Dear Mr. Khosla,
I hope this letter finds you well. I have no doubt it finds you wealthy.
You appear to have taken a position in re: ethanol, claiming that it will provide "the solution" to our petroleum woes. This has been challenged. Robert Rapier has already done a nice job of debunking the claims you've made. I'm just a pseudonymous analyst (and an amateur at that), but I hope that you'd explain the details behind what you've chosen to acknowledge versus what you've chosen to disregard.
The implications of what you've chosen to disregard are considerable. Your position (please correct me if I'm wrong, I cannot view your video presentation) appears to be this:
I've done the math, and I can't see how you justify this position.
For background, the USA uses approximately 20 million barrels of crude oil per day, 7.3 billion barrels per year. At ~6.1 gigajoules of energy per barrel, that's roughly 44 exajoules (42 quadrillion BTU, or quads) per year.
That's a whale of a lot of energy. Even the fraction used for motor fuel is enormous. Gasoline consumption amounts to roughly 140 billion gallons (17.6 quads @ 126,000 BTU/gallon) per year. Diesel fuel (about 2.7 mmbbl/day out of 4 mmbbl/day of total "distillate" consumption) comes to roughly another 5.8 quads at the pump. If we want to replace just our imported petroleum, we have to replace all of that and more.
I'm wondering how you expect ethanol to do this. You appear to acknowledge that grain ethanol (from corn, wheat, etc.) is a dead end. That's good. What isn't good is your claim that ethanol from cellulose is going to be The Solution. That's only good if it's true, and as far as I can tell it's a long way from that.
Let's forget a few inconvenient details for the moment:
For the moment, let's just look at what we could make from what we've got here in the USA.
The estimated biomass available from sources not currently used is 1.3 billion tons per year. Biomass does not have as much energy per ton as hydrocarbons (around 16 GJ/ton), so the total energy available from this is on the order of 21 EJ or 20 quads. This is only about 45% of the energy the USA obtains from oil each year. But it gets worse.
Conversion from biomass to liquid fuel is lossy. Iogen claims a yield of 330 liters (87 gallons) of ethanol per ton from their enzymatic process. This is slightly under 50% energy efficiency; the 1.3 billion tons would produce 113 billion gallons (~10 quads) of ethanol, with the energy of about 70 billion gallons of gasoline. Conclusion: enzymatic ethanol from unused or waste biomass not only cannot replace petroleum, it can only replace about half of gasoline.
Other processes promise somewhat higher efficiency. Syntec's gasification process is claimed to yield 114 gallons of ethanol per ton (presumably of biomass; the highest theoretical yield would require more energetic inputs, like scrap rubber and plastic... or coal). This is about 60% efficiency, roughly 30% better than Iogen. But another 30% only gets up to replacing 65% of gasoline (and no diesel, no jet fuel, no heating oil, no LPG, and nothing for petrochemicals, coal or natural gas).
And once you've used all your 1.3 billion tons, that's it. You're out of feedstock; you can't get any more out of the inputs without:
It may be even worse than that. If the feedstocks are locked up by long-term contracts, it may be legally impossible to convert even if the consequences of failure are disastrous. A set of entities which have cornered the feedstock market may even scare off the venture capital necessary to create the more-efficient alternatives. I'm sure you understand this very well.
But while that's the end of the line, it's far from the end of the issues.
Climate change is the elephant in the room of all these discussions. As atmospheric CO2 increases, the climate warms. This has knock-on effects all down the line, including a reduction of plant productivity due to heat and water stress.
Recall that 1.3 billion ton number? That's only a historical projection based on what the climate used to be. The steep rise in forest fires in the Western USA may very well indicate that we're not going to be able to harvest that much in the future; a lot of that biomass is going to burn, and hotter, drier conditions mean that it will grow back more slowly if at all.
This applies across the board. Tallgrass crops can burn too (burning is how prairie prevents the incursion of trees). Hay fields burn all too well (see Texas and Oklahoma this year alone). Ripe grain fields can burn, and the productivity of all of these is reduced by hotter weather. We may not have 1.3 billion tons to work with; if we can't control warming, it may be half that.
What's the relevance to your ethanol schemes? It's the fact that we'd still need to get the following from fossil fuels:
All of those would still be pumping CO2 into the atmosphere. Your proposal does involve capturing some carbon from the atmosphere, but it all goes right back; you have nothing to sequester it. If this problem is not to get worse, all atmospheric greenhouse gas (GHG) inputs have to be at least offset by removals.
It's very hard to believe that you don't know all of this already. You've got net worth of over a billion dollars; you have access to the best expert advice in the world, and you have certainly used it before to make your current fortune. Yet the reasons you've stated for supporting ethanol don't match up with the most cursory stab at due dilligence.
It's easy to come up with darker reasons for your position, each worse than the last:
All of these are reasons not to listen to you. The last two are excellent reasons to actively fight you. Maybe you aren't familiar with being on the wrong side of a grassroots battle, but enough people writing letters, volunteering to work for candidates who oppose you, outing your support as astroturf campaigns and voting to stop your plants can throw a monkey wrench into the smoothest business plan.
My advice, offered for nothing: don't go there. Either there is something very important that you don't know, or something equally important that you aren't telling. Straighten this out, and the rest will follow.
I'm sure all of my numbers are good to within 10% or so (corrections accepted). Unless I have screwed something up by at least a factor of three, ethanol can't get us off imported oil (let alone all oil) as long as it depends upon biomass. (Making it from coal is another matter... but mind the environment and don't go there either.) If this problem has a solution, it's not present inside the current model; to see it, you have to step outside the box.
This is my forté.
All variants of your scheme fail because of their common element: they propose, and even demand, reliance on the internal combustion engine. This is essential if we aren't going to replace the vehicle fleet. But why worry about this? The fleet wears out and is replaced regularly as a matter of course; we didn't ban cars without catalytic converters, but they're almost completely gone nonetheless.
The typical light vehicle has a gasoline engine coupled to an automatic transmission using a hydraulic torque converter. The average thermal efficiency of these is abysmal; out of the energy pumped into the tank, perhaps 15% gets to the wheels. The vast majority of these losses are in the engine itself. Heavy-duty diesels are better, getting up to about 45% for medium-speed truck engines.
What this means is that our 17.6 quads/year of gasoline only put about 2.6 quads of energy out to wheels. Our ~40 billion gallons/year of diesel comes to about 5.6 quads, of which perhaps 2.5 gets to wheels. The total actually going to useful work is about 5.1 quads. That's only about 25% of our prospective supply of energy from biomass. This means that the problem IS solvable, in principle. It just can't be solved with ethanol in combustion engines.
Let me make this clear: ethanol is not a solution; it is a niche player at best. It cannot be a mainstay, and any program relying on it to perpetuate the status quo ante is doomed.
Right now you're probably asking, "If ethanol won't work, then what?" While it's logically possible for there to be no solution (e.g. the Halting Problem), you can see that I'm not going to tell you that. Nope, there are better solutions out there. People are putting some of these solutions into practice themselves, because they are tired of waiting for business and government to do it. So I'll list a few for you.
This is the #1 best option for petroleum independence, and eventual fossil independence. The PHEV is a hybrid with a bigger battery pack, a charger and a wall cord. As little as 20 miles of all-electric range would handle the average daily commute and cover 30-40% of all driving; a PHEV60 with 60 miles of all-electric range would cover as much as 74% of all driving. Combined with roughly 1/3 less inherent fuel consumption from hybrid economy, these cars could cut fuel demand by 50-60% with a PHEV20 to a whopping 80+% with a PHEV60.
Note that it's possible to convert a PHEV20 to a PHEV60 just by adding more or updated batteries. Note further that the daily electric demand of these cars, perhaps 15 kWh per day for a PHEV60 driven its full range, is still small enough to carry over standard house wiring at 110 volts for an overnight charge (10 hours). A 220 volt outlet would speed this drastically.
This would convert light-vehicle energy consumption from 17.6 quads of fuel to about 3.5 quads of fuel and perhaps another 2.3 quads of electricity (about 76 GW average). The US consumes about 13.7 quads of electricity (around 4000 billion kWH, ~450 GW average) per year; we'd notice a 17% increase, but if it was scheduled at night, during windy periods, and when generation is otherwise in surplus the grid managers would love it.
The other half of the ground transport problem (that you don't touch) is heavy trucks. These are almost exclusively diesel-powered, accounting for that 5.6 quads of fuel. They're also a tougher nut to crack, because they run longer distances than light vehicles and could not get as much benefit out of conventional batteries.
There are ways to address this, too:
The last three could pretty much eliminate petroleum requirements for long-haul trucking. The DCFC by itself could potentially replace 5.6 quads of diesel with 3.6 quads of carbon. If we harvested 20 quads of biomass and converted it to charcoal at 50% energy efficiency (easily done with low-tech equipment), we'd be able to run the trucks and still have 6.4 quads left over. Even zinc-air fuel cells could manage the job, either chemically (carbon reduction) or with about 6.5 quads of electricity to regenerate the zinc metal from zinc oxide.
This also ignores potential for more-efficient trucks. Wal-Mart is aiming to double the economy of its fleet from 6.5 MPG to 13 MPG. Cutting the problem in half makes it even easier.
Getting the USA completely off fossil fuels, or just imported petroleum, is a huge task. Slashing some of the sub-tasks, like ground transport, down to size is an essential part but not the whole job. For instance, even a full conversion to PHEV60's would leave perhaps 20% of demand for liquid fuel. That's about 28 billion gallons of gasoline equivalent (GGE) per year, or about 135 million metric tons of ethanol. As luck would have it, the process of producing charcoal for DCFC's also produces an off-gas which can be burned, fermented or otherwise processed into product. Roughly 10% of the total biomass (130 million out of 1.3 billion tons) would be carbon in the off-gas. Two companies are pushing processes for production of ethanol from syngas:
Ethanol is 24/46ths carbon by weight, or a hair more than half. If half of the carbon in the off-gas could be converted to ethanol, that would be 130 million tons. That might be a little short of the mark (especially given the difference between short and metric tons), but it's within striking distance of 100%. A plant which uses algae to capture and recycle the unused carbon could boost this figure considerably, creating a surplus for many other uses.
These possibilities are far less developed than ethanol from grain and cellulose, but they actually have the potential to eliminate petroleum dependence. They also have great possibilities for cutting atmospheric GHG's (for instance, the carbon from stationary DCFC's could be sequestered relatively easily... or recycled via algae). Taken together, these possibilities make the three-sided problem of fossil-fuel dependence, oil imports and climate change look manageable.
You're both wealthy and influential. The first thing you should do is dump your positions in ethanol ventures and then state loudly why you did so. Maybe you can help get the "flex-fuel" gas-guzzler loophole closed, just by making it obvious that you changed your mind and why.
You might also do one or several of the following:
In my less than humble opinion, the powers-that-be are promoting ethanol because it serves up subsidies to various interests while not threatening the status quo (oil companies). If you can make an end-run around those interests, you could improve the environment, the economy and the prospects of the average American while making a huge pile of money. Isn't that better than just being a shill for GM, the corn farmers and ADM?
Here's to your change of heart.
Update: "Petajoules" corrected to "exajoules".
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:
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.
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