry.

      • Re: (Score:3, Insightful)

        by Rei (128717)

        Yeah. Note what happens when you try to take these sort of concepts from "crazy hypercar" to "usable vehicle". Compare, for example, Pac Car II [web.psi.ch] to the Aptera 2e [aptera2e.org]. Same basic design philosophy, but the 2e has to be usable on city streets, hold two passengers and a good amount of cargo comfortably, be practical to mass produce, have proper acceleration and range, and in general have the amenities and safety people expect in a car. And the net result is that you go from a drag coefficient of 0.06-ish to one

    • by Dunbal (464142)

      So one day someone will come up with a hybrid solar/electric vehicle, that uses stored energy to accelerate, and solar power to cruise/extend the range?

    • by khallow (566160)

      Fortunately I can see that happening. As the price of driving goes up people's priorities will change.

      Or unfortunately as most of humanity would see it. Remember time is valuable too. And I can't help but notice that the societies in which peoples' time isn't very valuable tend to be societies in which people aren't very valuable either.

    • Speaking of aerodynamics, it looks as if a good puff of wind will flip that car like a pancake. When I lived in Los Angeles, microbursts would occasionally knock over concrete benches at bus stops. This car doesn't stand a chance.
  • I'm an electric car.
    I don't go very fast,
    Or very far.
    And if you drive me,
    People will think you're gay!

    (Solar cars are still electric, it applies dammit!)

    • by Culture20 (968837)

      (Solar cars are still electric, it applies dammit!)

      Obviously you've never seen a steam powered solar focusing array on wheels. Not everything is photovoltaics.

      • (Solar cars are still electric, it applies dammit!)

        Obviously you've never seen a steam powered solar focusing array on wheels. Not everything is photovoltaics.

        He hasn't, but have you?

    • by Rei (128717)

      That's [teslamotors.com] very [wrightspeed.com] insightful [lightningc...pany.co.uk] of [venturivolage.fr] you [hybridcars.com], you [shelbysupercars.com] know [autobloggreen.com].

  • I don't know, one could power a small country with the same power needed to run the Spaceballs hair dryer.
  • And go probably 100. The interesting thing is that having super lightweight cars is really what this whole engineering problem is about. That benefits not just solar power, but any power. If you can run a car off the 1kw, then, that would follow that you could run one off of a 1.4 horsepower engine. That would be roughly the same as what the Amish do, except they just use big horses, so maybe we should just go ask them for fuel efficient designs.

    • by averner (1341263)
      The heat and exhaust generated from the lawnmower engine would make it difficult to fit into similar dimensions.
      • by tjstork (137384)

        The heat and exhaust generated from the lawnmower engine would make it difficult to fit into similar dimensions

        I was thinking more horsepower-wise than actual lawnmowerness. I get the impression that the run of the mill lawnmower engine lacks a lot of the fuel efficiency technologies of their larger cousins.

  • It gets near 60 once the F-250 rear ends it and pushes it along.
  • Power source/Sun: at least 1.21 gigawatts. Check.
    Speed: 88 miles per hour: Over 2/3 of the way there.
    Power conversion to usable form: Nowhere near 1.21 gigawatts available.

    I guess I'll have to postpone my time travel a bit.

  • Let's do the math (Score:3, Informative)

    by Ancient_Hacker (751168) on Tuesday April 07, 2009 @01:07PM (#27491791)

    Let's do the math on this one.

    A hair dryer draws around 750 watts, which is a convenient number too, as that's about 1 horsepower. Let's assume the electric motor is 100% efficient too, just for simplicity.

    So you're saying the car can do 60MPH on one horsepower.

    That's quite doable with a very aerodynamic design and low-friction tires.

    But the hill-climbing ability is mighty weak.
    One horsepower can lift 550 pounds one foot per second.

    So if this vehicle and rider weight 550 pounds, it's going to slow down to 70.7% of 60 MPH if it encounters a hill with a 60 foot rise per mile, just a bit under 1% slope. A 3% slope is going to slow it to a crawl. Not too good anyplace but Kansas.

    And no, you don't get it all back on the downhill slope.

    • Re: (Score:3, Informative)

      by Rei (128717)

      A hair dryer draws around 750 watts

      That's one weak hairdryer.

      it's going to slow down to 70.7%

      If there were no batteries to average out the ups and downs.

      • A hair dryer draws around 750 watts

        >That's one weak hairdryer.

        Your typical bathroom outlet starts getting hot at anything over ten amps, 1200 watts, which is not even twice as much. And since the hair-dryer was a simile to begin with....

        it's going to slow down to 70.7%

        >If there were no batteries to average out the ups and downs.

        Batteries have to be carried uphill too, so you gain some and you lose some.

        • by Rei (128717)

          A hair dryer draws around 750 watts

          You know, you could have at least bothered to google "hair dryer" and "watts" [google.com]. The first link you'll find is reviews for hair dryers in the 1200 to 1800 range. My hair dryer at home in my downstairs bathroom is 1600W.

          Batteries have to be carried uphill too, so you gain some and you lose some.

          That doesn't change the fact that they average out demand differences. They're a *net loss*, but they can eliminate the changes in speed that would otherwise occur on slopes.

          • There is no point in arguing about wattage of your hair dryer. We're talking about the power available on a solar vehicle, not the maximum power of some rather poorly chosen simile.

            The real point is that a solar powered vehicle is only going to have one or two horsepower available at best on a very sunny day-- fine for a bicycle or rickshaw but not so good for the kind of vehicle most of us need.

    • So if this vehicle and rider weight 550 pounds, it's going to slow down to 70.7% of 60 MPH if it encounters a hill with a 60 foot rise per mile, just a bit under 1% slope. A 3% slope is going to slow it to a crawl. Not too good anyplace but Kansas.

      Sweet! I live in Kansas. I got to get me one of these!

    • by daybot (911557) *

      A 3% slope is going to slow it to a crawl. Not too good anyplace but Kansas.

      I live in Cambridge, where this thing was built, and I can tell you that for us this restriction is not a problem - the whole city is totally flat. That's why 25% of the population cycles to work. The thing that doesn't make sense is that it is a solar powered vehicle - not much sun here. Rain powered, or if you could feed it foreign language students - that would be ideal!

  • What they don't mention: you have to get so close to the sun that the tyres melts.

  • That car won't be passing any crash tests soon. I still appreciate it as a fine piece of engineering, though.
  • So, briefly skimming the article, it's about the solar challenge.
    60 MPH is squat.
    Previous winner Nuna 4 [wikipedia.org] did almost 90, as it had a top speed of 142 km/h (or 88MPH)
    The version before that did an average of 63.8 MPH for the entire race. (after that they changed the rules)

    So what's the news value of this?
    have the rules changed for this years solar challenge?

  • But untill these cars are mainstream, I WILL put large, thick pieces of dark paper on top of people's panels while they're parked to piss them off. You have my word.

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