If I recall correctly, the press has been calling the Chevy Volt a plug-in hybrid for years. I've been following the progress have have never known it as anything else. Yet the article cited says:
"That means that for all of the all-electric or extended-range electric vehicle (EREV) hype GM's imbuing in the Volt, it's really nothing more than a plug-in hybrid vehicle. A very advanced plug-in hybrid, but a hybrid nonetheless."
The article comes off as a large quantity of smugness - essentially insisting that use of a specific technology is more important than developing the best possible vehicle. Maybe GM management really wanted an all electric car that just used the gas engine for feeding the batteries, but the engineers found that use of the gas power plant to augment the electric at high speeds (where the gas engine is efficient) makes more sense than adding in the extra current capacity that would allow the electric to power the car solo at high speeds.
If that's the case, I'd rather take the engineering solution than the "marketing solution" that I'm supposing management wanted.
The biggest potential of a combo gas/electric drive vehicle is not that it's "all electric", but rather that each power plant can be used in the power band where it is the most efficient. Further, in some circumstances, both can be used simultaneously, allowing for smaller versions of each.
Using the electric for high horsepower acceleration, which is a short duration event, requires a certain amount of copper and silicon. Using the same amount of electric horsepower for sustained high-speed use would likely require significantly more copper and silicon. Why do that when you have a nice gas engine that would be running anyway to charge the battery, but is nice and efficient for the sustained high-speed driving?
Now the "230 mpg" hype seems to me to be just that - hype. And that, really does bug me.
At highway speeds, you have put tens of kW into the wheels. I'd rather have moderately sized electric drive, helped out by gas when real power is needed. Besides, I wouldn't want to resort to Flintstone mode when the batteries die.
Its only been about 15 years since i ran the numbers, but i think your starting point is incorrect. At HW speeds (say 70 MPH) wheel and air resistance costs about 5 HP. That is 3.5 KW, not tens. Where 10s of KW are needed is for acceleration, not for high speed.
If you look at the amount of carbon that electricity generation puts into the environment and work out what all of the energy inefficiencies are between the power plant and the drive wheel, and the amount of extra carbon goes into the manufacture of electric vehicles, you very quickly realise that a small diesel outperforms most electric concepts every step of the way. Also imagine what sort of power generation you need to charge more than 250 million cars overnight. At the moment California has blackouts trying to run a few air conditioners over night.
Personally I think the solution is to build reasonably efficient ICE's (internal combustion engines) and have the sunny places on the globe invest in solar plants that do nothing else but crack CO2 into C & O2. C can be buried or burned for base load and sold to countries that don't have much sun for the same purpose. Anybody that generates CO2 pays a tax that goes the the CO2 crackers to fund installation & maintenance. This technology does exist already, it just hasn't been used on a scale suitable for this application.
I know this is a little off topic in regard to the Chevi Volt, but what I want to point out is that electric cars are really a dead end compounding the GW problem, not a solution for what it's really about, which is reducing carbon footprint.
@Etmax, do we have any industrial solutions that crack CO2 better than rain-forests or sea-borne algae? Might be easier to organise your solution than you think.
The basic conflict is long term thinking vs short-term product marketing. Politics has both those influences conflicting internally, needs to balance them. People need to reassure government that we want longterm solutions.
@sharps_eng, In answer to the question on rainforests, they do a good job but generate methane and a whole range of other by products. Also the land The is home to lots of wild life so you don't want to cut down the trees to make room for more. The algae is better, but the algae equation is something like N+CO2+H2O+Fertiliser = algae, where industrial process I red about (have to find it again) had the advantage that the infertile strips that harbour few 'whales' (:-)) could be used and the equation is CO2+energy = C + O2. It needs a lot of energy, but then during the day there is a lot of sun. It uses a catalyst of some description, I only can't remember what it was.
Chevrolet Volt an EV? Aren't there too many pistons for an EV? Oh, I see, it's not an "engine", it's a "range extender".
Volt is a plug-in hybrid, and has always been that. Let's see how it performs, from well to wheel, in the real world. That's the only thing that counts.
I am interested to know about this CO2 cracker technology. If this can be done economically countries like India can be benefited, where there is a plenty of sunshine for 8 out of 12 months in a year, and a lot of CO2 generated in urban areas.
Any resources on the net?
For those interested in CO2 cracking, I found this on CO2 to CO + O which is not the one I remember but is also a useful method:
This discusses a patent for CO2 to C+O2
Seems to me that it's just sour grapes from those who don't like GM and will do/say anything to discredit them. I don't know why, but they like prius and don't like volt. Both are just innovations along a development path.
I need more daily range myself, but the volt it seems like a great idea. Overall it's a car that can run fully electric for most people on all of their small trips and still be used as a regular travel car for trips. At present, I don't see any other viable options for long distance electric. I think this is what the car is supposed to be, and it does that. So what's all the grumbling about?
I think you all miss the point. Is the public going to buy it? At $40K, if that is the price, it is pricey. I predict it will have modest success, but it will take time for GM to get the price and acceptance so the public will buy in to it.
But it's not $40K. It's like $32K after the government rebate. That's right in the middle of new car price ranges. What is the target market? Based on price, I don't think the prius target was the "public" either. I heard Toyota lost money on every one it sold and I think it was still pricey. The polls I've seen indicate people didn't buy it because of price.
Now, full general public acceptance is another thing. I wouldn't put any hybrid in this category yet. They're more of a "feel good" item after doing a fuel savings vs. cost analysis.
This design is a SERIES Hybrid, NOT a parallel one like the Prius and what was indicated in this article. There is no mechanical drive connection from gas engine to the wheels.
The electric motor is capable of full power freeway speeds, no limp mode needed. When the battery pack is discharged to a certain level, the gas engine (with another electric motor directly connected and running in regen mode) starts up and creates enough electric power to continue driving at same performance level.
This way, someone that commutes less than 40miles/day would normally never need/use any gas. Thus, it is a pure electric vehicle up to 40 miles. It then becomes a gas driven system, smoothly transitioning with little indication. But the electric drive motor is still the only source of power to the wheels.
This design was not chosen for political reasons! It was designed this way to eliminate the "range anxiety" of the typical American driver.
@Bob.Simpson: maybe you missed the latest statements from GM. They declared plain and simple that sometimes (i.e. beyond 70 mph *and* with depleted battery) the ICE is linked *directly* to the wheels. However, it is *never* the only torque source: in this case, both motors are running too.
Citing from http://gm-volt.com/2010/10/11/motor-trend-explains-the-volts-powertrain/:
"However of particular interest, when going above 70 mph in charge sustaining mode, and the generator gets coupled to the drivetrain, the gas engine participates in the motive force. GM says the engine never drives the wheels all by itself, but will participate in this particular situation in the name of efficiency, which is improved by 10 to 15 percent."
That's all the buzz about it. As I said earlier, who cares? It was obvious from the beginning that it had an engine on board. Does it change if the energy flows through one path instead of another? Let's see the results, that's the only thing that counts.
(PS I'm more worried for the weight: 1400 kg for the Prius, nearly 1800 for the Volt.)
I have to agree with Rich Krajewski. Government mandates are frequently poorly thought out. The requirment to increase fuel efficiency in our automotive fleets is a primary example. One way to meet these requirements is to skim weight from a vehicle in areas that would normally protect people inside from an accident. The result: An increase in injuries, severity of injuries, and fatalities (this has been documented) in 'bantam weight' cars vs. cars with lower fuel efficiency ratings.
Too bad law makers are subject to the overview of 'systems' people who look at the big picture and determine how a change in one area affects others. The results would be much more logical laws.
Slightly off the Chevy Volt topic, another badly thought out government regulation is lead free soldering in electronics. I actually increases land fill and dramatically increases CO2 emissions due to higher soldering temperatures. As you say, no system thinking.
If I understand correctly - the VOLT normally runs as a series hybrid (or pure EV) then has a parallel hybrid mode for higher power, by physically engaging / disengaging a clutch between the engine and wheels. The Prius is a full-time parallel hybrid. This "flap" is just a big pile of "who cares?", probably drummed-up by the VOLT marketing folks to get attention (like Paris Hilton who seems to think bad publicity is better than no publicity). The only real difference is that during EV mode, the geartrain is still engaged with the Prius, but the VOLT disengages it. Probably the *real reason* the VOLT does this (vs. the simpler Prius solution) is because Toyota has a patent on their parallel hybrid geartrain, and GM doesn't want to pay royalties, so GM "invented" a clunky way of getting around the patent. Technically - the GM approach is neutral-to-slightly negative.
By the way - the CO2 solar cracking catalyst is iron oxide...and has great potential. See: www.greencarcongress.com/2007/12/sandia-applying.html
Lastly - EV's do NOTHING to reduce CO2 emissions or fossil fuel usage (today). It just shifts the fuel from oil to coal+natural gas (at the power plant), and uses just as much total energy (if not more). Until we power our grid with renewable sources - EV's are a huge, wasteful distraction.
Solar PV, Wind, Biofuel, Solar Thermal grid power should be our technology development priority (perhaps along with CO2 splitting / sequestering) ...and the Biofuel (algae and cellulistic based, not corn) can be used for grid power as well as powering vehicles directly.
I checked the difference between the VOLT and Toyota hybrid transmissions...and it confirmed my suspicions. Toyotas "synergy" drive connect 2 electric motors and the gas engine to the wheels without mechancial clutches (except for normal gear-changes). They do "mode changes" electronically by how the electric motors are energized. The VOLT's clutches do the same thing...with higher complexity. GM must be doing "patent avoidance".
Re being "mistaken" about using EV's+Power Plants vs. ICE cars - no, I don't think I'm mistaken, I'm pretty informed. The facts are surprising, but are counter to most of the hype we hear from the government, car companies, even well-intentioned green folks. Don't get me wrong - I'm 100% in favor of changing our power grid to renewables ASAP. My point is that if you look at fuel-to-wheel (with TODAY'S grid) you'll see that pure EV's make no sense, don't reduce CO2 or energy usage. It's the coal and lithium lobbies, the govt (and misinformed green consortiums) that are pushing for EV's before their time. I'm not saying EV's are BAD, I'm saying that they don't do much good today, and are a distraction from the more pressing need to green the power grid.
However, EV's CAN make sense once most of the grid is green. HYBRIDS do have efficiency advantages today in some usage profiles due to regenerative braking and optimizing ICE efficiency...so that is a different conversation than pure EV's.
Lastly, we need to start doing more forward-thinking on how to convert the grid to renewables. PV's and Wind are OK for now...but can't be the MAIN power sources without energy storage for 365/24/7 power. Therefore, energy storage on a mass scale is needed. I think this is best done by solar thermal power plants, and biofuels (algae based being my favorite). Electric batteries (in battery farms or in vehicles) are too expensive and limited cycle-life to function as the grid's energy storage medium...at least today's battery technology.
The biggest question is does it work? And does it avoid a great deal of inconvenience for the driver? Since it has a gas engine and an electric engine, it is a hybrid, period... The government categories should be based on effectiveness. If a gas or diesel engine gets 60mpg, it should recieve more tax benefits than a hybrid that gets 20mpg. That gets rid of all the silly positioning...
I did a few checks on Google and most of the results pointed to Wikipedia:
A coal plant is ~33% efficient
A gas plant is ~50% efficient
Transmission losses are 6.5%
A diesel ICE is 50% (2 cylinder Large)
A Gasoline ICE is 43% efficient
freight losses for fuel? but a lot less than 6%.
An electric brush-less motor is 90% efficient
An electric brush motor is 80% efficient
Battery storage is ~90% efficient
Both of these are taken at full speed, ie partial load speed control losses not included, but I would 10-15% wouldn't be unreasonable.
This suggests to me that if you look at CO2 emissions over the life of the vehicle a small diesel may just be the best (current) solution due to the lowest effort to produce and one of the highest efficiencies.
@Etmax: one important point that IMO you are missing is the *mean* efficiency of an ICE during *all* possible load conditions. I agree with you that a properly sized diesel engine can be the best solution for highway cruising but no matter how efficient, it will still waste energy while braking, idling or when simply throttled down. Here comes the great efficiency of electrical motors, which are reversible and have good efficiency on a wide range of load-speed combinations (way higher/wider than an ICE). So, for urban driving, EV (and hybrids) have big advantages. I still think that the best solution will be a hybrid with a good ICE. BTW, I think the weak point of the Chevy Volt is the ICE: four cylinders are too many for such a small power output: a new design is needed, something like one or two cylinders, with staged and intercooled compression and turbocompound or miller/atkinson recovery, everything calibrated for a narrow working band.
To some extent hat is an issue, but Regenerative braking is more beneficial to saving brake pads than restoring power as batteries dump energy a lot better than they accept it. Because of this the CSIRO has worked on capacitor/battery combos but until they have a commercial example I will sit on the fence. What I do know is that small diesel non-hybrids currently have better economy than hybrids (perhaps due to weight advantages) and because they are a lot less carbon intensive to make may well be better (for the moment) for the environment. Diesels have good low end torque, not as good as electric motors, but over all performance is comparable. This link http://rac.com.au/About-Us/RAC-eNews/March-2010/Top-20-most-fuel-efficient-cars.aspx shows the top 20 cars tested and the Ford Fiesta is better (No 1) than the Prius (No. 2). I believe the VW Polo is also better. though not listed. There are 3 other Diesels that are on par with the Prius, and given the cost and lifetime CO2 difference they make the diesels environmentally friendlier.
To compare a Fiesta with a Prius is not fair. A Prius has almost twice the boot and has better seating. On the Italian market, I read as follows:
VW Polo 1.2 TDI avg. 3.3 l/100 km, 87 g/km CO2, 0-100 km/h 13,9 s, wheelbase 247 cm, 16 k€
Toyota Prius avg. 3.8 l/100 km, 89 g/km CO2, 0-100 km/h 10,4 s, wheelbase 270 cm, 26 k€
A good comparison will be done with the Auris Hybrid, which has a direct concurrent model, the Auris diesel. That will be interesting.
About the fact that batteries dump energy, your statement would imply that batteries heat up like brakes do, but that is not the case. Try driving a hybrid (even a mild one, like the Insight) and you'll see how the charge indicator jumps when braking gently (with empty batteries).
Thank you for your insight, it will be indeed be interesting to see the Auris to Auris comparison. I hope they give the cradle to grave CO2 figures too. It will be interesting. FYI, I don't disagree that regenerative braking works and is a significant aspect of electric vehicles hybrid or otherwise, only that it is not as efficient as one would hope. :-(
Etmax - thanks for the update with eff.numbers. It basically validates what I was saying...but a few numbers may be misleading. Here are my tweaks.
*A coal plant is ~33% efficient* yes.
*A gas plant is ~50% efficient* yes - but most are less.(60% is the newest high-tech GE natural-gas fired plant, not deployed in great qty yet.)
*Transmission losses are 6.5%* yes. or more.
*A diesel ICE is 50%(2 cylinder Large)* Only HUGE ship engines reach this level.
Advanced auto diesels (VW / Audi TDI) are up to about 40% thermal eff.
*A Gasoline ICE is 43% efficient* A bit optimistic, usually low 30's%, mid 30's% for advanced ICE like the Prius Atkinson engine. Old V-8's were mid-20's% efficient.
*An electric brush-less motor is 90% efficient. An electric brush motor is 80% efficient.* yes
*Battery storage is ~90% efficient* Less when considering full charge / discharge cycle.
Regenerative braking helps city cycle efficiency a lot, but doesn't help highway cruising at all. It all depends on driving cycle.
Net-Net, pure electric vehicles do NOT save energy, do NOT reduce CO2, have serious practical problems and cost a mint. Hybrids solve most practical problems, but also have high cost.
Once a high percentage of the grid is powered by renewables - THEN (and only then) will EV's make sense. For those that don't care about the cost - hybrids (or plug-in hybrids) are an OK mid-term solution.
"Once a high percentage of the grid is powered by renewables - THEN (and only then) will EV's make sense. For those that don't care about the cost - hybrids (or plug-in hybrids) are an OK mid-term solution."
Totally agree on that. I'll add: if one really needs an energy intensive vehicle (SUV or van) and/or plans to drive mostly on highway, he/she should go for a diesel. In the meanwhile, let's study how to reduce energy waste of homes (thermal end electrical).
It's going to be very difficult to compare electric to gas or hybrid but comparing gas to hybrid is simple since the same fuel is dumped into the tank. In the case of the civic, you can also throw in CNV. the Fueleconomy.gov site can give practical info. After almost 150K on my Civic hybrid (originally purchased only for the car pool sticker), I've used about 3300 gallons of gas, versus 6600 for my 23mpg caddy I was driving or 5000 gallons for my 30mpg ford focus (these are my actual commute mileages, not the EPA estimates). A "normal" civic would have used the same as the focus (also a 30mpg combined). The CNG version gets 26mpg of CNG. So whether it's the Atkinson engine, the regen braking, or whatever, it amounts to a very signficant gas savings. I expect the Volt to have similar overall savings. As far as cradle to grave, time will tell..
`(Somewhere above here it was said that it takes 5 HP to run at 70mph?) I believe one experiment is worth a 1000 expert opinions. Remember mechanics in physics? A reasonable approx is Energy/time = ((1/2)(mass_of_car)(70mph^2) - (1/2)(mass_of_car)(60pph^2))/time Measure the time.....I got about 22HP for my station wagon. (If U assume the drag is directly proportional to velocity and not the square of velocity, you can come up with an exponential curve as a function of speed.)
BMW did a study into what type of driving saves the most fuel. They tried 1. accelerate rapidly to the desired speed and maintain. 2. accelerate beyond the desired speed and coast back down to it. 3. Drive like a granny (my apologies to all the grannies out there) ie. accelerate slowly to the desired speed. They found that No. 1 on average offered the best fuel consumption. This was of course for a conventional ICE. This makes a lot of sense when you think about it. It would be interesting to see this done for pure EV's and Hybrids to see whether there are differences
Etmax - yes this make perfect sense (within limits)! Higher speed definitely uses more fuel. However, at low loads ICE's waste a lot of energy via pumping losses across the throttle plate (efficiency plummets). The most efficient throttle setting is usually about 3/4 open throttle - where these losses are minimized, but "power enrichment" fuel mode has not started to add more fuel. So... moderate accel + constant speed would seem to be optimum. In fact, most ICE "Eco-Marathon" competition vehicles have no throttle, and just accelerate / coastdown repeatedly. ICE's don't throttle-down efficiently (but diesels are much better in this regard !) see: http://en.wikipedia.org/wiki/Eco-marathon
For more detailed data and discussions on related topics - try checking out the blog of the 100 MPG automotive X-Prize winner (Edison2). This car used an ICE (burning E85) and beat all the electric vehicles in its class (even though the rules actually favored EV's): www.edison2.com/blog
It's fine and dandy to be satisfied that the Chevy Volt "works," but I would think that engineers ought to be curious, and ask "how"?
Did you guys listen to this?
The GM powertrain engineer uses a bit of techno-babble, if you ask me, saying that the engine must always "react against" an electric motor. Whatever that means. But what it comes down to, wading through the fog bank, seems to be this: The two electric motors have their outputs combined by a planetary gear arrangement, to reach the wheels. The internal combustion engine ALSO feeds this planetary gear arrangement directly, i.e. mechanically. However, the electric motors must remain engaged even when mechanical power from the engine is mechanically feeding that planetary gear arrangement. (E.g., is one of the motors acting as a generator at this time? Probably that's all "react against" means.)
To me, sorry Chevy, this makes the car a plug-in hybrid. Not saying this is bad, not saying the design tradeoff was not well thought out, just saying it ain't a pure electric car. Notice how the engineer defines it as an electric car, more than once, only by mentioning the first 40 miles of driving.
At relatively how output, internal combustion engines become most efficient. So okay, that's why they did it this way. I'm hoping for fuel cells to become feasible soon.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.