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Electric Cars and Their Discontents

The most hotly contested issue raised by yesterday's post about the lithium-ion battery-powered Tesla roadster is only tangentially related to the car itself; instead, it's the energy generation and storage required for electric cars more generally to operate. Read on for the Backslash summary of the conversation, including several of the comments that defined the conversation.

A typical comment about the global impact of switching from gasoline to electric cars on a wide scale comes from reader dbIII, who comments:

"Until something replaces Coal power plants as the main method of generating electricity, you're just replacing one evil for the other."

"With better battery storage it doesn't matter much where the electricity comes from and when - the car could be charging up with solar power in the carpark in the day or with wind when it is blowing, or off-peak when the base load stations are running as low as they can but no-one wants to use the electricity."

"Battery power isn't about saving energy anyway, it's often about shifting the pollution to a big facility that can handle it instead of having heavy pollution control equipment to move about. The first hybrid car I saw, back in 1987, embodied this principle and was designed to work at an underground mine. Above ground it ran on fuel, but below ground you wanted to minimize the air pollution as much as possible so it ran on batteries."

The continued existence of the earth as a habitable planet aside, what about the car itself, and in particular its power source?

Jah-Wren Ryel has a quibble with the terminology used the linked article, writing

"This car is not a true Tesla Car. If it were, it would have no batteries at all. Instead it would gets it energy from some kind of wireless source like microwave power transmission or even the Earth's magnetic field."

Many readers worried about exploding batteries; glowworm was "left wondering if this car is involved in an accident if the batteries will vent like the recent Slashdot articles suggest. Exploding Dells, fires on planes, and soon at an intersection near you... cars venting more flame than the Batmobile."

Reader nSinistrad_D provides reason to think such explosions are unlikely:

"Looks like the company that is manufacturing the batteries has replaced graphite with a 'Lithium Titanium Oxide' that they've tested and claim doesn't have the smoking, venting, or explosive problems of normal lithium ion batteries. Here is a link to a rather informative article about the battery technology that will be used in the Tesla. ... I mean, based on the stuff I've read about the founders of the company and a lot of the people who have invested in it (i.e. Elon Musk, Larry Page, Sergey Brin, etc.) I feel I'll wait and see before passing any judgement."

Reader artifex2004 is skeptical: "Here in Texas, where I suspect temperatures exceed battery design, I think this idea will bomb spectacularly. Seriously, though, Li-ion? I shudder to think of how those will get disposed of, eventually."

And Reader Moofie has a tongue-in-cheek solution if the batteries ever go critical: "Maybe you could design a clever little nozzle to get a boost from your on-fire battery packs. That'd be AWESOME."

It's not just safety, of course, that matters to drivers, but practicality for other reasons:

Reader iamlucky13 writes: "15 minutes on the charger might get you another 15-20 miles. And 220 volts at 70 amps is a pretty hefty 15 kilowatts, so to have a dozen cars sitting at the local McDonalds charging is going to be draining about 180 kW from their coinpurse. That is a serious amount of juice. Also, I'm skeptical that you'll be getting 250 miles at 70 mph. If I remember right, electric motor efficiency and power typically increase with load, but fall off with speed, which makes them awesome for say, a 0-60 run in 3 seconds, but marginal at best for high speed cruising. That 250 mile range estimate is probably at significantly lower speeds."

"Big rigs generally run around 5 mpg, but it varies quite a bit around that number depending on the truck, the load, and the speed. Few truckers drive at the most efficient speed because it increases the labor costs significantly."

"If you're suggesting running commercial trucks on electricity, forget it for the foreseeable future. It's definitely been considered. Not only is there the conflicting speed issues I mentioned above, but you run up against the energy density limitations of batteries fast. Assuming the numbers from the article are correct (I doubt it...something isn't quite adding up according to my gut) and unrealistically taking the charge/discharge at 100% efficiency, it's storing up 194 MJ. Gasoline holds about 120 MJ/gallon, so the 1000 pounds of batteries (according to the Tesla website) are equivalent to about 1.5 gallons of gas (6.3 pounds/gal). Divide that an efficiency of around 30% and you've got a 32:1 energy density ratio in favor of gasoline. For a truck to haul the equivalent of 150 gallons of fuel (actually diesel, not gas, but close enough), it would need about 30,000 pounds of batteries. But then you have to go farther and take into account that 2/3's of its cargo capacity has been replaced fuel, so you need to make 3 times the number of trips. And you've got a lot of trucks either sitting idle recharging or having their 30,000 pounds of batteries swapped out every few hundred miles."

"Obviously these are really rough numbers, but other engineers have already looked at the idea in more detail and rejected it."

"I'm not trash-talking the Tesla. It looks like a lot of fun, but like all sports cars, it's a toy and not a good comparison for commercial trucking. Most of a car's weight is itself, be it gas or electric. Most of a truck's weight is it's cargo."

"For the record, I think electric can work extremely well for short range commuting (5-10 miles on city streets), but if you travel far, you'll realistically be looking at gas."

As to the exact number of batteries in the car, reader wbean provides a good reason why it should be exactly 6831: "The motor is going to need a lot higher voltage than a laptop. This means that the batteries have to be organized in series/parallel banks. 6831 is a plausible number since it is 23 x 11 x 3 x 3 x 3. This gives you a lot of flexibility in arranging the banks. You could have 99 banks of 69 batteries in series, presumably giving you something like 345 volts. That sounds about right for a DC motor."

Of course, battery technology is the real crux of the issue; balancing safety, weight, volume and energy density is a tough problem, and as reader loose electron puts it,

"Whoever comes up with a significant advance in battery technology will . Li-Ion batteries have excellent amp-hour ratings for their size, but like all other batteries are still pretty limited."

"Acceleration/Torque for electric cars is not a problem. High performance capabilities are there if you want them. However, you are playing battery energy against performance against distance, and all electrics, or fuel-electric hybrids have been designed to be 'green' in their approach. (Any Hummer owners want an environmentally aware vehicle?)"

"Right now the weakest link in many electronic systems is the energy source. A good solution there and you can be a very wealthy person."

hotspotbloc suggests " a different type of hybrid," one with:
  • "enough batteries for ~50 miles.
  • a small (100cc) biodiesel engine running at a fixed and preset RPM connected to a small generator. The engine would be set to run at the peak of its power curve.
  • a small ~10L fuel tank
  • and
  • an AC charging circuit"
"This would allow the driver to run on electric most of the day and charge on the road when needed. One could also use a gasoline engine instead of biodiesel and still see big fuel operating savings since some wall recharging would take place. It would also greatly decrease the number of batteries needed."

"This is a really old idea. I saw something like this (on a much larger scale) on an USCG cutter (WLB-389) that was built in 1943. Two diesels -> two generators -> one electric motor. Worked great and it could double as a light ship."

Finally, several readers' comments focused on the merits of the particular electric car, rather than only as the embodiment of its constituent technologies.

fermion was one of a handful who talked about the car as a sportscar per se, writing:

"I would wager that this vehicle is more like a Lotus Elise, or a Corvette, or even a S2000, all of which can be had for under 50K. Any performance benefits over those sports cars can be attributed to the natural advantage of this car, namely that you can go from 0-60 without switching gears, and it is easier to get it perfectly balanced without an engine. Anyway, The true test of a sports cars, as opposed to just a fast car, is the handling, which was not mentioned in review. Without proper handling, it becomes a Mustang at 30K."

"Which is to say we are still in the same world, in which low volumes and other issues cause electric cars to be 50%-100$ higher than traditional cars. All that seems to have happened here is that an electric car has been targeted to the high end market and priced accordingly. It is kind of like taking the hummer, putting a cheap truck base on it, calling it an H2, and pretending that it still has the dubious value of the original."

"Oh well, I suppose if they can build a sedan for 35K I would be impressed. We would also have to look at maintenance cost of the vehicle, which would be dominated the battery replacement. A sports car car easily run 20 cents/mile in maintenance. Knowing that laptop batteries can only handle a couple hundred charge cycles, one can image where the long term maintenance cost could approach three or four time that amount."

"I wish we had electric cars. I think the technology is there, and the pricing could be reasonable. But even companies that could be using the electric car to revive themselves, for instance Mazda and Ford, still seem to be married to the antiquated internal combustion engine."

ChronosWS largely agreed with this, writing that "cars like the Porsche Carerra and the Bugatti Veyron (mentioned in a related article) are consummate sports cars -- they exemplify not only speed but styling, handling and quality expected of a car with their price tag. Cars such as the Corvette, especially the most recent incarnation, do so relatively inexpensively. But regardless, 0-60 acceleration is not the most important statistic, and often isn't an important statistic at all except to people who don't know better (I refer the undereducated to the more useful 0-100-0 or 0-150-0 tests, as well as relevant agility tests such as emergency lane change, slalom and skid pad.) Electric cars will be desirable when they meet the following conditions met [by] existing cars:"

  • "price (under 30k)
  • features (styling, interior, gizmos)
  • convenience (fueling in under 5 minutes)"
"This car does not appear to meet any of those."

Thanks to all the readers who took part in the conversation, in particular those quoted above.

15 of 348 comments (clear)

  1. wow.. talk about naive by ScottLindner · · Score: 5, Interesting

    "Battery power isn't about saving energy anyway, it's often about shifting the pollution to a big facility that can handle it instead of having heavy pollution control equipment to move about. The first hybrid car I saw, back in 1987, embodied this principle and was designed to work at an underground mine. Above ground it ran on fuel, but below ground you wanted to minimize the air pollution as much as possible so it ran on batteries."

    That's really naive. Batteries allow for greater efficiency and decoupling between the power plant and the car. How much innefficiency is there in having lots of tiny little combustion engines zooming all over the place with a bunch of ignorant car owners (I imply we all are ignorant to some degree with our cars) compared to a couple hundred regional power facilities that can use whatever fuel and power generation necessary? They can change to new power and fuel types without affecting the auto industry and consumers. They also can be heavily regulated and monitored to make sure those couple hundred catalytic converters actually work and they are performing proper maintainence to make sure efficiency is maximized and pollution is minimized. I mean.. how many car owners actually care if their cars are a couple of percent off from max efficiency? How many will change their driving style to match the size of engine they bought to squeak out another two miles?

    How many of you have been behind a car that makes you gag and you can see the trail of soot in the air for a quarter mile behind it?

    People that use such sophmoric arguments are... well.. sophmoric.

    --
    Slashdot.. where people join together in deliberate ignorance.
  2. I'd like to see more of these by drewzhrodague · · Score: 4, Interesting

    I'd like to see more posts on Slashdot -- discussions distilled down into their component topics, some useful information, and a rehashed go at it again. I hope to see more of these.

    On the Tesla, I'd like to see more of those as well. Especially discussion on turbine/electric hybrids. Why are we still using rubegoldberg-styled piston-based engines, with so many moving parts? I would like to see something effective and efficient for my morning commute.

    --
    Zhrodague.net - I do projects and stuff too.
    1. Re:I'd like to see more of these by marvinglenn · · Score: 2, Interesting
      Especially discussion on turbine/electric hybrids. Why are we still using rubegoldberg-styled piston-based engines, with so many moving parts? I would like to see something effective and efficient for my morning commute.

      The last time I researched this, in fuel efficiency (work out per work in), the piston engine beat the turbine. In weight effiency (power out per weight engine), the turbine beats the piston. Turbines have less moving parts and can generally be less complex, but the materials and tolerances for those parts are more complex.

      If you distill all this down, what you come out with is that a piston is still the better choice for a car/truck, and the turbine is great for an airplane. The reason a turbine works in an airplane is because engine weight means much more to an airplane than a car/truck. It means so much more that it's actually worth losing the efficiency of a piston engine because you gain much of it back in not needing as much power because the engine is lighter.

      I'm putting my money on biodiesel, and maybe a hybrid made with a diesel engine. On the ground, my engine will have pistons.

      --
      The whores get mad when the sluts give it away for free.
  3. Why should the McDonald's pay? by Anonymous Coward · · Score: 4, Interesting

    Why should the McDonald's pay for charging up your electric car? There's no reason why someone who arrived at the McDonald's by foot be paying some cost of charging up someone else's car. The driver or owner of the electric car should be paying McDonald's (or whomever McDonald's subcontracts or franchises the electric car parking spot) for the electricity. I would expect that any parking spot that would support charging up an electric car to also have some way to charge the driver for money for the electricity, since the whole concept of an electric car is basically going to obsolete the notion of a gas station or e85 station or hydrogen station. Heck, this could even be marketed as a time saving scheme -- you no longer have to go to the gas station because your car will always be ready to go. Unless electric cars start using disposable or at lest removable batteries that can be changed quickly at a 'battery station' for long trips, there's no need to refuel for short-trips.

  4. Best Backslash yet.... by Chanc_Gorkon · · Score: 2, Interesting

    This is a GREAT use of Backslash and the post even had a different look to it.....

    Now on to my comments....

    We all should want electric cars. The reasons are is they are not just cleaner to operate, they are also cheaper to maintain. There are less moving parts in a electric car and even the parts that are similar also get less use. The brakes don't need to be used near as much because of the regenerative braking the motor does. There's also no belts and no transmission.....no oil changes! I want a car like this. Electric cars CAN be more reliable then ICE cars. Th eoli companies just need to look at buying up some electric plants!

    --

    Gorkman

    1. Re:Best Backslash yet.... by cayenne8 · · Score: 2, Interesting
      "We all should want electric cars. The reasons are is they are not just cleaner to operate, they are also cheaper to maintain"

      Well, if it is cleaner, I'm ok with it, but, that's never a concern of mine when I buy a car. It has to have good performance, look stylish and most of all, be FUN to drive!! And...it is fun to work on cars, even though it is a bit more difficult to work on todays car, say, vs the older 60's - 70's ones...a user can still get in there to tweak, change thing out...put performance parts on etc.

      I'd be concerned that with the new electrics, unless you are an electrical engineer...the shade tree mechanic will be a thing of the past. Self maintenance on todays car can be a $$ saver...on the new ones...will we HAVE to have all work done at the manufacturer since it is too complex, or too dangerous?

      --
      Light travels faster than sound. This is why some people appear bright until you hear them speak.........
  5. efficiency by SuperBanana · · Score: 4, Interesting
    Also, I'm skeptical that you'll be getting 250 miles at 70 mph. If I remember right, electric motor efficiency and power typically increase with load, but fall off with speed, which makes them awesome for say, a 0-60 run in 3 seconds, but marginal at best for high speed cruising.

    Electric cars are much more efficient compared to internal combustion engines- much of the inefficiencies and losses pale in comparison to ICE's. Turbines are around 40-45% (BIG turbines), and ICE's are about 30%. I don't have a figure handy for the current state of the art in electric AC induction motors, but it's very high, comparatively. Modern chargers are better, and modern battery packs are more efficient as well (ie how much juice is lost to heat during charging.)

    Battery pack technology is a big restraint; one poster in the old thread idiotically said "we don't need better technology, we need stations where you pull up and swap packs!"

    Wrong. 1)Lead acid batteries are pretty much the cheapest W/$, but they are HUGE and they weigh so much the vehicle suspension has to usually be modified; they also don't last very long unless well taken care of. NiMH batteries are superior in many ways, except the current patent holder on NiMH packs won't allow companies like Panasonic to sell large NiMH packs for cars. Busses, great, sure. Mid-size sedan? Nope. Why? Probably they want to get nice plentiful royalties.

    NiMH is about to be completely eclipsed by Lithium Ion-like technologies. NiMH batteries loose a substantial amount of energy during charging to heat. At least two companies have figured out how to make LiIon more stable (able to withstand charging abuse, physical abuse like getting punctured with a giant steel rod, etc) and charge faster. One of the companies has packs that can be recharged in a few minutes, provided you have a powerful enough charger. Density is better, and they're finding cheaper materials to make them with.

    The other big advance has been with motor controller technology and brushless motors; before, people were using industrial-application DC motors which were brushed (which meant PITA maintenance- brushes have to be replaced, you have to have a blower to keep carbon dust from building up inside the motor, etc), inefficient, low-speed, and VERY heavy. Now you've got AC induction motors that produce a TON of power, and really nice inverter systems with regenerative braking and charging built-in.

    The main problem with electric cars has always been, and always will be, that nobody is willing to SHARE, and everyone is hideously greedy. Half the industry thinks they'll be the next Henry Ford; the other half thinks someone will figure out how to make a mass-produced vehicle and license their technology for astronomical prices (NiMH patent holders, Tzero with their integrated drivetrain.) Instead, the industry has skipped to LiIon, and Honda/Toyota/GM/Ford have done their electric drivetrain (for hybrid vehicles) development in-house, or worked with industry giants like Siemens.

    If you think the new crop of vehicles are different- look in the history books. Every 10-20 years someone gets a bunch of dough, and slaps together an electric vehicle for limited production. It has been going on since the 60's. Even big companies like Solectra have struggled. ZAP! has survived by diversifying, though they're pretty much gone now from the commuter car market now that Mercedes is re-assuming SMART importing in a year or two.

    Things seem a little different now though- technology has leap-frogged some previous barriers. The two remaining challenges are market adoption/acceptance, and power generation. MA tried to get a wind farm planted in the middle of a shallow bay, and the fucking environmentalists screamed blue-bloody-murder about everything little thing...from a small diesel tank (1000 gal) for maintenance equipment which was portrayed as the next Exxon Valdeez, to birds hitting the things, to sounds supposedly transmitted into the ocean that woul

  6. New "capacitor" batteries? by Yvan256 · · Score: 2, Interesting

    What about those new "capacitor" batteries?

  7. Measuring "Sporty" cars by DuckDodgers · · Score: 2, Interesting

    ChronosWS largely agreed with this, writing that "cars like the Porsche Carerra and the Bugatti Veyron (mentioned in a related article) are consummate sports cars -- they exemplify not only speed but styling, handling and quality expected of a car with their price tag. Cars such as the Corvette, especially the most recent incarnation, do so relatively inexpensively. But regardless, 0-60 acceleration is not the most important statistic, and often isn't an important statistic at all except to people who don't know better (I refer the undereducated to the more useful 0-100-0 or 0-150-0 tests, as well as relevant agility tests such as emergency lane change, slalom and skid pad.)

    Even skidpad, 0-100-0, slalom, and other tests don't paint the whole picture. The best way to judge is driving experience. The 2006 Corvette is a spectacular performance machine. But I've met people who just find the BMW 330 or the base trim Porsche Boxter (both substantially slower) much more fun to drive. People spending $100,000+ for a Porsche 911 or a Ferrari actually are getting more than just a badge. (Maybe not $150,000 worth in sport, but a lot.)

    0-100-0 (Accelerate from a standing start to 100 mph, then slam on the brakes to a full stop) tests will rule out things like a performance truck. The RAM SRT-10 can accelerate like a beast, but it is too heavy to stop in a short distance like a sports car. That's a good start. But a Mustang GT 500 will ace that test without offering a driving experience like a Porsche or Lotus.

    Slalom tests are weight towards smaller, narrower cars. If one car is 65 inches wide and the other is 82 inches wide, the former will have an easier time weaving around cones. It has 34 inches less of lateral movement to handle as it goes forward. That's a big deal around cones, but it may not reflect their comparative handling on a road course.

    At the end of the day, drive what you like.

  8. Wankel by Bob_Robertson · · Score: 2, Interesting

    Another problem is "rings". The rotor has flat barriers at the points of the triangle, and rings around the two faces of the rotor. These wear very quickly, and need to be replaced.

    Imagine if you had to have a "ring job" every 50k miles. That's serious $$.

    When Mazda introduced the rotary engine in America, the gas milage was better than what is listed here now, but it used an afterburner to reduce emissions rather than a catalytic converter. Just a data point. Even though they use catalytic converters now, and so don't have to run "a little rich" to fuel the afterburner, the milage still sucks?

    My "government intervention" detector suggests all those standards and requirements that have been building up over the decades have created a situation where they are trying to do more, and that costs fuel. The MTBE contradiction: It reduces emissions, but burns less efficiently so more fuel is burned thus increasing emissions.

    I would be interested to see a tiny rotary compared to a tiny turbine to be connected to the generator of a hybrid. I wonder how those two scale compared to pistons? Hmmm.....

    Bob-

    --
    The Ludwig von Mises Institute. The reasoning individuals economics
  9. Re:Bad link by lgw · · Score: 2, Interesting

    Sometimes it makes sense to have a seperate car for commuting, and a 200 mile range is fine for that. Sometimes people buy a sportscar just to have fun with, and a 200 mile range is fine for that.

    We won't see an electric car that's practical as an *only* car until someone invents the magic battery, but there are still viable niches. Of course, America simply doesn't have the electrical distribution infrastructure to replace more than a few percent of the gas we burn in cars without a multi-decade infrastructure build out, so electric car use couldn't grow rapidly in any case.

    --
    Socialism: a lie told by totalitarians and believed by fools.
  10. Reality: Some of us don't use coal or oil by WillAffleckUW · · Score: 2, Interesting

    I for one live in the Pacific Northwest, where more than 90 percent of our energy supply comes from renewable hydroelectric energy, and we also have massive wind farms too.

    I used to live in British Columbia, Canada, where - again - we used hydroelectric power.

    Some people live in the EU, where by 2012 more than 20 percent of all energy will come from renewable sources like wind power, biomass, solar, and so on. France, for one, gets most of its power from nuclear fission, which while having horrendous waste byproducts, is supposedly less polluting. Some places like Scotland and Norway use tidal power.

    Most of these don't add carbon to the atmosphere and in fact help calm down the overabundance of energy stored in our oceans that is one of the side effects of global warming (technically global massive temperature oscillation, as it can get really cold really fast just as much as really hot really fast, both locally and globally, when you start messing with the global weather patterns).

    So, just because when you drive an electric car it means you burnt coal, doesn't mean when I drive an electric car it burnt coal. In my case, it runs on snow turned into river water.

    --
    -- Tigger warning: This post may contain tiggers! --
  11. No, no, NO! by crhylove · · Score: 2, Interesting

    The obvious solution to the whole debate is to get a hold of the US flywheels we are currently using on the ISS. There's no reason we can't mass produce them and replace batteries with a more efficient electrical storage system. Other than of course a few patents, which is of course why I'm in the Pirate Party.

    The needs of humanity and the planet are more important than any patent.

    rhY

    --
    I hold very few opinions. I hold information based on observation and fact. If you wish to disagree, please use facts.
  12. There is plenty of load at high speed... by Shanep · · Score: 2, Interesting

    Also, I'm skeptical that you'll be getting 250 miles at 70 mph. If I remember right, electric motor efficiency and power typically increase with load, but fall off with speed, which makes them awesome for say, a 0-60 run in 3 seconds, but marginal at best for high speed cruising.

    The major loads involved here are due to weight and drag. Weight mostly hurts acceleration and drag mostly hurts top speed. To double your top speed, you must quadruple your power. That should be a clear indication that there is plenty of load near the top speed of a vehicle.

    --
    War crimes, torture, lies, illegal spying... Would someone give Bush a blowjob, already, so he can be impeached?
  13. The real solution.. by RobiOne · · Score: 2, Interesting

    For now, the Tesla sports car is a technology showcase, and an incremental bump in efficiency, or so they claim with their 250mile range and 3.5hr charge time.
    Someone mentioned why build it? Because it's suicide to build anything else first for the company.. it needs brand recognition and a cash infusion for their "cool, new" prototype, and guess what, people here in the silicon valley will buy it, because it's better than the TZero and can actually take you places and beat the 150mile range of the Civic GX for example (which runs on CNG). Don't get me started on CNG (compressed natural gas).. it's been around for ages, Europeans have been modding their cars with systems like Bedini and have dual gasoline/CNG. I had one myself.. which doubles your range.. I had something like 600-700miles on both tanks.
    Why isn't this bigger in the US? Ask your favorite car company and their politicians.

    Now for the real solution.. the only way we will get to transportation heaven is to cascade a multitude of technologies and efficient energy conversions in such a way that the efficiency for the leftover byproducts keeps the entire system conversion cycle running many times over.
    This is something along the lines of burning hydrogen which creates heat and water, where the heat is used, and the water is used again to make more hydrogen. Simple example with diminishing returns, but imagine a chain of conversion reactions 10-20 elements deep. Much better. Now put together high efficiency motors, channel all their heat output to a boiler for steam which spins a Tesla Turbine, and round and round we go.

    What about Klein/HHO/Brown Gas? Aka Aquygen. This gas, made from plain water exhibits amazing properties. Originally used by welders for cutting the hardest metals in seconds, this gas is cheap to produce and can be made so fast, that a car could run with a generator making the gas on demand.
    Combine that with electric and you have a car that runs on water. Perfect for Seattle with some built in rain collectors. Wanna fill up on a hot day? Get a carwash. Or find a deep enough puddle. Fuel stations could be as simple as large dips in a driveway filled with water you drive through. How's that for convenience.

    Single fuel/cycle technologies won't survive as none are effienient enough. Technology integrators who figure out the right sequence of the cascading fuel/energy conversions will make interstellar travel possible. The rest just need to fill in the gaps and work on efficient matter and energy conversion.

    Let's hope in our lifetime...

    --
    -- Robi