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posted by Fnord666 on Friday July 07 2017, @06:16PM   Printer-friendly
from the I-have-methane dept.

http://www.bbc.com/news/world-europe-40518293

France is set to ban the sale of any car that uses petrol or diesel fuel by 2040, in what the ecology minister called a "revolution".

Nicolas Hulot announced the planned ban on fossil fuel vehicles as part of a renewed commitment to the Paris climate deal.

He said France planned to become carbon neutral by 2050.

Hybrid cars make up about 3.5% of the French market, with pure electric vehicles accounting for just 1.2%.

It is not yet clear what will happen to existing fossil fuel vehicles still in use in 2040.


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  • (Score: 1) by khallow on Saturday July 08 2017, @04:12AM (9 children)

    by khallow (3766) Subscriber Badge on Saturday July 08 2017, @04:12AM (#536409) Journal

    The range issues will be completely fixed in 20 years.

    I'm betting against that. The key problem is simply that batteries are less efficient chemical storage than gas tanks. Gas tanks don't need to store all of the reactants - air provides the oxidizer - nor do they need to store the resulting reaction products - those go out the exhaust pipe. This causes two related effects from the higher energy density, longer range and lighter vehicles. I think it'll be easier to come up with a more efficient combustion engine (such as a turbine electrically coupled to electric motors at the wheels, hybrid-style) than to come up with a safe enough battery technology with higher energy density than gasoline.

    Now, if they can come up with a viable battery technology based on nuclear physics (say some sort of tritium-based battery with a far higher energy density than any chemical or mechanical storage system can achieve), then the game changes and electric vehicles would indeed be far more viable. I just don't see that happening in the 20 year time frame.

  • (Score: 3, Informative) by Grishnakh on Saturday July 08 2017, @04:53AM (8 children)

    by Grishnakh (2831) on Saturday July 08 2017, @04:53AM (#536425)

    Batteries don't need to store as much energy as gasoline. With combustion, you waste most of the energy in the form of heat, and immediately are stuck with, at the very best, about 45% efficiency, which is practically unachievable in a car, where it's really more like 35% best-case. Batteries have efficiencies in the 80-90% range, and electric motors are in the high 90s. Turbines aren't more efficient, they're actually horribly inefficient internal combustion engines. They only use them in aircraft because the power-to-weight ratio is so much more important there, and because they can scale them way up. There's a reason that small airplanes and even helicopters still use piston engines.

    Teslas are already achieving about 250 miles of range or better per charge. That's not that much less than a gas-powered car; my compact gets about 400 miles if I only drive on the highway, and in the 300s otherwise. So batteries only need to get maybe 30% better to be comparable to gas cars, or people can just revise their range expectations. The problem with EVs now isn't range, it's battery cost, and recharge time/difficulty. Battery cost is keeping the 200+ mile range only accessible to higher-income customers, and recharge issues make the cars problematic for anyone wanting to drive more in one day than their battery capacity allows. Fix those two problems and gasoline will be obsolete.

    • (Score: 1) by khallow on Saturday July 08 2017, @06:14AM (4 children)

      by khallow (3766) Subscriber Badge on Saturday July 08 2017, @06:14AM (#536444) Journal

      With combustion, you waste most of the energy in the form of heat, and immediately are stuck with, at the very best, about 45% efficiency

      True, yet not true. You can do better than 45%, but it requires a different sort of engine than the piston/rotary engine.

      Batteries have efficiencies in the 80-90% range

      No they don't because you need to charge them as well. Fast charging in particular has high losses. And the electricity power source isn't going to be 100% efficient either though that usually gets ignored since what matters is the cost of the power at the point that it enters the vehicle.

      Turbines aren't more efficient, they're actually horribly inefficient internal combustion engines.

      But they can be used in combination with other engines to generate much higher efficiency than 45%. For example, from Wikipedia:

      An open circuit gas turbine cycle has a compressor, a combustor and a turbine. For gas turbines the amount of metal that must withstand the high temperatures and pressures is small, and lower quantities of expensive materials can be used. In this type of cycle, the input temperature to the turbine (the firing temperature), is relatively high (900 to 1,400 °C). The output temperature of the flue gas is also high (450 to 650 °C). This is therefore high enough to provide heat for a second cycle which uses steam as the working fluid (a Rankine cycle).

      In a combined cycle power plant, the heat of the gas turbine's exhaust is used to generate steam by passing it through a heat recovery steam generator (HRSG) with a live steam temperature between 420 and 580 °C. The condenser of the Rankine cycle is usually cooled by water from a lake, river, sea or cooling towers. This temperature can be as low as 15 °C.

      That yields a theoretic maximum (for 1400 C heat source dumping to 15 C heat sink) of over 80% (I understand that the real world thermodynamic efficiency of these combined engines is around 60-70%). Even if you end up with the weaker situation of 1400 C dumping to 80 C (for a car, that would be much more typical), that would be 1673 K dumping to 353 K which would cap out at a theoretical maximum of around 79%. My point here is that you can get far higher temperature differentials between hot and cold sinks by using a turbine engine combined with something else than an cylinder or rotary-based internal combustion engine by itself. And we see that in play in actual natural gas generation today. Obviously, using such an engine in a car is going to be harder and more complex than current automotive engines of any sort, but that, combined with the lighter mass of the overall system, including energy storage, makes the engine competitive with the most efficient of electric engines and storage systems.

      I think in addition that the actual hot sink temperature can be made hotter than 1400 C though it is probably not practical for the foreseeable future. For example, rocket engines can run with temperatures as high as 3500 K (~3200 C) with kerosene or hydrogen. At that point, you could get thermal efficiencies of almost 90% even if you were to dump the heat at the boiling point of water (for an air-cooled engine you should be able to do better than that). But that would likely have to include a device for greatly concentrating and pressurizing oxygen before running the oxidizer through the engine and possibly a three-stage combined engine with extreme material demands (say liquid-cooled rocket -> turbine -> Rankine cycle, for example) which overall would result in a very complicated engine.

      The point here is that we aren't tapping the full efficiency of gasoline-powered (and similar hydrocarbon-fueled) engines. So it doesn't make sense to discontinue a good idea and reduce the performance of our vehicles merely because some part of society has a hard on for electric vehicles and hopes that the technological difficulties of the electric vehicle can be figured out in the next two decades.

      • (Score: 2) by Grishnakh on Saturday July 08 2017, @07:09PM (3 children)

        by Grishnakh (2831) on Saturday July 08 2017, @07:09PM (#536609)

        You can't do combined cycle power plants in a car. There isn't enough room in there, and the power-to-weight ratio is still important unlike a ground power plant. Also, notice your bit about cooling from water from a lake or river: you can't do that in a car for obvious reasons. So this comparison is totally invalid. There's no convenient working fluid around a car for it to dump heat into: you can't count on air to be moving (it only does that when you're at speed), and that air is liable to be 120F or hotter. It's very simple: if this crazy plan made any sense, someone would have tried it already.

        You can't run car engines as hot as rocket engines. Rocket engines use advanced materials like beryllium to do that stuff, and rocket engines cost an absolute fortune, plus they're not all that reliable compared to car engines. You can't make a car engine that can handle such temperatures at an economical price. Batteries and electric motors don't have these problems.

        We *are* tapping the full efficiency of gasoline-powered engines. There just isn't much potential left in them. The best you're going to get is the newest ideas of running gas engines like diesel engines, using compression ignition, but that's very problematic too because fuel quality varies a lot, which again is something that's not such a problem with large-scale power plants.

        because some part of society has a hard on for electric vehicles

        This bit is just plain stupid. Hydrocarbon vehicles create enormous amounts of pollution, and worse, they do it in populated areas where people have to breathe it. These engines are frequently not well maintained, and emit more pollution as they age. They're also causing global warming, whether you choose to believe it or not, which is going to have drastic effects on society. Moving to a more efficient solution isn't just some people "having a hard on", it's the only rational move, unless you're some kind of religious idiot.

        • (Score: 1) by khallow on Saturday July 08 2017, @10:11PM (2 children)

          by khallow (3766) Subscriber Badge on Saturday July 08 2017, @10:11PM (#536661) Journal
          I strongly disagree on your claim. It just hasn't been worth our while yet to build a more efficient hydrocarbon-based engine. In part, because it's not easy and in part because the economics of fossil fuels just haven't justified an engine that efficient.

          Hydrocarbon vehicles create enormous amounts of pollution, and worse, they do it in populated areas where people have to breathe it.

          True, yet not true. Hydrocarbon vehicles create enormous amounts of pollution, but they don't need to. A regulatory policy which eliminates the worst polluters would substantially drop the pollution from vehicles in the developed world.

          They're also causing global warming, whether you choose to believe it or not, which is going to have drastic effects on society.

          Unless, of course, it doesn't have drastic effects on society. It is worth noting here that advocates for global warming mitigation have had an extraordinary difficult time to actually find negative effects of global warming that significantly affect society and occur on a time frame where we can verify the affects in our lifetimes.

          • (Score: 2) by Grishnakh on Monday July 10 2017, @03:15PM (1 child)

            by Grishnakh (2831) on Monday July 10 2017, @03:15PM (#537134)

            I strongly disagree on your claim. It just hasn't been worth our while yet to build a more efficient hydrocarbon-based engine. In part, because it's not easy and in part because the economics of fossil fuels just haven't justified an engine that efficient.

            Well, apparently, is HAS been worth our while to build both EVs and hybrids (both serial and parallel), because we have a shit-ton of them out there now.

            True, yet not true. Hydrocarbon vehicles create enormous amounts of pollution, but they don't need to. A regulatory policy which eliminates the worst polluters would substantially drop the pollution from vehicles in the developed world.

            Prove it. Let me see your zero-pollution hydrocarbon engine that costs on the order of a current EV drivetrain. Put up or shut up. I'm really sick of your idiotic claims that have no basis in reality.

            • (Score: 1) by khallow on Tuesday July 11 2017, @12:03AM

              by khallow (3766) Subscriber Badge on Tuesday July 11 2017, @12:03AM (#537383) Journal

              Well, apparently, is HAS been worth our while to build both EVs and hybrids (both serial and parallel), because we have a shit-ton of them out there now.

              But not because of economics. Status signalling is a common human activity and EVs and hybrids play to that desire.

              Prove it. Let me see your zero-pollution hydrocarbon engine that costs on the order of a current EV drivetrain. Put up or shut up. I'm really sick of your idiotic claims that have no basis in reality.

              I'd say that most modern cars achieve that well enough, such as the already mentioned Nissan Tiida/Versa. Further, if we use renewable fuels such as biofuels, then we don't even have a global warming contribution.

    • (Score: 1) by khallow on Saturday July 08 2017, @06:23AM (2 children)

      by khallow (3766) Subscriber Badge on Saturday July 08 2017, @06:23AM (#536449) Journal

      Teslas are already achieving about 250 miles of range or better per charge. That's not that much less than a gas-powered car; my compact gets about 400 miles if I only drive on the highway, and in the 300s otherwise.

      Let us note that if we were to devote a similar portion of the mass of the compact car to gasoline storage as is used for electricity storage on a Tesla, we would have a range of several thousand miles (an 85 kWh battery with the 250 mile range weighs over 500 kg - that's a lot of gasoline).

      • (Score: 2) by Grishnakh on Saturday July 08 2017, @07:01PM (1 child)

        by Grishnakh (2831) on Saturday July 08 2017, @07:01PM (#536608)

        That's a bad comparison. The gasoline engine in a gas car also has a huge mass on that same order, and EVs don't have such things, only electric motors which are much smaller and lighter. A Tesla isn't significantly heavier than a similar luxury car in that class.

        • (Score: 1) by khallow on Saturday July 08 2017, @10:21PM

          by khallow (3766) Subscriber Badge on Saturday July 08 2017, @10:21PM (#536664) Journal

          The gasoline engine in a gas car also has a huge mass on that same order, and EVs don't have such things, only electric motors which are much smaller and lighter.

          Try comparing vehicles of the same frame and design. For example, the Nissan Leaf [wikipedia.org] is based on the gasoline-powered Nissan Tiida/Versa [wikipedia.org]. The curb weight of the former is 1500 kg while the weight of the latter is 1100 kg. That's almost a 40% increase in weight of the electric vehicle despite Nissan going to great lengths to reduce the weight of the vehicle. You will find that the mass of the electric storage system is heavier than the mass of the added components of a gasoline-powered vehicle.