An Electric Very Light Car?
Saturday, August 7, 2010 at 10:59AMEdison2’s Very Light Car Scoffs at Electric Avenue said AutoBlog Green in January, highlighting the irony of our internal combustion engine powered car sitting in the midst of all the electrics at the Detroit Auto Show.
But electric vehicles are here to stay and an electric VLC makes sense. Our breakthroughs in platform efficiency make all vehicles way more efficient, regardless of power source, and in an electric help solve issues of cost and range.
Billions are being invested in electric vehicle technology for a number of reasons. EV’s provide a path to energy independence and with American jobs, whether in the creation of green energy sources or in the mining and processing of coal. As a new industry, electric cars have the potential to revitalize important sectors of our economy. Electric vehicles are particularly efficient in short-cycle applications, such as Postal Service vans or some predictable commuters, and the relocation of emissions to a distance can be an advantage. Night-time charging will utilize excess generating capacity, and as the electric grid becomes green so can the future of transportation.
Currently, however, electrics cars have real issues. Batteries are heavy, big and costly. With electric drives cars get heavier, performance suffers and costs go up. Range is especially an issue, as witnessed by the numerous EVs in the 100-mile range X Prize alternative classes that made it to the knockout stage, versus only one EV in the 200-mile range mainstream class.
The hope and plan for electric cars is that the tremendous investment in battery technology will cause the weight and expense of batteries to go down, increasing range and decreasing costs of electric cars. But another way to increase the range of electric vehicles is with VLC innovations: a car that simply takes less energy to move can go farther and faster with a smaller, lighter and less expensive battery pack.
Coming soon, perhaps: an electric Very Light Car.
Reader Comments (95)
Russia is being suffocated with heat and will loose more than thirty percent of its crops. Pakistan is being drowned. Across Australia, tens of thousands of protesters have taken to the streets to urge the major political parties to take action on climate change.
Bold action is needed. In the USA, we have millions of unemployed people who can be put to work building a sustainable energy economy. A 21st century New Deal could solve our economic problems by massively addressing the World's energy and environmental problems.
Very Light Electric Cars can help speed that transformation
Jim Bullis – Kevin here…my last name isn’t Bullis, so I don’t know who Kevin Bullis would be.
JC Briggs – I’ve been thinking about your comments open mindedly, and we are actually both clean energy advocates - but on a few details I just don’t see the optimum path forward exactly the same way.
Regarding weight vs. drag: as I’m sure you know the force of wind resistance goes up with the square of speed (horsepower with the cube), so at low speeds rolling resistance (and transmission losses) dominate and are mainly speed-independent (ignoring accelerations) and at high speed aerodynamic drag will dominate. My comments about weight being of less importance was in reference to cruising on the highway – say 65 MPH. So, I ran some numbers at this speed, to see how it stacks up. Starting with a 100 MPG gasoline car (the same calc’s work for electric) and assuming a reasonably good engine thermal efficiency (35%), the engine is putting out 10.4 horsepower to cruise at 65MPH. The VLC is a little better, I think. Now, subtract ~4% for transmission loss (a reasonable SWAG) you have 10 HP going to aero drag and rolling resistance. This equates to about 58 pounds of forward thrust. Now, if the car weighs 1000 lbs (a bit more than the VLC), the rolling resistance will be in the neighborhood of 6 pounds. In fact, depending on how high-tech the tires are, this figure could vary between about 3 and 10 pounds, but 6 seems reasonable (see: http://en.wikipedia.org/wiki/Rolling_resistance ). So… rolling resistance even for this VERY AERODYNAMIC car is only about 10% of the total at 65MPH. Adding an additional 1000 lbs would double the rolling resistance and only hurt the MPG about 10%, down to 90 MPG. For wind drag to be equal to rolling resistance, speed needs to be approx. 0.3X, or 20MPH. Oliver / Ron Mathis – can you guys confirm actual drag and rolling resistance numbers for the VLC at 65 MPH ?
Regarding Aptera – I’m not sure what speed the calcs were at, but I’ll say that I don’t believe their super-low Cd numbers. Although the body is nicely streamlined – the front wheel struts are pretty bad. Little details make big differences, esp. when they are in front and create turbulence over the entire body. In the XPrize, I’d guess the LOWEST Cd is the Li-Ion, followed closely by Edison2 and eTracer (which has very low frontal area too. It will be interesting to see the real coast-down data (I hope they make this public – will they ?).
Regarding the power grid…well you can find almost any answer you want to hear on the internet. There are so-called “experts” that often have hidden agendas. For example – the power industry would LOVE to have electric vehicles, because they will get to sell into a huge new market (now shared with gasoline providers). Furthermore, they want the government to give them massive incentive dollars to deploy the “smart grid”…which most experts (even the pro-power-industry ones) admit is necessary for supporting masses of eCars. Don’t get me wrong – I think the smart grid is good, and even eCars are good. I’m just a bit weary of distorted facts being used to promote them. Doesn't it seem more practical to try to maximally leverage whatever existing infastructure we have ? (hence my interest in biofuels, which do NOT add net CO2 even though they are burned).
Regarding Wind and Photovoltaic solar power – I think they are great, and we should deploy all that we can. However, what I was trying to convey is that if you view the “big picture” - without energy storage (and I don’t think it will EVER be practical to expect people to provide their own car’s batteries to subsidize the power system’s load-leveling), they can’t practically be our PRIMARY energy source. Solar Thermal power plants can run 24/7, including rapid dynamic load-leveling, etc. Therefore, each power plant can have its cost amortized much more predictably and you don’t need a “backup power solution” for nighttime and peaks and whenever it is cloudy or windless. Also, because Solar Thermal power plants actually run off of heat – even if an extended cloudy time depletes the thermal reserves – you can have a “backup mode” whereby you burn a fuel such as natural gas (or in the future – algae oil!) in the SAME power plant to keep the grid alive during these times (which will always occur unpredictably). Think of the implications if we relied on everyone’s eCar batteries to pump out energy during peak times, dark days, windless days – it’s unworkable on a grand scale (but works wonderfully as long as eCars are a small niche). Also, it’s a free country and you can’t count on people only charging at night (off-peak). In fact, if your work commute is significant (say 50 miles?) then those people will probably HAVE to plug-in and charge at work, during the day, during peak hours, to confidently get home. Anyway – please don’t think I’m negative on eCars, as I’m really not. I just think that mankind needs to put more emphasis on getting the grid greened-up first, and THEN eCars make much more sense. I also think that battery technology isn’t yet ready for mainstream eCars. Some day – yes. We need to focus our limited resources on the most cost effective and expedient way to achieve <the goal> (which again is getting off fossil fuels and eliminating CO2 emissions)…and not just pursue an expensive “cost is no object” choice that while it is beneficial – does not get us to the “finish line”.
Lastly, I think you and I would 100% agree that barring some miraculous breakthrough in nuclear fusion, some form (or probably many forms) of Solar energy is ultimately where we need to go. For this to become our ONLY energy source, practical energy storage on a massive scale IS important. I happen to believe that this won’t cost-effectively be done with batteries, but can be done with energy dense chemical “fuels” (hence my interest in algae biofuel ), and thermal (hence my interest in Solar Thermal). Wind, PV, even geothermal and wave power may all be valued contributors – but the CORE of the energy system of the future needs to have massive energy storage to provide reliable, clean power.
Sorry – I didn’t mean to get on a soapbox too much..but wanted to clarify my viewpoint. Although I have strong opinions, I'm always open to new learning too.
Kevin
Kevin,
I am happy to have the "push-back" in the discussion.
Regarding the relative importance of rolling resistance and aerodynamics. Let me just suggest that one of us is flat wrong. To try to figure out who is right, let me send you my Aptera spreadsheet.
https://www.yousendit.com/download/aHlRT2pFMVgzS28wTVE9PQ
If you go to the tab that says Aptera, you will see at 65 MPH there is 65 Newtons of rolling resistance and 47 Newtons from aerodynamic forces. This is why I have claimed that rolling resistance is important.
One significant difference seems to be our assumptions about Crr. I used a value of 0.0105 and it seems like you used 0.006. Even with this change, rolling resistance is still 44% of the force so it doesn't match what you are saying. So something is wrong hopefully we can figure out what it is.
Additionally, energy efficiency and driving at 65MPH are at odds with each other. Certainly 55MPH is better suited to someone interested in being energy efficient.
Regarding your overall outlook on the grid and EV, I think it is unnecessarily pessimist.
Firstly, there is no reason to think the grid is not ready. EPRI is not some fly by night organization. They say we are ready, then we are ready.
Secondly, what is this obsession you have with storage? It is well known that you can have 30 - 50% renewables on the grid before you need storage. We are no where close to that.
Thirdly, Green the gird first? Why, what is the point. EVs and greening the grid can and will be done at the same time. Greening the grid is already the law of the land in most states.
Fourthly, EVs not ready? Are you serious? Toyota create the RAV4 EV almost ten years ago and most of them are still running. EVs are long past ready.
So you want storage on the web? Why does solar thermal attract your attention so much. So you can store solar energy is salt. That is fine. I have studied this technology and know it is being deployed in Spain at Solar Tres. However, it is only suitable for one type of power, concentrated solar power. If you want to use PV or wind, you need another technology, like, i don't know, batteries. Did you also know that batteries are used now to provide power on the end of some feeder lines just to avoid building new power plant. Battery backup of the grid is possible, it is just the expense that is holding it back. Undoubtedly the same expense will hold back salt storage in concentrated solar. After all, why pay for an unneeded salt storage system.
Save the bio-fuels for airplanes and trucks that are not readily adaptable to electric drive. Personal transport is so well suited to electric drive, it is an obvious fit. The cost of electricity is so cheap (even if from PV) compared to gasoline, electric drive is surely a winner.
Later
John C. Briggs
John C. Briggs,
Everything I say about fossil fuels is not because I am in favor of their use, but I believe that the first step is to be honest about the effects of our decisions. In the end, I strongly advocate reducing the amount of energy we use, but not to the degree that our economies in the developed world can not handle it. Our job is to find ways to reduce fossil fuel use in more constructive ways than by just jumping on the electric car bandwagon.
I was told by a commenter at the Economist magazine that Niagara Falls has to waste power to keep the tourist industry happy. This is only one of the ways hydro is misused. Another way is to use it at any time when it is not producing electricity when it is at maximum value, as during peaking times, and then the ability of hydro power to be turned on and off quickly makes it a highly valuable resource. To build natural gas peaking plants for this purpose is wasteful of public money, if it can at all be avoided.
The decisions to not use coal in California were made by leaders who made every effort to obfuscate the economic reality that would come about from these decisions. I find this objectionable. Autocratic action has happened in the zealous pursuit of green objectives, as defined by some.
I also try to not define who needs air conditioning and who does not. The truth is that the burden of some 'green' decisions fall on many who are not in position to handle it, but decisions to take such actions are made by people who will hardly notice the burden. And the burden sometimes comes indirectly, as in the dis-incentivizing effects of excessive and uncertain power costs on business planners who seem likely to react by expanding business operation elsewhere. How this is playing out in California seems to be a pilot for how things will immently play out nationally. The burden I speak of is that many will not have jobs as a result. And to get ahead of the next comment, no, 'green jobs' are not long term or economically stimulating in nature.
Hydro has a huge potential for storing intermittent energy produced by wind and solar, and it can even do this by simply varying its output, or of course, being configured for pumped hydro storage. Here is a place where government action is seriously needed, and yet does not seem to be forthcoming.
Another of my favorite schemes is to encourage everyone who can to convert from electric appliances to natural gas appliances. By making heat directly at the point where it is needed, the need to waste 70% of the energy in central power plants is avoided. Since use of natural gas in this way displaces coal fired generation the CO2 is cut in half again. Amazing is it not that something this simple could reduce CO2 for this sector by 85%.
Thinking big of course, and this is required, another real change in the CO2 balance can be achieved with natural capture, which can be done on a large scale using expanded forestation. This looks feasible if we could simply work out a system with Canada to utilize their water from the far North for irrigation of the whole continent down through Mexico. Standing forests with wood harvesting for permanent building purposes is a form of CO2 capture that makes serious sense to me. This I suggest instead of the "punish the bad guys" concept that is being considered by the EPA which they call "carbon capture and storage."
Kevin,
You set up some significant starting points for discussions.
You might not have seen the paper by Morelli in 1982 where he described the shape that is close to that used by Aptera. The issue he addressed was the degradation of aerodynamic performance from the ideal that can be achieved in free flow conditions due to proximity of the road plane surface. He was able to start with the ideal teardrop with Cd = .04 in free flow, and modify it so that it achieved about this same low level when about 6 inches off the road. Aptera used a shape like this except for the rear wheel. Over the years, Aptera claimed Cd going from .11 at first to .15 in last report, if I remember right, but this involved the wheels as well. The weight also grew over the years, I think from 900 lb to around 1500 lb now. They also were talking mostly about a gasoline engine until they apparently decided that they wanted to make a good showing in the Xprize, and also that they wanted to jump on the EV fad with its government support implications.
My criticisms of Aptera are that the basic Morelli shape is not very efficient from a volume point of view, meaning that the payload (passenger) space is short for the length of the car. I even object to Morelli's basic decision to make room for side by side seating, though this is somewhat natural as an arrangement given that the vehicle shape has to squeeze down to get the shape effects that stop vortices from forming. I also think that the Aptera decision to keep the car low and use an exceedingly wide wheel base is not an arrangement that will win out in the end, and of course, edison2 may be making a mistake here. After all, race oriented folks might be inclined to think this is a good arrangement, but maybe this is not true for ordinary vehicles.
Everyone,
Thanks for the great conversation here. I hope to get back to more of the interesting points, but time is running out tonight.
John,
Thanks for the response. Nice spreadsheet !
Also - I forgot to give you kudos for "walking the walk" in significant
personal steps to reduce your energy footprint, etc. I've done much less,
but am moving in that direction.
I don't have time tonight...but I'll check it out and see where we may have
differences in Aptera calculations. I think I can use some of the X-Prize
data to arrive at a fairly accurate result. At first blush, I don't think
our rolling resistance calculations are the issue (yours isn't that much
different than mine in the big picture, and mine only used 1000 lbs weight,
so needs to be adjusted upward for Aptera). The Aero F is going to be the
big difference (although my example isn't based on Aptera numbers, it should
be in the ballpark, and my implied "Aero F" is in the neighborhood of 230
Newtons at 65 MPH vs. your 47N. I'll try to dig deeper, let you know what I
find, and will gladly accept my error if I find it. Likewise - maybe you
can check too?
Efficiency or not, in my opinion you're not going to get the average person
to slow down to 55 MPH to save a few MPG. Jimmy Carter tried to force
this...and it didn't work out too well. Using that logic, we can all
trundle along at 35 MPH and get fabulous MPG, but it's just not acceptable
to people's lifestyles.
I didn't say EPRI was fly-by-night, in fact I honestly don't know anything
about them. However, that still doesn't guarantee that they don't have an
agenda. Heck, even the XPrize folks have a pretty heavy pro-eCar agenda
(and have distorted the rules significantly in favor of them, then used
bogus excuses why they did so). Standard & Poor's was considered the top
authority on investment ratings - and they said Fannie Mae and Freddy Mac
were solid only weeks before the institutions imploded. Sorry if I may come
across as pessimistic, but I'm really not - I just don't automatically
believe everything I read. I live in Southern California, and the rolling
blackouts we experience most summers (not this summer, due to lower temps)
is a clear indicator of the thin margins our grid operates under.
Regarding "greening the grid", I guess I should have been more specific what
I was meaning. There are laws pushing new power plants to run Natural Gas
vs. Coal, or (as I believe will become vogue soon) Coal-fired with heavy
smokestack scrubbing and CO2 sequestering. These are good interim steps -
but they are still burning fossil fuels. I'm sure you agree that we need to
get to Solar based with zero (or near-zero) CO2 output. My viewpoint takes
this one step further - that if we visualize using ZERO fossil fuels in the
future - Wind and PV alone won't cut it , we'll need energy storage. That's
not to say that Wind and PV are bad...as they certainly are not. But they
are only a partial or interim solution. I still 100% support wind and PV
deployment - but hope that "someone" wakes up that we need to also work on
deploying Solar Thermal power plants too. Batteries in their current state
honestly could not be used for mass energy storage cost effectively. That's
where the low cost of thermal (salts...or even possibly just huge blocks of
concrete or sand) starts looking really good. Please take the time to watch
the Stanford lecture to which I gave the Youtube link, then please let me
know if it changes your viewpoint at all.
I don't understand why you don't buy into the need for energy storage. Is
our society going to allow a power system that can go down for days or weeks
at a time because the weather changes ? I think not. Again - this issue
doesn't present itself if the MAIN power sources are conventional, and only
the "base power" is wind and PV and there is enough conventional reserve to
load-level. Once the wind and PV gets to be a more significant proportion
(don't know at what setpoint...I'm guessing 25%-35%) - then it all breaks
down because the output of those "green" energy sources have random
variability in output, and in fact will DEFINITELY not put out power for a
significant portion of every day.
Well...I'm still open minded, but I'm pretty well informed - and I think
EV's are still not viable as the "everyman's" vehicle. I guess the public
will prove or disprove that in the next 5 years or so, since the Government
is subsidizing such a huge push to get them into the market.
Let's keep talking - clearly you are informed, as I am, and I like the
exchange of ideas and differing viewpoints.
Kevin
Kevin and John,
You might be talking about the well known joint study by EPRI and NRDC on plug-in vehicles. The actual study report on plug-ins is at:
http://mydocs.epri.com/docs/public/000000000001015325.pdf
It was coauthored by NRDC and paid for mostly by them. It has been summarized and republished in a varietly of articles, including IEEE's Spectrum magazine, that variously endorse the idea that plug-ins are beneficial in regard to CO2.
I urge everyone to skip all the verbage in the article and home in on a little core truth that shows up in Fig. 5-1 of that article. All the great benefits to the atmosphere go away if the source of electricity is coal fired power, and in fact, we would be better off with good hybrids instead. They try to pull the trick that because a plug-in is better than the sloppy cars of the past, it is the right answer for the future. But in fact their own study shows that the hybrid without plug accomplishes more.
They also obfuscate by showing how things might be with all sorts of mythical future power possibilities other than coal. Conventional natural gas systems are also shown and electric power from these will make a modest improvement over the basic hybrid. The report is not forthcoming about exactly what hybrid or what conventional car they are talking about, so I am not sure of their analysis at the detail level, but for analysts trying desperately to justify the plug-in, when they actually show data that destroys their case, it seems sort of believable.
It ultimately comes down to whether we believe that solar, wind, or whatever, will exist in sufficient magnitude that it can respond to a load increase. I contend that we should plan on at least 50 years before there is excess capacity from such things that can be drawn from to charge batteries. I will be there first when that condition comes about.
After we decide that renewables are not viable present realities, the struggle goes to a competition between the large conventional natural gas generating capacity versus coal generating capacity. If the EPA presses forward with the results of their study on 'carbon' capture and storage which would increase the effective cost of a ton of coal by about a factor of ten and the cost of natural gas will be less impacted, the competition could be about even. Though I see this as a government action that would knock the pins out from under the developed world such that nobody will be buying anything, the preferred choice for reduction of CO2 would clearly go to natural gas. It could even be a little better than a good hybrid for CO2 emissions.
With that Figure 5-1, we might take encouragement from the fact that there are still analysts around who manage to stick a few grains of truth in an otherwise phony study.
Many people will want to install Solar PV panels to charge their battery electric VLC. It is a natural combination. Solar PV panels can be purchased retail right now for $1.68 per watt. I just checked the numbers on a 4 kW package, and the cost over 20 years would be less than the basic monthly fee I pay to connect to the Grid. 4 kW of solar panels could fill up my electric VLC every day for 20 years or more.
And the cost of solar power is going down, while the true costs of fossil fuels is going up ...
As pointed out earlier in this thread, fossil fuels cost us several times more than the pump price we pay for gasoline, and the kWh price paid for coal and gas generated electricity. And these pollution, war, and climate change fossil fuel costs are increasing exponentially. We really should be forced to pay all these externalized fossil fuel costs with each gallon of gas and each kWh of electricity we use. Then everyone would come to their senses, and switch to Solar power and electric cars as fast as possible.
Jim Bullis,
It is widely known, and not disputed, that EVs powered from Coal are slightly worse for the environment than conventional ICE cars. No one disputes this. Also, we do not now, nor will we ever, power this country from 100% coal.
So what is your vision for the future? How do you see these issues getting resolve? There are some possible visions of the future.
Vision 1) Just keep cramming new CAFE standards down the throat of car companies. 60 MPG CAFE by 2025 was the latest noise that I heard. That is a possibility.
Vision 2) Natural Gas Powered cars, aka the Pickens plan. Makes a lot of sense. Assumes wind power replaces Natural Gas-fired power plants.
Vision 3) Renewable energy powered Electric Vehicles.
For me, the vision is clear, renewable energy powered electric vehicles. There are no significant technological barriers. EVs, e.g. the RAV-4EV, have been around for something like 10 years working very well and the latest generation of EVs will begin shipping this year. Renewable energy such as Wind is well known and cost effective. 10 cents/KWH. Denmark gets 20% or its power from wind today and it is just getting started. Alternatively, people could just use a lot less electricity in their homes (I reduced mine by 75%) and use that saved electricity to power their new EVs.
There you have it, a vision for the future all it needs is execution. Why stick with the mentality that "nothing is going to change" we are burning coal now and therefore we will burn coal in the future. California has already stopped the burning of coal, others can do it if it is pushed. Also, large amounts of renewables have been installed in this country and others. More can be done. We don't need storage (note the lack of storage in Denmark with 20% RE), we don't need some new invention. We are good to go.
Personally, I think I would feel better if you had a clear vision for where you think you are going. This is far better than finding fault with other visions.
I can see RE powered EVs working, in fact, I can do it on my own without much help. That is what is cool about it. The energy can come from my own little 1/2 acre of suburban paradise.
Later
John C. Briggs
Actually Pickens also sees electric vehicles as the best choice for light transportation, and says natural gas is best for heavy long distance trucking, with domestic natural gas replacing imported oil/diesel. Pickens is of course invested in wind farms and natural gas fields.
Wind resources tend to be stranded, and need expensive new high power electric lines to deliver the wind power to population centers. And natural gas fracking chemicals are poisoning irreplaceable ground water resources.
btw -- carbon black from diesel and coal has a very big global warming impact, especially in areas with snow and ice.
Wind is not necessarily stranded. In Germany they pay more for people to put wind turbines near population centers, In the USA they put wind turbines were the wind is strongest. Hmmm, which makes more sense.
But in any case, wind is competitive. Why fight the one renewable that can exist with little or no subsidy. Why act like other sources of power are flawless? We have an answer, now execute.
And carbon black from diesel, Dude they have fixed that. Low sulfur fuel don't you know. That problem is so two years ago. Next.
OK, Mr. John C. Briggs - I had a little time to go over the Aptera drag calculations and your spreadsheet on same. I'd be happy to forward to you a modified spreadsheet where I tried to correct / reconcile everything to match the data. A big caveat - there really isn't enough info to confidently calculate all this stuff because of the interactions between, say, electrical efficiency, drag forces, speed, Cd, frontal area, and total energy used but I was able to arrive at a reasonably guess.
The original spreadsheet equations were basically correct, but did not include some important details like electrical efficiency. Here is how I got things to line-up with what seemed reasonable. Make sure you are sitting down, because the real-world results are much different. Here's a brief list of changes: 1) The weight is published at 820Kg, creating higher rolling resistance. 2) The frontal area is about 1.85m^2, as validated by Neil Blanchard (I can send a reference). 3) Per the FINALS round XP results, Aptera got 164.3 MPGe (140 in knockout phase), which indicates 20.7 KWh total electric power used for 100 miles (this is a key point, as the spreadsheet needs to net-out to this value).
I had to guess a drivetrain efficiency (96%) and net electrical (60%, which seems low but was necessary to make the numbers work), and a Cd of 0.21. I could guess higher electrical eff. but then Cd gets much worse, and vice-versa.
The net results are that the Aptera averaged about 62 MPH, 164.3 MPG2, had rolling resistance of ~84N and aero drag at this speed of ~182N.
I must say, everything seems about right except for the net electrical efficiency. All I can guess is that the batteries got pretty hot due to continuous use (Tesla makes a big deal about their battery cooling system vs. efficiency and performance), and maybe their charger and/or motor controller and/or motor is just not that effiicient. If you can somehow get me your email - I can send the support info.
Kevin
Kevin,
Thanks so much for taking the time to do this. If you can forward the spreadsheet to
John C Briggs
a t
r c n
d o t
c o m
I would very much appreciate it.
Thanks
John C. Briggs
I'm looking forward to the details of how Edison2 are implementing the electric drive train! I'm assuming that they are keeping the rear wheel drive of the current VLC, because it is integral to the way the suspension works?
Also, where is the battery pack located?
Sincerely, Neil
One more comment on my Aptera spreadsheet analysis - the rolling resistance and aero drag become equal at just over 40 MPH, then of course aero starts to dominate at higher speeds. I need to think more about the seemingly low net electrical efficiency. This eff. is actually a STRING of multiplied numbers (say, 0.9 for electric motor, 0.9 for charger, 0.9 for motor controller, 0.9 for battery loss)...which gets close to 60% net. It could be that the new elect. eff. is higher, but that would imply an even higher Cd (I guessed 0.21) or lower mechanical eff. (I guessed 0.96). I'm still comfortable, however, that the "rough focus" of the results are correct, and they support the following statements:
1. The aptera Cd is not as low as they says
2. The net electrical eff. is not that high. In fact, if you multiply the 60% elect. eff with the ~50% power plant eff - the TOTAL fuel (in power plant) to wheel efficiency is similar to a pretty good fuel-burning engine (30%-35%). I guess I ignored power line losses, but this is only ~6%.
3. The weight of the Aptera creates enough rolling resistance to significantly hurt mid-speed efficiency, but at highway speeds, aero drag still is the biggest user of energy.
cheers,
Kevin
John C. Briggs (and Kevin regarding the later parts of this comment)
You miss the important distinction between 'conventional ICE cars' and 'well designed hybrids'.
Almost anything is better than the 'conventional ICE car'. And even a coal fired electric car is better than this. I consider the hybrid as exemplified by the Prius to be the reference for the future that makes discussion about where the next step should be a meaningful discussion.
My main concern is with the trend to put electric systems in the same muscle cars and mommy wagons that we now mostly use, and claim some environmental progress. That will accomplish the objective to get off foreign oil and shift to coal instead. That might be what will happen.
I mostly concur with the way forward suggested by the Edison2 folks where the actual energy to go fast is much reduced. Then it is not so important how the energy gets to the car.
Thus, what would I suggest?: I advocate completely rethinking the automobile; start with real requirements that are driven by real life style choices. This leads me to think that aero drag needs to be seriously changed at the expense of the 'familiar'. We have long known that the airship body form is the most aerodynamically efficient form known, from a volume point of view. In the frontal area formulation, the Cd for this is about .04, for the lengths in question. The main impediment to use of this form in motor vehicles is the proximity of the ground plane. Taking a look at how this might be managed; it comes up that by simply elevating the vehicle by approximately half the width, the ground plane effect can be mostly eliminated. (Morelli 1982 showed data related to this elevation requirement.) Rather than go to the extreme shape of the Aptera, or the wide wheels of both the Aptera and Edison2 designs, I see the possibility of dealing with the wheel wells and proximity of wheels through use of wheel trains over which an airship form is held by struts. If we cut the width down by insisting on single wide seating, all this works out fairly well. We will not see a Cd of .04 of course, but we should see something around .07 for the whole thing if the wheel trains are formed as single aerodynamic entities on each side. It seems like sound engineering to accept a little more weight than the Aptera even, in order to get this kind of aerodynamic gain.
My examination of many failed attempts to change the car going back to the cycle cars of 1915 and all the way through the Messerschmitt, Isetta, and microcars of all sorts, suggests that people simply do not want to ride 'puny', looking up at the undersides of trucks and having no sense of adequate visual perception, as they drive down the road. It is hard enough to break with the sense of fashion that motorists attach to their cars; to ask them to drive in a perceived unsafe configuration is going too far.
I also see an issue with the widely space wheels of both the Aptera configuration and the Edison2 configuration. Separation of wheels from the main car body has merit in both cases, but separation can also be achieved by raising the main car body above the wheels. Yup, it sure looks wierd, and does not call up the excitement of race cars.
That's an interesting point that Edison 2 posted on an article on an earlier blog. People's reasoning behind driving an SUV for the reptilian response of bigger = safer, and the myths behind it. I read the article thoroughly, and it made me quite depressed about American drivers. Apparently, one of the most likely to live from a car crash is a Honda Accord, and one of the least likely a driver would survive, and or avoid a crash is a Chevrolet Trail Blazer. The Chevy weighs in at a hefty 5,750 lbs. The Honda weighs in at an average 3300 lbs. The article went on about other things defining safety to consumers, from how high up off the ground, or at least how perceivably high, to how many cup holders the car had, to how the PT Cruiser was modified, because it was found out that women felt safer in a car where the person behind them couldn't as easily see in, so they made the rear window smaller, etc. All of this is to say, maybe what we all need to do is instead of buy a product because of the advertisements, we should buy based on a true analysis and rational decision of why we bought what we bought. If people started doing that alone, efficiency, performance, safety and ergonomics would all go way up on new cars. Feature creep, paid celebrity glossy advertisements, twelve air bags, and twelve cup holders would all go away naturally.
That way, when you buy a car, and someone asks you why you bought it, you will have real, and substantial evidence.
The reason I have a 2000 dodge neon is because it has the best gas mileage of the family hand me downs I've been given. In other words it was a free car with relatively decent fuel mileage. The other one I was given was a 1993 Mazda RX-7 twin turbo road rocket. I sold it to finish paying for my college. If you really want to know the truth I wouldn't have sold it just because it only got 12 mpg.
I have yet to pay for a car, but I will know exactly why it's a good car, when I buy one.
biologist 111, you are a truly sensible person. Nobody should get carried away and do things that do not make sense for their circumstances.
My 1991 Acura Integra is humming along with a few non-fatal wounds, and costing me just a little more than the insurance every year, to keep it going the few miles every year that I require of it.
If somebody needs a Yukon, they should darn well go get one.
I am only talking about how things should go in the future, long range and as a matter of public interest. When trade-in time comes around, then perhaps sensible decisions will be made. But I hope by that time we will have rejected the silly traditions born of mind bending from advertising and custom set by mass tendencies.
John C. Briggs,
Fuel for wind systems is truly competitive.
Capital costs seem quite another matter. Sloppy accounting is necessary to make it competitive. How do we know? -- Investors will not touch it without free money from government. And by the way, Pickens the Pocket canceled his wind turbine contracts, for reasons that we can only surmise to be along the lines I suggest.
One particular difficulty with wind is that the system that involves this source also must provide for intermittency, and the backup storage that must stand by for slack conditions has to also be funded as a system part.
A string of interconnected offshore turbines along the 2,500km East Coast could provide steady supply of wind power. Studies show that low wind in one area would be balanced by high wind in another -- "And previous research has shown that offshore wind power alone could supply the needs of coastal states".
quoted news story written by David Biello:
"The problem with generating electricity by harnessing the wind is that it doesn't always blow (though it may seem that way at times). And, typically, consumers remain intolerant of power interruptions.
But there may be a way to ensure a steady supply of wind, according to a new study in the April 5 Proceedings of the National Academy of Sciences. The key? Sea breezes (and a lot of expensive wiring).
Willett Kempton, director of the University of Delaware's Center for Carbon-Free Power Integration, and his colleagues analyzed wind patterns from 11 sites on the U.S. East Coast, along the 2,500 kilometers from Maine to Florida. By wiring together hypothetical offshore wind turbines along this coastline, the researchers found that they could guarantee a steady supply of electricity. In fact, according to their model, there would never be a time when the wind wasn't producing some electricity—and previous research by Kempton has shown that offshore wind power alone could supply the needs of coastal states.
Of course, no offshore wind turbines exist anywhere off the U.S. East Coast—and reactions from coastal residents have been as mercurial as the wind, depending on whether one resides in Cape Cod or Cape Hatteras—so this exercise remains entirely theoretical. As it stands, the roughly 2 gigawatts of offshore wind turbines proposed along the East Coast are largely planned to operate independently. And the longest (and most expensive) high-voltage direct current cable ever laid spans just 580 kilometers. The researchers estimate the cost of the cable alone for this plan at $1.4 billion (though that is only 15 percent of the cost of all the offshore wind turbine installations).
But should this abundant resource be tapped, a unified grid of offshore turbines could help make wind power reliable. After all, as Kempton et al. wrote: "There is almost always a pressure gradient somewhere, and cyclonic events move along the coast."
Jim Bullis,
Wind power is producing electricity at 8 cents/kwh with something approaching 1.5 cent/kwh support. That support can come from the government or rate payers. This is not exactly expensive.
In Europe, most wind turbines are "community based" meaning that groups of individuals, e.g. farmers, pool money to buy the wind turbine. This is supported by a FIT (feed in tarriff) of about 10 eurocents/KWH. Again, not very expensive.
The US efforts in wind have been hurt by the economic slowdown and the US's decision to support wind with a PTC (production tax credit). This means you can only benefit if you have tax obligations from another business. During the economic meltdown, corporations had losses and could not use the PTC. In Euro, with the FIT, no such problems exist.
Also, I don't know why you insist on talking about storage. There is a lot of wind both here and in Europe. Note that storage is not needed. There is something called "baseload" that exists all the time. Until that is exceeded, no one will pay for storage.
Variability in both supply and demand is something grid operators deal with on a day to day basis without storage with very few exceptions. There is some "pumped storage" hydro systems and some battery systems. These are usually used on the end of long feeder lines to boost voltage.
I think there is a lot of false understanding about how the grid works. Every KWH of electricity that is produced each second is consumed within that second. The grid remains balanced at all times. Your refrigerator kicks on, and the power plant must put out more juice to support it. A wind turbine spins a little faster, a gas turbine must cut back to compensate for it.
What you have sir is a "fear of intermittency". The fear among some guys that someday the wind will stop blowing and they will be left in the dark. But with a little counseling, perhaps some group therapy, you can overcome your "fear of intermittency".
Later
John C. Briggs