Another Monday Message Board. Post comments on any topic. Civil discussion and no coarse language please. Side discussions and idees fixes to the sandpits, please.
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John Quiggin 
Come fly with me, by The Biofuels
The biofuel industry is bigger than you think. The IEA gives its annual production as 970 mtoe (ref below), a surprising 22% of the tonnage of fossil oil. A photo of a modern biofuel plant in Huelva, the port from which Columbus set sail. It’s part-owned by Spanish oil company Cepsa, hedging its bets.
The growing interest in biofuels for the energy transition comes from two things. One is that functionally they can be made close enough equivalents to current fossil fuels (gasoline, kerosene, diesel oil, natural gas) for replacement to be nearly drop-in. The other is that they tap into and divert the natural steady-state carbon cycle of plants, fungi, animals, and microorganisms, which release CO2 and methane as they die and decay, and fix carbon from the air or water as they grow. Done right, biofuels can be carbon neutral over a reasonably short period of a few years. On paper, they could even be carbon-negative if natural decay emissions of methane were replaced by less potent emissions of CO2, but SFIK nobody has claimed to have achieved the feat.
There is of course plenty of opportunity for cheating, as with the Drax power station in England, converted from coal to wood pellets obtained by shredding 50-year-old mature trees in the US. It is also a bad idea to convert land needed for growing crops to producing energy we can get harmlessly from the sun and wind. Biofuels therefore need to follow rigorous standards of sustainability. There are certification schemes run by the EU and others, but I don’t know enough about them to comment usefully. I will focus instead on an apparent side-issue that I suspect is more important than it looks, fungibility within the sector.
The IEA has given just two pages of its 355-page 2023 World Energy Surveyto “advanced bioenergy”. ( https://iea.blob.core.windows.net/assets/42b23c45-78bc-4482-b0f9-eb826ae2da3d/WorldEnergyOutlook2023.pdf ) They are very strange pages.
First, the IEA limits its scope to “advanced bioenergy”. The non-advanced kind they leave out is a mixture of Third World peasants burning firewood and charcoal for cooking, at great cost to their health, and more recent bioethanol boondoggles, mostly in the US Midwest and Brazil, which use large and wasteful subsidies to divert perfectly edible maize and cane sugar into fuel for gasoline cars. The IEA rightly disapproves of both, but they are facts and winding them down is a significant part of the policy challenge. FWIW, my pet solution to the firewood problem is bottled butane, as delivered every week by truck to half the houses of my neighbours here in Spain. Every village in the world can be reached with bottles by delivery moped or mule. Source the butane biologically. Got a better idea? Fine.
Second, a pretty chart (Figure 3.31) compares three forms of bioenergy, solid, liquid and gas. The respective units are million barrels of oil equivalent per day, exajoules, and billion cubic metres. The authors went to extra trouble to make the chart misleading. The underlying dataset is all in exajoules, very hard to grasp imaginatively but at least consistent. Source here: https://www.iea.org/data-and-statistics/data-product/world-energy-outlook-2023-free-dataset-2 (free login required)
To make it more comprehensible, I extracted the bioenergy data, plus aviation for reasons I’ll come to, and put it in a simple spreadsheet, available here: http://www.jameswimberley.es/Notes/WEO2023_AnnexA_World_selection.xlsx
I added some conversions. I only get one vote here but as the energy transition will consist largely in making everything possible electric, I suggest we might as well use the familiar watts for power and watt-hours for energy. 1 kilowatt is roughly the power of one horse or four Olympic triathletes on the cycling leg. https://pubmed.ncbi.nlm.nih.gov/24235776/
Dividing bioenergy into three streams in this way reproduces the categories of the dying fossil fuel era, with solid coal, liquid oil and gaseous methane, each with their own pathway from well or mine to combustion. The conversion of coal to gas and oil was significant in the past, but not recently. This separation does not hold for biofuels, with multiple and forking pathways, both biological (fermentation with yeast or anaerobic digestion with bacteria) and chemical (adding and removing atoms from carbon chains with catalysts and energy).
A representative solid biomass input is a tree. A commercial plantation or managed forest will generate a large supply of small trees and branches from thinning at 10 or 20 years, too small to be usable for timber. Slender poles were once useful to farmers but not so much today. To a first approximation, a tree consists of two-thirds cellulose and one-third lignin. Cellulose is a linear molecule and readily forms an elastic matrix in plant cell walls. It is easily converted into biomethane – a gas – and bioethanol – a liquid – by bacteria and yeasts. Lignin forms sticky sheets that hold the cellulose in place and confers compressive strength on the cell. It resists attack by microorganisms. Currently, the lignin in our dead tree is extracted as a solid and burnt to provide process heat in pulp mills. However, lignin can be turned into liquid biofuel in a chemical process, and even become feedstock for making enzymes, not an energy use at all. This trans-gender-like flexibility is, I expect, far from unique.
As a thought experiment, consider the rumour that the *Puppeteer trading post at Alpha Centauri offers for sale a universal biorefining machine. Puppeteers are very advanced technologically, and extremely risk-averse. The machine has an input hopper for any kind of organic material, from trees to seaweed to space monsters to pig manure; an additional input port for topping up molecules with hydrogen; an electrical supply cable, rated for 2,000 amps; output ports for solids, gases, and liquids; and a control panel. The machine will transform a given organic input into any thermodynamically feasible set of hydrocarbon outputs, solid, liquid or gaseous.
The AI in the control system will tell the operator what the user’s selection will cost in money and energy. It will also give sound advice on the economic choices, as well as warnings on the technical ones. The advice cannot be turned off, nor muted. The machine is guaranteed for 500 years. Users are STRONGLY advised to RTFM. Unauthorised servicing of the machine is treated as attempted theft of IP and the machine will use all necessary methods to stop it. A footnote in small print states that the lethal blast radius is 500m. Did I say that Puppeteers are risk-averse? This means that they don’t bluff.
The machine is a fantasy. But its abilities (hopefully not the hardline IP policy) will, I suggest, be approached by the global biorefining industry as a whole, within the IEA’s distant horizon of 2050. Biofuels are fungible over time, and it is deeply misleading to treat the supply of just one of the three streams as a real long-term constraint.
For the most part, biofuels are fairly expensive icing on the transition cake. For most purposes, including land transport, industrial process heat, and water and space heating in buildings, it will be cheaper and simpler just to go electric.
There is one big exception: aviation. You can go out today and buy a certified 50-minute electric trainer from Textron, and Vancouver-based based Harbour Air are well into the certification process for a seaplane electric taxi. The important word is “certified”. Aviation regulators are paid to be fussy and will be especially so for a radically new propulsion technology. There are other serious companies (Heart, Eviation) planning to market 30-seater battery-electric or hybrid commuter planes in a few years’ time. They will have with an electric range of 200 km or so using current leading-edge batteries, which are themselves continuing to improve. Once the batteries are good enough, the unbeatably low fuel and maintenance costs will drive rapid adoption, one use case at a time. The open question is how much of the short-haul market will go electric by a given date.
At all events, there is no alternative in sight to liquid hydrocarbon fuels for long-haul civil flights and military aviation. These should therefore get the first claim on biofuels. Will there be enough? The different IEA scenarios suggest that there won’t be if liquid biofuels are a silo.
Current:
– 2022 aviation demand 251 mt kerosene, liquid biofuels 102 mtoe, 41%
(peak, stated policies scenario)
– 2050 aviation demand 501 mt kerosene, liquid biofuels 186 mtoe, 38%
Trough, net zero 2050 scenario:
– 2050 aviation demand 66 mt kerosene, liquid biofuels 255 mtoe, 386%
However, if I’m right that biofuels are fungible over time, there will be far more than enough supply under any scenario: 2022 current 970 mtoe, 2035 stated policies 1,388 mtoe, 2050 stated policies 1,734 mtoe.
Net zero flight is feasible. IMHO a reasonable amount of travel in unredeemed commercial (not private) planes is ethically OK provided you (a) offset your flight emissions, (b) agitate for policies that will bring about net zero aviation using batteries and biofuels, and possibly (c) agitate against policies that will waste limited biofuel on land transportation.
Note 1
It is safe to ignore synthetic e-fuels from green hydrogen. These don’t exist today in commercial quantities. Biofuels are already a real billion-tonne capitalist industry. Planes have flown the Atlantic using them, and US Navy fighters flown from aircraft carriers. https://corporate.virginatlantic.com/gb/en/media/press-releases/worlds-first-sustainable-aviation-fuel-flight.html Synfuels, if anyone were foolish enough to make them at scale, would cost over twice as much, and that’s before the expensive switch to green hydrogen from the dirty kind.
https://www.climateworks.org/wp-content/uploads/2021/11/GINA-Low-carbon-fuels.pdf, pages 4, 6
Note 2
What about shipping? Two things are sure to happen. Short-haul (ferries, tugs coasters, cruise ships, inland waterway barges) will go electric. A Chinese shipowner has launched a battery-electric 700-container ship on the Yangtze. That leaves long-haul oceanic shipping where batteries can’t provide enough range. The second hard prediction is that the business will contract, as the oil and gas tankers are scrapped, the iron ore carriers switch to transporting iron pellets from DRI plants near the mines, saving 40% of the cargo weight, and carbon border taxes cut into the hypertrade that comes from unpriced externalities.
It is technically possible to run the surviving ships on ammonia, though it’s nasty stuff and likely to be expensive if made from green hydrogen. The shipowners will much prefer biodiesel, with negligible new investment costs in ships and ports. At first sight there will be enough biofuel for this too.
* Puppeteers are an intelligent alien species in SF writer Larry Niven’s Known Space universe. https://en.wikipedia.org/wiki/Pierson%27s_Puppeteers. The spiky biorefinery is not his idea but my modest contribution to the timeline.
Hurrah, hurrah!! Thank you for the good news (if we manage not to blow each other and the planet up, that is … which, so far, we haven’t done … )
Just great, Macron, who did not bother to put any effort into ammunition production or supply any weapons that cost real money or lower his own armies capacities temporarily now cannot exclude to send Nato soldiers into Ukraine. What else can you ask for than verbal hawkishness to distract from your own penny-pinching when dealing with a nuclear armed Nation. Ah right, we also got Trump, who wants Russia to win.