Over the past few years I’ve been assessing the decarbonization of aviation, in large part because it’s a hard target of high economic merit, and to a certain degree because there is so much overhyped nonsense in the space. Tens of billions of dollars of venture capital and retail investor money has been funneled through SPACs into electric vertical takeoff (EVTOL) and landing aircraft and urban air mobility (UAM) schemes that claim to be electrifying aviation, as an obvious example.
That’s not going to happen for a couple of decades, and to nowhere near the scale imagined by even the most conservative of the startups in the space. What is going to happen is slow electrification, including hybrid drive systems, of the bottom end of the fixed wing conventional takeoff and landing (CTOL/ECTOL) market. What is going to happen is the return of regional air mobility (RAM) that activates the thousands of poorly utilized smaller airports with electric, increasingly autonomous and digitally air traffic controlled aircraft, something I lay out in my maturation projection through 2040 for the technologies and regulatory approvals. Companies like XWing, whose product lead Kevin Antcliff, formerly of NASA, I’ve spoken with several times, are taking lead on autonomy, as an example.
I sit on the Advisory Board of ELECTRON Aviation, which is building a 4-passenger, single-pilot plane with a range sufficient to get from the UK to the Netherlands as an air taxi, or carry 500 kg of freight between airports. Heart Aerospace, whose founder and CEO Anders Forslund I spoke with a year ago, is currently building a 30-passenger hybrid passenger plane, having realized that its 19-passenger fully electric model wouldn’t hit the right business sweet spot. Eviation just flew its 9-passenger, fully electric Alice plane, and orders have passed $2 billion. Another stealth business I’m working with is building another small ECTOL for a specific market that has thousands of smaller planes in operation today.
There are thousands of 50-96 passenger turboprop planes flying scheduled routes which are aging out right now. The average age of the De Havilland Dash 8s operating globally is 24.8 years, and with the average operational hours of just under 1,600 per year, that’s bumping up against the very expensive 40,000 hour airframe inspection requirement. Air Canada’s current small fleet is only an average of 10 years old, but it has retired a lot of Dash 8s as well. Those planes aren’t cheap. The propellers alone can run over $100,000, as I found in discussions with another startup which had asked me to join their board. I declined that one, as I have many requests where I don’t see solid decarbonization alignment, the conditions for success for the firm, any path for me to deliver value, or an ability to effectively influence them.
The bottom end of the aviation market, in other words, is big enough for big business models and will be the first to electrify, as I project in my aviation demand curves through 2100.
But this begs the questions, which were put to me in different ways by two different collaborators: how much electricity will be required for electric aviation and how much will it cost?
First, John Hilgers of ClearSkies reached out. His business model is interesting. He’s a long-term airport technology delivery professional, and in the past few years has extended his technology offerings to include solar farms. Under the USA’s FAA Voluntary Airport Low Emissions Program (VALE), airports can get a significant amount of funding to build solar on the must-be-flat verges of their strips or on buildings or over parkades, taking advantage of the land area and providing clean electricity to supplement their core businesses. Over 100 airports in the USA have solar now, and airports globally have solar farms as well, with Edmonton’s international airport having 120 MW and Groningen in the Netherlands having 20 MW, as examples of two airports I have a connection to.
A while ago he asked me if I knew of had done any projections of aviation energy demands compared to solar farm opportunities on airports. It remains on my list to build a model of this, extending my projection model to consider how much electricity could be locally generated for aviation, how much would have to flow into the airport from the grid, and what would be the balance over time. The regulatory regime airports operate under allow them to sell electricity to aircraft operators without becoming a utility, at least in the USA, which is a somewhat surprising advantage.
The supply chain complexities of aviation fueling become remarkably simplified when it is electrons flowing into airplanes instead of Jet A-1. Right now, carriers operating out of multiple airports have contracts with major aviation fuel providers such as BP and Gazprom (luckily, not that many outside of Russia, I found after investigating their deliveries recently), they provide likely volumes per their schedules, then they update them closer to the flight, then they update them the day before and finally the pilot themselves does the final calculation of the specific amount to fill and does an explicit signoff and handoff of the fueling person. That process has been remarkably slow to automate, with the journey somewhat laid out in this Allplane podcast, and accelerated by COVID-19 of course, among other things eliminating the fueling lead visiting the captain in the cockpit with a clipboard. Technologies and approaches discussed in the podcast were leading edge circa 2000, which I know, as I ran development for startups based on them then, which is eons ago in internet years.
But electricity doesn’t require a global supply chain and global contracts. It just requires enough local electrons, something which can be generated across broad but kind of local regions and transmitted and distributed to airports to add to plane batteries. The airport might buy power purchase agreements (PPA) or virtual PPAs for its own reasons, but what’s relevant is how much energy can get into planes in a reasonably quick period of time. Right now power delivery through chargers is scaling up rapidly, and ground freight and water freight charging systems are pushing the envelope quickly, so aviation will not have a problem at smaller scales initially or larger scales later.
Let’s take the example of the Eviation Alice 9-passenger aircraft, as it’s mid-way between the ELECTRON and the initial Heart ES-19. It has a 900 kWh battery, 9-15 cars’ worth, and will fly 250 nautical miles (460 km) with some left over for divert and reserve. Flights in this class are likely an average of 210 nautical miles, and with divert and reserve of perhaps 200 nautical miles, the battery will likely stay in the 40% to 90% most of the time, which is is good for battery life. Let’s assume 30% to 90% fill-up at the airport, or 540 kWh.
For one plane, that’s just not a problem for the average airport. LAX uses about 155,000 MWh annually just for airport purposes, or about 425 MW per day. That means fueling up an Alice once would add about 0.1% of its daily consumption. Helsinki’s smaller airport uses about 54,000 MWh annually, meaning an Alice would suck back about 0.4% of the average day’s electricity. Note that airports typically use natural gas boilers for heating, sometimes with co-generation units for electricity as well, so this is not all of the energy consumed in airport operations, just the electricity. Airports will fully electrify everything soon enough, so the MWh available will increase.
Helsinki is coincidentally a good example, as Stockholm is almost exactly the 210 nautical miles away I suggested. Finnair alone operates three flights on the route a day most days of the week, and a few extra flights on some days, with other airlines providing more options. Note that the Alice can’t replace the Airbus 320 that flies this route with potentially 170 passengers, but let’s round up the flights a bit to fill in the gaps for business travelers to perhaps 20 Alice flights a day with a few planes.
That would bump the electricity requirements up to around 10.8 MWh per day at each airport, or about 2.5% of the airport’s daily consumption.
Adding electric aviation isn’t going to be a drain on an airport’s electricity supply initially, and we’re a long way from displacing the Airbus A321 with fully electric, perhaps 40 years. It’s going to be a bigger percentage for smaller airports, and Helsinki isn’t tiny with 21.8 million passengers annually, but the scale isn’t particularly a problem.
It also puts solar on airports into perspective. For example, Edmonton’s airport (YEG) had 8.2 million annual passengers in 2019, making it about a third of Helsinki’s scale, and has a 120 MW solar farm that will generate in the range of 210 GWh per year according to NREL’s PVWatts calculator, dwarfing the airport’s own requirements. That varies widely through the year of course, with July seeing about 0.9 GWh per day and December seeing about 0.25 GWh per day.
The large majority of the scheduled flights from the airport, 10-16 to each destination every day, are to Calgary (300 km), Vancouver (800 km) and Toronto (2,700 km), all of which I’ve flown multiple times. The runner-ups are a much smaller number per day to warm places, unsurprisingly, followed by occasional flights to other places.
Let’s use the Airbus A321 with 200 seats as a comparison, as modern jets are remarkably efficient. It burns about 4,400 liters of fuel per 1000 km, all else being equal. Modern jet engines run at 55% efficiency — which is astounding, by the way — but only do that at 30,000 feet altitude at optimal cruising speed. Assuming taxiing, takeoff, and landing take an efficiency toll, we’ll assume 50% efficiency of conversion of jet fuel into useful energy.
Jet A has about 34.69 MJ/liter. Like electric cars, electric airplanes are more efficient, with conservative bottom end projections at 85%.
At an average of 14 flights to each destination per day, the average MWh required for the large majority of flights is about 440, or 0.44 GWh. Keen-eyed observers will note that on sunny days in June, it’s probable that all flights out of the airport would easily be powered by the solar array with net electricity flowing to the grid, while in December, it will have to add a few hundred MWh from the grid. As it normally consumes about 50 MWh per day, the connections would have to be increased, but that’s true regardless as it has to deliver the electricity from its solar farm to the grid somehow.
On the year, that’s perhaps 160 GWh, which the same keen-eyed observers will note is less than the 210 GWh the airport’s solar panels will provide. Tack on the likely 18 GWh or so of airport electricity requirements for the year and the airport still has 32 GWh left over. You can run the entire fleet of ground service vehicles with that, and provide all of the airport heating as well, replacing the 4.2 MW of natural gas co-gen plants doing the job today.
Over the year, Edmonton’s solar farm is probably sufficient to power all flights out of Edmonton, the entire airport, ground fleets within the airport, and to be a regional trucking and car fleet refueling center. Not that it would for decades, as in my projection it’s only about 2070 that ranges in large passenger aircraft will get up to transcontinental distances, and SAF biofuels will be doing the heavy lifting at the top end for decades after that as airframes age out.
That’s insufficient, by the way, to power aviation with green hydrogen from the same solar farm. Solar panels to hydrogen electrolysis to vapor elimination to compression to storage to liquification to plane to boil-off to engines would be much lower efficiency, likely a quarter of more direct use of the electricity, and so the panels that are sufficient for all aviation Edmonton currently sees would only fuel perhaps a quarter of it, even if hydrogen aviation were going to be a thing.
But then there’s the next question, which a stealth founder of another firm put to me recently: how much will electricity cost as an aviation fuel? That’s a lot harder to answer, as retail and commercial electricity prices are highly divergent from wholesale prices due to a variety of policy factors. It’s an interesting question as to how it will play out.
For example, Germany has among the lowest wholesale electricity rates in Europe, yet famously among the highest commercial and industrial rates, $300 / MWh and higher recently. This was intentionally done by them as a policy to drive efficiency in energy usage throughout their economy, and when I did the math, amounted to almost exactly the same extra costs as applied to gasoline and diesel (although not Jet A-1). Clearly as grids decarbonize, promoting efficiency of electricity through high prices becomes counter-productive. That suggests about $160 to fill up the Alice in Germany.
The USA, also famously, has virtually no taxation beyond the basics on its fossil fuels, and at least in the area of aviation, isn’t adding carbon pricing or efficiency driving taxes to them. Its average Transportation sector electricity charges were $102.00 per MWh in 2021, so it would cost about $55 to fill up the Alice.
In Canada, industrial rates per MWh vary broadly, from about $45-60 / MWh for very low carbon, legacy hydro electricity in Quebec and BC, to $150 / MWh for very high carbon, more fossil fuel generated electricity in Alberta and Saskatchewan. That’s a range of $24 – $81 for a fill-up for the Alice.
Assuming the 540 KWh for the Alice, and reversing to liters of Jet A instead, we would need about 140 liters to fly the same distance if it were an internal combustion plane, all else being equal, and using a high 40% efficiency factor. At the current average price of Jet A per liter of $0.80, that would come out to a price of around $112. As can be seen, Germany’s $150 would make electrifying aviation unlikely, the USA’s $55 would make it a no brainer, while Canada’s rates vary from good to very good for electric planes. Coincidentally, green California has among the highest electricity rates in the USA, obviously a policy failure, and its $156.30 per MWh would turn into $84 to fill up the Alice, still a deal.
Then you have the interesting world of airports. They will be able to sell the electricity themselves directly to airplane operators without having to establish themselves as a utility, at least in the USA, per Hilgers. And they’ll want to make a profit on the service. They might receive electricity tax breaks, but if not, they will certainly get incentives of various types to build their own big solar plants and at least some storage.
How will the airport price electricity it manufactures itself? Good question.
What can be said is that a lot of the drivers of the price variances for electricity will go away as we move to lots of renewables, broadly connected with HVDC, with a fair amount of storage on the grid. Then the efficiency drivers will be purely economic, not environmental, and as such lower addons in places like Germany are likely. Secondarily, as we get rid of fueling costs, then shortages and variances and price wars will become a much less common thing. Third, as we interconnect more and more grids with HVDC, markets and competition will do their thing to bring costs and prices down. And if we wisely build lots of 125 year+ lifespan pumped hydro storage, then amortizing capital costs will eventually get to zero, so only operational costs will be relevant.
My take is that the world will trend toward a fairly flat situation globally of retail prices of $40-$50 / MWH in 2020 dollars by 2100, but that there will be lots of geographic and temporal price spikes until then. The spreadsheet jockeys who figure out where to refuel, how much, whether to deadhead, and which routes to favor economically won’t be going away — they’ll be doing even more complex models.
But let’s take a look back into the history of aviation fuel pricing. The reason that Europe is only just starting to price carbon on jet fuel, and why other jurisdictions barely tax it, is because aviation is considered an economic development good. As a result, they artificially constrained the price of aviation fuel to accelerate the adoption of it as national and jurisdictional policies. We can certainly argue whether that was a great idea given the outsized role aviation plays in global warming, but that’s a precedent worth considering.
What if airports as a matter of policy were allowed to exclude electricity used to fuel electric airplanes from various taxes and adders? Given the major efficiency and climate advantages of electrification for all industrial and large consumer segments, what if that were true for all industrial and large commercial electricity rates as a matter of policy, as rates on burnable fuels go up and up, either due to carbon pricing or simply more expensive SAF biofuels? How much would that incentivize the shift to electric aviation? I think a lot, and think that national and international aviation policies should be supporting it.
End note: An original version of this article used Shell public website data of 24 million liters of fuel provided at the airport annually, but while Shell is the major provider there are two other fuel providers. Two commenters questioned the orders of magnitude of energy requirements, so I pulled the piece and re-did the math completely from a different angle and arrived well within the same order of magnitude.
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