Right now, the world is facing a challenge in reducing its carbon emissions. To meet our long-term goals of stabilizing the climate and preventing a 2°C increase in global temperatures, we must do more than just implement renewable energy sources.
We need a profound shift toward decarbonizing our energy usage. This means not only producing electricity without emitting carbon but also using this clean energy for our heating and transportation needs.
We’ve already begun this transition for vehicles like cars and buses. However, there’s a unique problem when it comes to a lightweight mode of transport: airplanes. Batteries, which are crucial for electric power, have limitations due to their relatively low energy density.
In simpler terms, you need a lot of heavy batteries to power an aircraft, which can be a problem because of the added weight and the space they occupy. That’s why many experts believe that biofuels might be a more practical choice for aviation. Nevertheless, some companies are determined to develop electric passenger aircraft.
So, the question is, who is taking a realistic approach? To answer this, an international team has assessed whether battery-powered electric aircraft can become a viable option and when we might see them on the market.
Better batteries
The researchers examined several key questions regarding the feasibility of using batteries for air travel. They considered whether batteries can provide enough energy to make electric aviation possible, whether it’s economically viable, and whether it contributes to our emissions reduction goals.
However, these issues are more complex than they appear. Airplanes don’t just contribute to climate change through carbon emissions; they also create contrails that influence high-altitude clouds, which have their own warming effect. Additionally, the emissions savings from battery-powered aircraft depend on the availability of renewable energy for charging.
In simple terms, the problem’s magnitude is easy to grasp. Currently, the best lithium-ion batteries have an energy density of about 250 watt-hours per kilogram. To enable viable battery-powered airplanes, we would need batteries with at least three times that energy density and possibly as much as eight times (2,000 W-h/kg).
Historically, battery capacity has increased by around three percent annually, meaning it roughly doubles every 25 years. Despite recent progress, even with faster advancements, it’s likely we won’t have the necessary batteries until at least the middle of this century.
(The specific battery chemistry needed to achieve this is also uncertain. Lithium-air and lithium-sulfur designs with higher energy density exist but may not discharge quickly enough for power-demanding takeoffs.)
The researchers focused on modeling an 800 W-h/kg battery, which is considered the minimum requirement for an aircraft the size of a 727. They also explored a more optimistic scenario with a 1,200 W-h/kg technology.
In the less efficient case, batteries would weigh twice as much as fuel, but this is offset by the greater efficiency of electric motors compared to combustion engines. An added benefit is that these batteries can also power onboard systems, simplifying the aircraft’s design.
Will it cut carbon?
Suppose we manage to build electric aircraft. Would they effectively reduce carbon emissions? As things stand, not quite. In fact, given the typical emissions associated with powering the US electrical grid, electric aircraft, including losses during electricity transmission, would produce emissions about 20 percent higher than those from a modern, efficient jet engine.
However, this doesn’t mean electric aircraft would have no climate benefits. Once we account for the extra warming effects of aircraft, electric planes come out ahead by approximately 30 percent.
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Looking into the future adds complexity to the equation. The cost of renewable energy is expected to continue decreasing, making renewables a more significant part of the grid and reducing emissions. Additionally, most aircraft charging is anticipated to occur during daylight hours, which aligns with peak solar energy production.
If future solar energy reduces electricity costs during the day, it could improve the economic viability of electric aircraft. Currently, electric planes make economic sense with fuel prices at about $100 per barrel.
The impact on air travel heavily depends on future advancements in battery capacity. The researchers estimate that an effective range of around 1,100 kilometers would allow electric aircraft to cover 15 percent of total air travel miles and nearly half of all flights.
This would increase global electricity demand by approximately one percent, with most of the impact on industrialized nations. Extending the range to 2,200 kilometers would enable electric aircraft to handle 80 percent of global flight distances.
In summary, this technology appears to be on the cusp of becoming commercially viable and has the potential to reduce the warming caused by air travel. Crucially, these prospects are likely to improve as renewable energy gains a larger share of the energy generation market.
However, the primary bottleneck is battery technology, which currently falls short of the capacities required. While we can’t rule out a groundbreaking advancement in battery chemistry, the current pace of change suggests we’ll have to wait more than 30 years before air travel no longer means the roar of jet engines.
Navigating Electric Aviation Challenges: A Look at Tecnam’s P-Volt and Future Perspectives”
Overview: Tecnam’s P-Volt, a light electric aircraft, faces initial challenges with a limited range of 150 kilometers on a fully charged battery, including a mandatory 30-minute energy reserve. This range may suit short-haul routes in Norway but presents challenges for broader applications.
Expert Perspectives: Lars Enghardt, director of DLR’s Institute of Electrified Aero Engines, expresses skepticism due to current battery limitations, particularly in achieving significantly increased energy density in the near future. He sees niche markets like Norway as potential opportunities but suggests hybrid-electric concepts for longer routes with larger aircraft.
In contrast, Rolls-Royce’s Chief Technology Officer, Grazia Vittadini, is optimistic about electric flights. She emphasizes their seriousness and envisions all-electric aircraft with up to 30 seats operating by 2030. Vittadini sees Norway as a frontrunner in Europe for these advancements.
Key Points:
- Tecnam’s P-Volt faces range limitations initially, primarily suitable for specific short-haul routes in Norway.
- Enghardt is skeptical about near-term advancements in battery energy density, suggesting hybrid-electric concepts for longer routes.
- Rolls-Royce’s Vittadini is optimistic, predicting all-electric aircraft with up to 30 seats by 2030 and highlighting Norway as a leader in Europe.
Outlook: While challenges persist, the aviation industry remains committed to advancing electric flight technology, with varying perspectives on the timeline and feasibility of widespread adoption.