As much as Elon Musk loves to run his mouth (and boy, does he love to run his mouth), he is still, by his own admission, a few years from producing an affordable pure-battery EV. And then, the supercharger deployment rate would have to jump by an order of magnitude or so. Which means, aside from city cars and second cars, us regular folk (e. g., apartment/condo dwellers) are still living in an era of hybrids.
We are not even close to seeing what vehicle hybridization can do. Except for expander-cycle engines (the Atkinson/Miller operating cycles), today’s hybrids have regular piston engines, just a bit smaller. In hardware terms, the Atkinson/Miller Cycles only vary the cam profiles- you can barely see it. Many other means can make electrification interstate-ranged, less charger-reliant, and more flexible. As a field example, BMW’s 1.5L in their upcoming i8 is, by some metrics, their most advanced engine ever.
Why not jump directly to batteries alone? Sure, there’s something to be said for simplicity, and for a clean break when the opportunity presents itself. But there are reasons- some more plausible and pressing- why some form of consumable, “combustible” fluid still appeals, and won’t go away for a while:
-Emergency power and logistical redundancy
-Thermal power and conversion processes (or lack thereof)
-Mechanical transfer versus ‘the cloud’
-Daytime grid demand and infrastructure buildout
Oh, and by the way, I’m not hybridized, and am not a hypocrite. I am a special case where I sport a low charging current, I live close to work, close to groceries, close to an airport, trains, etc. So I, personally, only need a (physical) backup for my own peace of mind, as:
Emergency Power and Logistical Redundancy
On the most basic level, a plug-in hybrid covers the bases versus either full-gasser or full-BEV. A BEV never worries about gas lines and rationing; a gasser never worries about power outages. But a plug-in hybrid (of some sort) is all set, all the time. What’s peace of mind worth? And if you don’t think your power will ever go out, I have one word: Hackers. In case of a conflict, hackers from China, Iran, or wherever will make our critical infrastructure a day-one target. Not only does that include electrical transmission, but we have just found China had compromised the valves that operate natural-gas pipelines. And that’s just what we’ve found; security means wondering what we aren’t even finding.
Sure, a pure-BEV owner can buy a generator, and sock away a jerrycan for it. But that’s a pretty kludgy setup, for multiple reasons. Generators are typically inefficient, noisy, and polluting (sometimes all of the above), unless you spring for a really nice, really expensive one. If you have a nice, expensive generator, you are on the hook to maintain it, and use it too to some degree: a generator that’s just sitting there is still costing you money, in the economic sense.
Meanwhile, if you have a well-designed hybridization system, it will “maintain” itself via the engine computer, but with less wear than a 100% gasser. It will already have full noise and pollution controls. It will be a fully-integrated system from the factory, not a jerrycan kludge. And it also gains the benefits further below.
Not all hybrids are well-designed, of course. Since you are now carrying your “generator” along, in a factory-integrated system, there are different issues to be tackled. Weight and vibration are still present, but milder. The engine size and hybridization level has to be chosen to make sense, between the gasser starting and stopping too often, and not running enough to justify itself. And the engine interfaces (controls and a generator, transmission, or both) must be appropriate for the hybridization level.
Solar panels can back up an EV… can, not will. Most inverter-based (AC) systems need the grid for their frequency sync, and also go down in outages. In my case, I’ve carefully specified a system to be grid-independent (DC) and suitable for the pack in my EV. New solar installations are going AC-specific, and I hardly expect “regular” people to do the sort of systems engineering I did. (No, I will not disclose the details of my system. Security, you know.)
Of course, some households “hybridize” via… the other car. Many (most?) families own more than one; the fact that one uses electricity does not block the gasser (or non-plug-in hybrid). Ask a motorcyclist; in another life, I might have one pure-electric bike, and a gasser cage, and I’m covered. And my house also has lots of sweaters and insulation, in case of a conflict with China.
Thermal Power and Conversion Processes (or Lack Thereof)
One word: heater. Electricity is really good at producing torque through an electric motor; it’s not that good at producing heat, through resistors. Nissan stepped it up for 2013, using a heat pump in the MY’13 Leaf. Volvo prefers a little alcohol burner for the cabin. Ford, GM, Toyota, et al basically suck it up and hybridize.
The issue here is the energy conversion process. When possible, avoid converting energy from one form to another, since no process is 100% efficient. Really, the Second Law of Thermodynamics has not been directly broken in, oh, ever. There are processes that are over 90%, but this ain’t one of ’em. (Bare electric motors can be over 90% efficient, but after the battery, motor controllers, tires, etc. the net energy efficiency is in the 80s.)
In a resistor, the “heat” comes from being a poor conductor, impeding the flow of electrons. This is nowhere near 100% efficient, or the current would fall to zero and the system would defeat itself. Even then, that impediment to electrons must face more processes. The atoms of the resistor vibrate, in the intrinsic definition of heat. Those atoms must then vibrate other atoms, transferring heat out to the surface, across to the air via more vibrations, and through the moving air to you.
Contrast this with combustion: the exhaust gases were themselves the reactants (the air and fuel). The energy of combustion does not need to jump between atoms, because those atoms themselves came in and supplied the combustion energy. There is still at least one conduction process, of course. Direct gasoline exhaust (let alone diesel) would snuff the cabin. This is why Volvo uses alcohol, or propane, or similar: combustion gases like this, with low toxicity, can enter the cabin, skipping steps and maximizing delivered energy.
In this case, the “heat engine” wins. Burning a fuel requires lots of conversion processes to go from gas heat to wheel torque, which is why that’s inefficient. Keeping the energy as heat keeps conversion losses down, efficiency up.
In my case of course, motorcyclists suck it up. Either we bundle up, or hang it up for the winter.
Mechanical Transfer Versus ‘The Cloud’
Heat engines are refueled, electrical systems are connected to conductors. On the process level, refueling wins. It’s on the logistical level that electricity comes out ahead, since there are more conductors, more places, with multiple, independent ways to source its current. (If you’re reading this now, I’m going to say your home has electricity. I doubt you have your own gas station.)
Why does the process of refueling top the process of conduction? It’s about scale. The physical impediment to refueling- power transfer via transfer of some fluid- is mainly viscous drag, at least for the common fuels. Drag occurs whenever fluid at some speed encounters something else, at some other speed. In the case of refueling, ‘something else’ is the walls of the lines, pumps, connections, etc.
But a funny thing happens: only the outside of the fuel flow ‘knows’ about the walls. The fuel just inside from that fuel will only see other fuel molecules. So a fuel line has a ‘boundary layer’- a thickness of fluid, against the wall, that’s experiencing a speed differential, and thus drag. As you go inward from the wall, the speed differential falls rapidly, and the drag too. In the center of the fuel line, it’s full speed ahead.
(There’s more to it than that, of course. The exception is tiny fuel passages, with “tiny” dependent on the viscosity (“thickness”) of the fuel. However, given the viscosities of common fuels, the boundary layers are thin, and common fuel hoses are nowhere near the point where they’re considered tiny and drag-limited.)
Now, what’s in a conductor? Electrons flow through conductors, crystals of metal. Solid metal. Thousands of little crystals all smushed together. While electrons don’t feel the same concept of drag that flowing molecules do, conductors don’t have an “inside,” either. Electrons actually like the “outside,” and if you hollow out a wire you simply produce two draggy outsides. Electrical resistance does not respond to scaling effects that can make it fall nonlinearly and rapidly, and there’s no equivalent to a fire hose but in copper.
(Again, there’s more to that than that, of course. The exception is superconductors. But all known superconductors operate at brutally-cold temperatures, and will not be installed in homes or even most residential neighborhoods. It is physically possible for supercold stations to exist at highway stops… up to the point where completely untrained people walk up, grab the handle, and wave it around. Not cool.)
The redeeming quality of electrons is that the motors are many times more efficient, so you need fewer of them. (Motorcycles even less, of course.) The household outlet thus works surprisingly well, for a surprising amount of people, a surprising amount of days. But not all- hence, plug-in hybrids: use common outlets for commuting and errands, but a low-drag hose for the occasional bad day or road trip.
Daytime Grid Demand and Infrastructure Buildout
Those common outlets and fuel hoses are already built and installed. Today. As you read this. Wherever. There is no need for future developments and rollouts- the future is here (so long as you stick to installed receptacles and gasoline/diesel). In other words, moderate amounts of electricity for short trips, liquids for long ones- i. e., a plug-in hybrid. One analysis had specifically recommended plug-in hybrids. The cost of installing a network of public infrastructure, they claim, didn’t appear to be worth the gas savings, given how many people only drive a few miles in their typical day. At typical, low miles per day, drivers can and should use a simple home outlet.
Of course, there is more than one common outlet- ask me how I know. Most single-family homes, and even the larger apartment units, have some sort of dryer outlet or range outlet, and possibly in or near the garage already. There is no need to stick to the NEMA 5-15R specifically. Hence, the pack capacity and all-electric range required to hold off an infrastructure network deployment is variable, for various people, with various installed in their home.
Of course of course, there is more than that at issue here. GFCI aside, the existing outlets weren’t designed for rain, sleet, salt, toddlers with sharp objects, teens with blunt objects… and simply being plugged and unplugged day in, day out. The SAE J1772 standard, though, was designed for public vehicle infrastructure. It, or something like it, was probably going to happen anyway. And if you’re going to install a new, hardcore connector, then you might as well go to higher powers than NEMA 5-15 or even dryer plugs will deliver. The typical public J1772 units will give as much juice as wiring, already built and installed today, will put out. (The standard will go all the way up to 80 amps- way higher power than 30A dryer plugs, though I’m only seeing 75A units so far.)
Of course of course of course, there’s more than that cost that has a cost. Besides the physical cost of infrastructure deployment, there’s some contention on the grid (the BIG infrastructure). Electricity for charging is widely available at night; power plants may actually be getting rid of excess electric power. But availability is less in the afternoon- and much less available on hot summer afternoons. Then, air conditioners are drawing all the grid has, tautologically: utilities plan their max capacities based on what A/C load they anticipate for a hot day.
Nighttime EV charging is thus neutral (or actively beneficial), while afternoon charging is undesirable, and charging on hot afternoons is actively bad. Some analyses then favor plug-in hybrids not only because they stick to existing sockets at night, but existing generating capacity. If a hot afternoon is straining the grid, you can burn a little gas and avoid being the last straw.
Is this a credible analysis result? Maybe, maybe not. Not all PHEV drivers know or care about grid strain in general, let alone during any particular hour. And a few years’ experience now shows that PHEV drivers try to plug in wherever and whenever they can, day, night, or whatever, since electricity is cheaper than gas. After all, that’s the point of buying a PHEV.
On top of that (literally), some charging sites (public and private) feature solar arrays. Tesla in particular brags about installing arrays at their Supercharging sites, though at this moment only a few have them. They are hardly alone in this. If the majority of the power is from the arrays, then not only can you charge during summer afternoons, you’re pretty much compelled to.
* * *
Hacker, heater, charger, charger. I thus see hybrids (in at least some implementation, TBD) hanging on for years and years. Some of the above lines of reasoning are better than others, but all contribute to marketing and psychological roadblocks to mass adoption of 100% BEVs. Maybe the greatest reason for an onboard generator (in some form) is the psychological breakthrough.