The Ergosphere
Tuesday, July 18, 2006

Nothing will be enough if you keep wasting it

Over at GCC, there's news of gasified biomass to ethanol getting some attention.  114 gallons per ton isn't too bad, roughly 9.4 GJ/ton LHV; if bone-dry biomass has 16 GJ/ton, that's close to 60% conversion efficiency.

The only problem I can see with this is that it's aimed at the same old dead-end consumption technology:  the internal combustion engine.  The claimed 1.3 billion tons/year of available biomass (at the same 16 GJ/ton) contains 2.1e19 J or ~20 quadrillion BTU of energy.  Turn that into ethanol at even 60% efficiency, and you cut that to 12 quads.  Compare to roughly 18 quads of gasoline we use each year!

The USA is currently using about 40 quads of oil per year, plus maybe 25 quads of coal.  But we only take about 6.8 quads of electricity from coal, and the 45% of petroleum which becomes gasoline supplies us with a mere 2.6 quads of work at the wheels.  That totals 9.4 quads, or a bit over half the energy in that biomass.  If we could turn biomass into work as efficiently as we can turn it into ethanol, we'd be there already.

Why do we get so little from so much?  Briefly, it's because we haven't yet moved beyond the Otto-cycle engine and simple steam turbine. This leads to two conclusions:

  1. We are not going to replace coal and oil by turning biomass to liquids.
  2. It's still possible to replace them with biofuels, but only if we break out of the "gotta have something to pump" mindset.

Somehow we have to convince people that they have to charge with electricity instead of pumping a fluid (or, heaven forbid, fill something with carbon granules!), or the future is going to be a lot worse than the past.

Are you saying that 300-mile range and 5-minute recharging isn't good enough?  (That's what you could get with A123systems Li-ion batteries in an AC Propulsion tzero.)  Even lead-acid looks pretty good if you replace all the lead used for mechanical backing and electrical connections with something like carbon foam (Firefly Energy).  Don't forget that you're eliminating the engine and all its weight.

So then you say "high-performance batteries aren't cheap enough to do the job affordably."  For the moment, you're right.  But we can use fewer batteries to run the first 10-20 miles of every trip using PHEV's.

PHEV technology can reduce liquid-fuel needs by about 80%, with a combination of conservation by greater efficiency and outright replacement with electricity.  If we consider the biomass resource as being 1.3 billion tons of (CH2O)n (40% carbon by weight) and get 30% of it as charcoal, we're left with 130 million tons of carbon in the off-gas.  If we can capture 80% of that off-gas and turn it into ethanol (using e.g. one of the algal schemes being developed), that would make about 200 million short tons (229 billion liters, 60 billion gallons) of ethanol.  If we'd managed to cut our liquid-fuel needs by 80% to 28 billion gallons a year, 60 billion gallons of ethanol (equivalent to about 40 billion gallons of gasoline) would do the trick with some left over.

This is doable.  Not easy, not in the least, but it's doable.
On an almost totally unrelated subject, one thing that has always intruiged me is why it takes energy to partly cancel the effects of the sun's energy (eg, why refridgerators and freezers need power). It's cool where the sun isn't, right? Depending on your power source, we are using energy to get oil, refining it and burning it ... all to generate energy to partly cancel out the effects of the sun's energy.

I think this kind of thing is what's going on with the business of trying to replace 'petroleum' rather than rethinking the whole thing. It's dangerous to get stuck in a mindset.
Excellent comments, thomas and E-P. 20kg of A123 batteries in a PHEV that would handle 90% of my driving without starting the ICE sounds pretty good to me. (I do mostly short trips, somewhat atypical I admit.) Anyone know what those 20kg of batteries would cost me, now and in a hypothetical ramped-up production future? (I suspect Toyota will more or less answer this question for me some time soon, though not exactly A123.)

Does there exist a gasoline or diesel generator with the necessary smallness, lightness, quietness, power, and efficiency to stick in the back of a pure EV to provide range? This could obviate the need for the 600kg of batteries that would provide the 300 miles of range that everyone thinks they need, but almost never use. Since you would be getting rid of the engine, transmission, and a few other parts of a conventional hybrid, there would be a lot of mass, volume, parts count, and money to play with. Seems like a huge win to me. What's the catch?
Gitch:  Unfortunately, the antecedent isn't true.  It often IS hot where the sun isn't, because heat moves by radiation, convection and conduction.  About the only things I've heard of which keep stuff colder than ice-cold without power are some IR cameras on mountain tops, which use their position above most clouds to radiate their excess heat to space.  They shield the radiators from the Sun, of course.

You can use heat to generate cooling; one method is the absorption refrigerator.  Unfortunately they don't appear cost-effective at the moment.

George:  Easily done with a generator trailer.  Even AC Propulsion did it.  They appear to have picked a rather inefficient engine, though.
The AC propulsion trailer is a bit of a head-scratcher. 30-35 mpg seems awfully low. They used a 20 kW generator, which seems like overkill. I recall hearing that maintaining a steady 60 mph required something like 6 horsepower in a smallish car. For something with great aerodynamics and tires, that sounds reasonable. Maybe you need 20 kW if you want to do 70 up Cajon Pass all day with the AC on, I dunno.

Does anyone know where to find the power requirements for various operating modes of a reasonable car, something ranging from a Honda Civic to Accord? And how much power would a decent air conditioner need?(I would guess close to 2 kW; cars need a lot of capacity for rapid cooldown, given that they are basically mobile solar collectors.)
Nick, it's a lot more expensive to design a hybrid vehicle than a pure electric.  Getting rid of the ICE powerplant and its fuel means you have no expenses related to emissions, to name just one advantage.

That expense goes to the generator-trailer instead.  Or maybe it does; it may not have to meet crashworthiness requirements.  One trailer design may do for many vehicle lines.  This is one problem which may be best solved by the Unix philosophy of "do one job, and do it well".

And yes, AC Propulsion's efficiency seems low.  I calculated fuel consumption on the order of 0.64 lbm/HP-hr (about 390 grams/kWh).  I think they were looking for light weight or small size, and efficiency took a back seat.
EP: I think you might have taken my comment a bit too literally. I know that it isn't always cold where the sun isn't. If that were true, a piece of land on the earth would fall to absolute zero moments after sunset! What I meant was in a vacuum in space, far from the sun... it is cold. As a general rule, the further a planet is from the sun, the cooler it will be.

We have gas-powered refridgerators now. I'm not saying they're not possible. I'm just saying it's a silly concept.

Maybe if we weren't so hung up on releasing potential energy by burning stuff all the time, we might be able to move forward.
"It's still possible to replace [coal and oil] with biofuels" -- if that were true, it would mean biofuels could defund fossil fuel tax revenue takers, a group I like to abbreviate as petrolists.

Biofuels would then necessarily not have the backing they do. Round and round we go.

How has your opinion of miracle-metal zinc evolved in the past year?

--- G. R. L. Cowan, former hydrogen fan
Boron: internal combustion, nuclear cachet
Gitch:  Since all of humanity lives on or very close to Earth (and will for the foreseeable future), I have to ask you to explain why you thought that relevant.

Mr. Cowan:  That does a very nice job of explaining why there is strong government support for hydrogen (most easily made by reforming natural gas and gasifying coal), does it not?

Zinc and charcoal look like strong competitors.  Charcoal/DCFC is more efficient, zinc-air is less dependent on any one energy source.  Either one is a huge improvement over the status quo.
I was checking out the Tesla roadster. Nice.

But one thing I found interesting... the "WTW" efficiency was about 135 mpg equivalent. That is less than I expected. Probably not much better than a plug in hybrid (especially if it were a diesel hybrid run on biodiesel).

Almost certainly less than a Loremo (of course no Loremo will go 0-60 in 4 seconds either)... especially if the Loremo is powered with, say, biodiesel (isn't the EORI for biodiesel like 3 or 4:1?).

Doubtless this is because of the lower weight of the Loremo (less than 1/2) and the lower emphasis on performance.

And that's without any kind of energy capture system (like the pneumatic system you discussed in the comments of the last post.

The Loremo will be pretty cheap, comparitively, an energy capture system shouldn't add too much weight or expense.

Maybe a small flywheel system would be even cheaper than the pneumatic system. I don't recall how to calculate how much energy that could be stored in, say, a 100lb steel or lead disk at a reasonable RPM (college physics was a long time ago, and Damnit Jim, I'm a doctor not an engineer).

If oriented horizontally at the lowest possible point the gyroscopic action might actually help stabilize the car in turns (preventing body roll) though the strength of this effect would change at different flywheel rpms and that might actually throw off the driver.

Basically, I'll be in the market for a new car in a few years, and I'm trying to decide which direction to go. I could probably buy either type if I wanted.

Maybe the "Loremo" direction will be a tech branch for the less affluent, and the EV route more for a wealthier "status" crowd... at least for a while.

I'm convinced that eventually we'll go all electric once the tech gets there.

Finally, I read something a little while back about the zinc-carbon process being trialed somewhere (Israel?). Have you heard anything updates on how that is working out?
Tesla Motors claims 2.18 km/MJ (205 Wh/mile), so if all US gasoline-powered vehicles were replaced with them for our 3.1 trillion miles/year of driving, they would consume 636 billion kWH of electricity.  That's a little over two times 2004's total US production of renewable electricity, and quite a bit less than what we get from nuclear.

I think we could manage very well with 135 MPG equivalent.

I haven't been following the zinc saga closely; I've been busy with other things, and have barely had time to blog the small stuff.  If you see something, feel free to drop me a note.
EP: I did start with a disclaimer about how related the subject may/may not have been... but the point I was trying to make, albeit unsuccessfully, was that trying to replace oil for the purpose of powering ICEs is becoming a long chain of sources, pretending to be the previous source.

For example, obtaining chemical X, extracting it into chemical Y, and burning it inside an ICE (as opposed to just starting with chemical X and taking the energy directly out of it in the form of a fuel cell to power an electric motor). It's like having a whole lot of computers running emulation software. Because we've always had to do this to get gasoline in the past, we're simply trying to continue it.

The 'sun analogy' was to try and explain this. As opposed to using the sun's energy directly to create the cooling, we're putting it in from an external source. I'm not saying it's physically possible to do this. I was just using it as an example.
My bad.

As for the misunderstanding, I plead lack of time to go back and re-read things.
(the previous comment was addressed to Gitch.)

Hamerhokie, I agree with you that alternative fuels could theoretically accelerate our switch away from petroleum.  But that's in theory; in practice, ethanol is being used as an excuse to keep Americans buying gas guzzlers, and the subsidies placed on it divert interest and investment in those very electric vehicles we need.

Look at it this way:  ethanol today accounts for perhaps 2.5% of the energy supply for light vehicles in the USA.  We pay a large amount of subsidy money to get this.  We could obtain the same 2.5% or more for zero investment by training drivers to coast up to red lights instead of racing to them.

I cut my fuel requirements by about 1/3 when I bought my last car.  I can cut them another 5-10% by driving at 60-65 instead of 70 on the freeway.  This is a lot cheaper than any alternative fuel I've seen so far (with the possible exception of biodiesel from waste cooking oil).  Unfortunately, the cost of ethanol is paid by everyone and not just the people who use it.
I've been hunting up some information on inductive power transfer. It seems some early prototypes and calculations were actually tested full scale in the 1990's. The efficiency of the power transfer was 60% to 65% (with potential improvements), and was called "While these efficiency levels are lower than one would expect for a conventional battery charger, the comparison between the two becomes more nearly equal when one considers the efficiency on a complete system basis..." since you no longer had the charge and discharge cycle.

Electronic, wireless control has come a long way in the last five years. It would seem feasible to create a switched, individually billed, road power system based on induction. It could have knock-on effects for safety and efficiency if it were combined with steering automation and some kind of speed control.

At least then you could reliably drive your car across Saskatchewan or Wyoming.
Except that places such as Saskatchewan and Wyoming get cold in the winter and highways are prone to suffering frost-heave damage. Burying cables in the highways would be really expensive. You're better off having overhead lines, such as what electrified rail lines use. There's actually still some electric trolly buses here in Edmonton. The overhead lines are ugly, however.

The various dual-mode road/rail transport concepts that Engineer-Poet and myself have discussed on our respective blogs are probably a better solution in that you can separate the passenger and freight transportation routes.
Not to mention the fact that a road full of electromagnets is going to be lawsuit heaven given the paranoia about EMF's.

IMHO, if you're going to transmit power with electromagnets you might as well use them for levitation as well.
Just thought I'd float the idea for an opinion. :) I'd add to your the critique that one would basically be introducing a third power system to the drive train (assuming we're starting with a hybrid), with its own transformers and control circuits. That's going to be extra weight, complexity and problems.
I hope those Saskatchewanians and Wyomingers are sending care watt-hours to California.

(Will somebody shut off those sirens. No, no, not the warning ones, the klieg lights over in tinsel town. Maybe we can get it down to a reasonable energy emergency rather than a disaster movie.)

I am sure that when EP gets the time he will be signing up for a Tesla. The Guv sure looked good riding in one. Hm, I wonder if ENRON as a vanity plate has been taken?
I'm sure I'd have tons of fun in a Tesla, but if I had that kind of money the first thing I'd get would be a Prius+.
Here's a page with some Solzinc updates:

It looks like they have a paper in the works confirming the 30% conversion efficiency claimed (which met their target) for the pilot plant... producing about 50kg/h of near pure zinc:

So it looks like the pilot study went as planned.
Great news.

For the convenience of readers, here's a hotlink to that abstract.

I still await someone responding to the McLeod hypothesis: What is the EROI of biodiesel from snake oil?
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