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Cake day: March 22nd, 2026

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  • Sustainable aviation fuel doesn’t need to come from biomass feedstocks (even if those are by far the most popular). There are pathways for purely synthetic hydrocarbon production, but most sustainable fuel comes from organic sources (crops, organic waste, or fossil fuel sources). Even some of the synthetic methods tend to still get stuff like syngas from processing coal or natural gas.

    Still, developing the processes and the scale to bring prices down is important, and can be built upon with an eye towards replacing the biofuel feedstocks with CO or CO2 feedstocks, and can still spur on demand for more renewable energy (without the risk of the return on investment collapsing).


  • He said that governments had, through ICAO, targeted a 5% emission reduction by 2030 by using SAF. However, he cautioned: “To be blunt, there is no path to meet that outcome.”

    The 2050 goal seems far enough away that success or failure can be hand waved away, from the perspective of the goals being announced in 2021. But they set a goal for 5% by 2030, and it is concerning that we haven’t seen sufficient advancement in scaling up production of sustainable aviation fuel.

    I’m most interested in fuel production being an energy sink for excess solar power. If we can set up a system where we overbuild solar electricity capacity far more than what we’d need on any given day, but divert some of it to storage (for use at night) and use some of it to produce chemical fuels with stored chemical energy, a large enough operation might be able to support demand for solar panels without jeopardizing the grid with too much waste electricity (and the economic side effects of producing something fleeting that nobody wants to pay for in that moment).



  • that 20000-30000 premium over ICEs

    What currency are you using for this comparison? Definitely not USD.

    A Tesla Model 3 runs for about $40k. A Camry runs for about $35k. Or if we want to go down market a Nissan Leaf is about $30k and probably comparable to a $25k Sentra.

    Similar trim levels of vehicles offered as both EV and gasoline powered show minimal difference. Compare the Ford F-150 Lariat in both the gasoline ($75k) and the EV versions ($79k). Or the new Lexus ES, where the EV ($49k) is actually cheaper than the hybrid ($51k).

    And if you go into the used market, EVs are starting to hit that market in real numbers, too. Plenty of options for under $20,000, and a handful of options for under $10,000.

    Cars are expensive. EVs generally are close to that already expensive price.


  • capital costs for the wire and components all along the way is massive

    That’s true of pipelines, too. It’s just that the sheer quantity of energy contained in those chemical bonds of chemical fuel is massive, so amortizing the up-front capital costs across how much energy can actually move through that pipe or cable in its lifetime tends to favor a pipe full of chemical energy, on a per kWh (or per joule) basis.



  • Yes, the numbers change for shorter distances. There’s some loss in loading up a fuel tank and driving it to the station. But again, the high energy storage capacity of chemical energy still makes a huge difference.

    If a loaded semi gets 8 miles per gallon of diesel, then moving a tanker full of 10,000 gallons of gasoline 200 mile (320 km) s will burn 25 gallons of diesel in order to transport 10,000 gallons of gasoline. Even with less efficient trucks (let’s say 6 mpg for 33.3 gallons of diesel burned), it’s still pretty efficient in terms of “losses,” of about one third of one percent of the original volume of fuel consumed. Of course, diesel is more energy dense than gasoline, especially gasoline mixed with ethanol, so the efficiency might drop to 99.5% instead of 99.7%, but we’re still talking about a pretty fundamentally efficient operation.

    The real efficiency gains of electricity over fossil fuel (or any chemical fuel) comes from the more efficient motors. An electric car that goes 3 miles (5 km) per kwh is the equivalent of going 100 miles per gallon (42 km/L) of gasoline. A heat pump that has 300% efficiency only needs to transmit 1/3 as much electrical energy as would have been necessary for bringing fuel to a combustion-based heater.

    So if you start breaking it down by actual use case, you might be able to make some gains back to mitigate the higher cost of transporting electricity across large distances. But it still remains that all the other methods are very efficient, too.


  • Pipelines are absurdly efficient because moving liquid or gas through a pipe is absurdly efficient per kilogram per kilometer, and the energy density of fossil fuels is absurdly high.

    A Tesla supercharger v4 can deliver 500 kW of power. BYD has launched chargers that can deliver 1000 kW (aka 1 MW) to a single car. Naturally, each kW of power is capable of delivering 1 kWh per hour.

    What is the equivalent flow rate in gasoline? 1 gallon of gasoline contains the equivalent of 33.4 kWh (1 L contains 9 kWh). So 1000 kW would be the equivalent of 30 gallons per hour (110 L/hr), or 0.5 gallons (1.85 L) per minute. That’s 5% of the rate of a typical gasoline pump in the United States.

    Plus exposed high voltage wires need to be maintained in weather and around vegetation, so they have high operating costs. Then there’s higher capital costs of making sure that there are transformers and safety equipment that step the voltage up and down and sync with the rest of the grid.

    In the end, it really is that power lines aren’t capable of carrying nearly as much energy as the chemical fuels that flow through a pipe, so on a per joule/kwh basis, there’s less economy of scale from power lines.



  • It sounds like you have no idea the magnitudes involved, or the timelines. You’re talking about something that took place over a period of 400 million years and whose effects (the presence of oxygen in our atmosphere and our oceans) remain. There’s no chance that geoengineering would change the oxygen levels to anything we can’t handle, and if it starts to head down that direction we can easily handle it (just stop the processes that would sequester carbon).

    It’s like being worried that your air conditioning is going to freeze your pipes in the house, in the middle of summer.