Miles Per Gallon Equivalent by Four Different Methods

[NeilBlanchard]

The reason to use MPGe is to compare the efficiencies within the vehicle. Not to compare the entire energy cycle.

If you get your electricity from solar panels on your own roof (or feed an equal amount of energy into the grid during the day, and use it during the night to charge your EV), then how would you compare it to a petroleum based fuel car?

Of course, if you raise your own sunflowers of jatropha, or have a diesel excreting bacteria patented, or even if you have a source of old deep frying oil, then you can ask the same question.

The Illuminati Seven has driven nearly 200 miles on just over 32kWh; which means it got about 217MPGe at highway speeds. The TW4XP has about 85% plug-to-wheel efficiency.

Once you have a renewable energy source, then you don't even have to worry about how efficient it is. We need to move to EV's (and biodiesel) so we can transition away from using billion year old sunshine. We need to use the "youngest" sunshine as possible.

Even if EV's are worse carbon users than gasoline powered vehicles (they are not worse), then we still need to make this transition. Because electricity is locally produced, and at the very least, all of that money we pay for it stays in our local economy.

We spend at least $1 BILLION DOLLARS PER DAY on oil from other countries.

We also have had untold subsidies of oil -- not the least of which is oil is traded in US dollars. Remember the "Axis of Evil"? Those three countries changed to trading oil in Euros, and if more countries did this, it would cut us off from the demand for US dollars. We essentially are buying oil with the "profits" of all those oil trades, because they must be done in US dollars.

If all oil was traded in each country's own currencies, then I think we would see the US change it's habits rather quickly.

[dcb]

Originally Posted by NeilBlanchard

The reason to use MPGe is to compare the efficiencies within the vehicle. Not to compare the entire energy cycle..

But since it ignores the major heat-loss conversions at the electric plant, which is a major part of the grid, it does a horrible job of it. You give people a "dumbed down" figure like 135mpge and they will draw the wrong conclusions.

[mnmarcus]

Neil,

I disagree with this;

The reason to use MPGe is to compare the efficiencies within the vehicle. Not to compare the entire energy cycle.

Most people (me included) would probably say, "MPGe compares the cost in electricity versus gas."

Maybe I shouldn't disagree, maybe MPGe IS to compare the efficiencies within the vehicle... It's just that I don't care about that only, it's a neat parlor trick but the real story is hidden behind a giant curtain. It's the same as a hydrogen powered car, "great! no emissions at the tail pipe." If we all drove hydrogen powered cars would we end CO2 emissions? No. In the end we (as a planet) would be worse off driving hydrogen powered vehicles today.

I'm surprised you don't want to compare the entire energy cycle?!?
I'm also surprised electric plants seem so inefficient! dcb??

The TW4XP has about 85% plug-to-wheel efficiency.

I couldn't verify this, I assume its true. So it's 92.2% efficient at charging and 92.2% at running?

Once you have a renewable energy source, then you don't even have to worry about how efficient it is.

Maybe if it was an unlimited, totally clean, instantaneously renewable resource. I'd still probably wonder what the catch was.

Jokingly: Does anyone think oil IS a renewable resource? I mean has the planet stopped making it? Also to be truly carbon neutral shouldn't we drill, pump and burn all the oil we can, there by "releasing" the CO2 trapped for billions of years by prehistoric plants? - I'm joking, but maybe something to think about?

I think we all have our individual points of view or preconceived ideas. Mine include the efficiencies of turbo-diesels and hydraulic regenerative braking, minimal frontal area and aerodynamics.

We also have our own "strengths" and "weaknesses". But those weaknesses aren't truly weaknesses because each of us shares them with millions of others on this planet. I was blasted for not knowing the most efficient heat transfer device, but so what? I'm not an engineer. I'm a designer. I visit this site primarily to learn, and maybe to share some thoughts that may be of some benefit.

[NeilBlanchard]

I do want to do a source-to-wheels comparison; but this is pretty darn difficult to do. All the numbers I have seen put EV's well ahead of gasoline; even if you have 100% coal generated electricity. And the fact that you *can* get electricity renewably -- which is impossible to do with gasoline; makes it get better and better as we move to renewables for electricity.

The reason that I have heard stated against MPGe is that it isn't "fair" to ignore the source of electricity -- and for pollution considerations, I agree. BUT, the *same* thing must be applied to gasoline, to be completely fair.

So, MPGe based on BTU's works fine to compare the relative efficiencies between vehicles. But for carbon footprint comparisons, a lot more has to be done.

[mnmarcus]

Ha Ha

The reason that I have heard stated against MPGe is that it isn't "fair" to ignore the source of electricity -- and for pollution considerations, I agree. BUT, the *same* thing must be applied to gasoline, to be completely fair.

I now tell my kids the exact same thing my dad used to tell me "Life ain't fair!" I don't know if its fair or not. I'm interested in CO2 emissions, cost per mile (including purchase price and repairs/replacement), and lowering dependence on foreign oil. MPGe doesn't really tell me much... Unless it says how much I save per mile versus driving a gaser.

Sounds like I get what you are saying, I think you get what I am saying too. Guess maybe I thought everyone interested in EV was a "crazy" environmentalist. From a per mile energy $ EV is king! I'll give you that. Electric is cheap and driving an EV is too. Buying one? Definately not cheap.

I have begun to think more about the possabilities of an EV, especially with hydraulic regen braking and "boost" assist.

I think IamIan had the best post, he looked at MPGe in like 4 ways... Maybe we need a bunch of MPGe's. MPGe$ how much it cost to drive per mile -vs- gas. MPGe$A how much it cost to drive versus a gas version figuring in the extra initial cost of the EV and the depreciation of car and battery packs. MPGeCo2 could be the carbon footprint version. MPGeBTU could just look at the thermal efficiencies... MPGeMAX could be the range... That doesn't make sense.

[RobertSmalls]

Originally Posted by mnmarcus

I think IamIan had the best post, he looked at MPGe in like 4 ways... Maybe we need a bunch of MPGe's. MPGe$ how much it cost to drive per mile -vs- gas. MPGe$A how much it cost to drive versus a gas version figuring in the extra initial cost of the EV and the depreciation of car and battery packs. MPGeCo2 could be the carbon footprint version. MPGeBTU could just look at the thermal efficiencies... MPGeMAX could be the range... That doesn't make sense.

The first post of this thread also agrees with IamIan on that point.

[roflwaffle]

Originally Posted by dcb

but that is an arbitrary point in the system, ignoring all the conversion losses to that point (which are many), from the days when all there was was gasoline basically, and puts the alternatives at an unfair disadvantage.

I think that saying it's an unfair disadvantage is going a bit far. It's a somewhat arbitrary distinction because it's from the past, but considering we've been using it for decades complaining about it now is kinda silly IMO.

Originally Posted by JasonG

With liquid fuels it is figured in. For every X gals extracted from source Y, Z number of gallons is used in purification, processing, transportation etc. The 1 gal in your tank started as 1.X gal.
It's the reason alcohol from cellulose is impractical. It takes more energy to produce than it provides to the tank.

The EPA's mpg figures do not take into account the energy needed to extract, refine, transport, and so on, oil/gasoline AFAIK. All forms of energy need to be refined/altered and require more energy put in than we get out, that alone doesn't make alky from cellulose impractical. It's more about the economic considerations than anything else.

[user removed]

Originally Posted by RobertSmalls

Ah, here's the study from Dr. Samaras that I was thinking about. http://solar.gwu.edu/index_files/Res..._for_PHEVs.pdf

Here's a Green Car Congress digest of the paper:

Green Car Congress: Study: Meaningful GHG Benefit from PHEVs Requires Low-Carbon Electricity

@Neil: I have addressed each of your points in my OP.

Using this graph as the basis for a comparison (seems like it reflects most of the real costs and effects) I think we need to think in terms of each system individually.

Short term improvements.

Long term improvements.

As yet unrealized but possible future technological breakthroughs.

The most effective short term improvement that requires no technological breakthrough should be the first order consideration and implementation.

Idle elimination
Regenerative braking
Limiting engine operation to only highest points of BSFC (all or nothing).
Aerodynamics
Rolling resistance

These are in vehicle improvements that I feel should be mandated or a least seriously encouraged cost wise.

Virtually every source of renewable energy is primarily based on solar (even petroleum) or lunar (tides) and geothermal (subterranean heat) sources. Properly utilized these various sources of conversion and capture represent many times more power than required by the total population of planet earth today and for any reasonable period in the future.

I disagree with any statement like, "since it's solar energy, efficiency is irrelevant". Everything is relevant, cost, life expectancy, break even points, all of those factors are totally relevant. The solution is to render them irrelevant by resolving the issue with better design, that is less complicated, less repair intensive, and provides a break even financial return time period that no sane person could argue against rationally.

As I read the various threads it becomes apparent that many here believe that this or that method is the best pathway to success. Some are convinced that electrification of transportation is imperative and fossil fuels are poison. Others think electrification is a future means of transportation that requires some more "breakthroughs" in development to accomplish the goal.

As far as how we measure consumption. I find the graph in my quote to be a decent representation of the overall costs at this point in time, and this point is what is relevant today.

ANY MEANS OF IMPROVING ANY INDIVIDUAL DESIGN AND REDUCING THE OVERALL COST IN CARBON IS SUCCESS AND SHOULD BE RECOGNIZED AS SUCH.

Priorities and agendas will never be a solution, but will certainly be an impediment to the two primary issues.

Energy independence
Pollution reduction

While we can debate (or stupidly argue) the priorities, the real goal remains elusive to those who only focus on something like how we measure consumption of any energy, when we should focus on maximizing the benefit of every btu of energy we use for any purpose.

I read a book a long time ago about a Japanese submarine Captain in WW2. His boat was the I 15. When they pulled into the docks near the Burma oil fields the light sweet crude was pumped through a filter separator, directly into the fuel tanks of the submarine. I could use that point to argue (stupidly) that that represents the lowest cost to provide consumable fuel to transportation.

What is the future? No one really knows, so why not just consider the most practical short, medium, and long term solutions, with the priorities that we can agree on as providing the best solutions that are economically feasible and practical. Future developments, especially something as significant as an inexpensive long range, cost competitive, battery powered car, would absolutely change the priorities as far as where development and implementation of vehicle design was concerned.

My question is why do we allow some very simple improvements that require no technological breakthroughs, to remain utilized. The most glaring of the two are engines that idle, and brakes that convert precious inertia into more wasted heat energy. Those two examples alone if implemented NOW would go a long way in the right direction. They are fairly simple. I am not talking about hypermilers who minimize those two glaring defects through intelligent operation, as hypermilers represent the smallest minority of drivers.

It goes to the philosophy of blame the system. I know some do not agree, but the system (vehicle) as the focus of applied technology will be a much more effective way of accomplishing the ultimate goal, than any dream of retraining the driving population of planet earth.

Is this off topic? Well, maybe so, but doesn't this thread demonstrate that we all have agendas and priorities which serve to cloud our opinions and create a lot of noise which serves only to disguise the real issues.

regards
Mech

[roflwaffle]

Originally Posted by mnmarcus

I'm also surprised electric plants seem so inefficient! dcb??

It's pretty accurate for coal, ~32% on average. Natural gas is higher at ~43%, and nuclear is between those two, although in the context of Carbon emissions it's essentially Carbon free like renewables.

[UFO]

Originally Posted by roflwaffle

It's pretty accurate for coal, ~32% on average. Natural gas is higher at ~43%, and nuclear is between those two, although in the context of Carbon emissions it's essentially Carbon free like renewables.

Until we make concrete with renewables, nuclear will not be carbon free. Nuclear construction requires mass quantities of it, and more when it's decommissioned. But averaged over the energy delivered, I don't know how significant it is.