In this episode of our ‘Sustainability in the Air’ podcast, Nathan Millecam, President & CEO of Electric Power Systems (EP Systems), speaks with SimpliFlying CEO Shashank Nigam about designing the perfect battery to power electric aircraft.
Millecam got into lithium batteries while working at Honeywell. As part of Honeywell’s leadership rotational programme, Millecam was program manager of a project to create an independent power system on a Boeing 787 Dreamliner. Through the project, he met Randy Dunn, the Co-Founder of EP Systems. In 2016, the two started EP Systems with a vision to power a greener future via electric power systems.
Here are the key highlights of the conversation:
How the power team began (3:06)
Using lithium-ion batteries in aviation (6:49)
How hard is it to certify an air-worthy battery? (9:11)
The cost-effectiveness of batteries (14:42)
The importance of power density vs energy density (20:11)
How does EP Systems choose sustainable energy sources? (27:09)
Rapid Fire! (36:18)
Keep reading for a quick overview of the episode.
Why battery technology matters to airlines
Millecam highlights the importance of battery technology in aviation’s inevitable sustainable transformation, in which batteries will become the new fuel source in electric and hybrid-electric aircraft.
However, the challenge is not just about making aviation sustainable, but also making it economically viable. Millecam argues that there’s a risk of inflating travel costs in the quest for sustainability, which isn’t ideal for society. EP Systems is working to alleviate these concerns while ushering in a green future.
Towards greener skies: Electric aircraft are 2.1 to 3.2 times more efficient to operate than their fossil-fueled counterparts. The crunch is that flying an aircraft on electric power requires battery technology that pushes the limit of what is currently on the market. EP Systems is tackling this problem with a vision to “usher in the next stage of electric aviation”. Since 2016, the company has designed over fifty different aerospace battery propulsion systems, most recently the EPiC model.
An economic choice: Millecam explains that one of the biggest costs for jet planes now is the frequent and time-consuming process of engine overhaul. An aircraft engine typically needs to be replaced every 2,000 hours. “Imagine that every other year you had to buy an entire new powertrain for your automobile,” he says. On top of this, replacing an engine can take four to six weeks, which wastes valuable flight time. Jet engines are also expensive and can cost hundreds of thousands of dollars plus additional thousands for engine removal.
Flying electric eliminates these frequent overhaul costs. For example, according to hybrid-electric plane startup Ampaire – which uses EP Systems battery packs – an electric aircraft could have a 90% reduction in fuel costs and a 50% cut in maintenance costs compared to a conventional aircraft.
Constant innovation: Batteries are powering some of the most exciting new innovations: Ampaire’s pioneering Eco Caravan flight took to the skies in November 2022. Boasting an Amp H570 plug-in hybrid powertrain, the nine-seater Eco Caravan claims to be the lowest-emission aircraft of its kind. The plane is an upgrade of the Cessna Grand Caravan, with a new design that reduces carbon emissions by 70% and operational costs by 40%.
5 essential components of an aircraft battery
1. Setting the highest bar for safety
According to Millecam, production and certification for batteries pose a bigger challenge than the design.
Safety standards are much higher for aircraft than other transport industries. In addition to this, safety regulations differ across different regions, Millecam explains. Along with FAA certification, EP Systems’ batteries must comply with regulations in Europe, Japan, and China.
“We have to rise to those standards while rising with the production rates,” says Millecam.
He also explains that a prevalent issue in batteries is “thermal runaway” or overheating, which can lead to them catching fire or exploding. In aviation, it’s crucial to manage this to ensure safety. While containing the issue, it’s also vital to maintain power to the aircraft’s motors for a safe landing. “The energy density of the battery pack is crucial in aviation, and this is our speciality,” he emphasises.
2. An adaptable design
Their EPiC propulsion battery modules are uniquely adaptable for use on different types of aircraft, such as Ampaire’s hybrid aircraft or REGENT’s electric sea gliders. Millecam points out the complexities of battery design for aviation, particularly the differences between those meant for electric and hybrid-electric applications.
A cornerstone of EP Systems’ innovative approach is the aspiration to create a versatile battery module. This universal module can be utilised across various applications, from hybrid systems to purely electric ones, and for both power and energy purposes.
Millecam explains that though it might seem like a straightforward idea, the task is immensely intricate. Typically, batteries are designed specifically for individual applications, ensuring optimal performance and efficiency.
“Batteries want to be customised,” Millecam says, and a customised model also leads to quicker certification. However, EP Systems is striving to break this norm.
By introducing a standardised battery, they aim to capitalise on economies of scale, benefiting the whole industry. Such standardisation can potentially lower costs and enhance production efficiency. Millecam argues that for society to move swiftly towards more sustainable technologies, they need to be not just environmentally beneficial, but also economically compelling.
“We’re big believers in this sustainable space. We know we have to make advancements as a society. Our belief is that it will happen faster if we give economic arguments to the market to say this is a better technology than what you have today. It’s better than your thermal engine.”
3. Energy density at the pack level
Designing batteries at the scale needed to fly an aircraft comes with new technological complexities.
When we talk about batteries, especially for planes, one of the big questions is: how much power can be packed into a small space, and for how long? This is known as “energy density”. In aviation, batteries must be both energy-dense and perform safely at the pack level.
“Energy density at the pack level is everything in aviation,” Millecam says. The challenge of designing such big battery packs is that thousands of cells need to be combined at a high voltage, and managed in unique environments.
For example, monitoring temperature is vital to avoiding thermal runaway – the batteries catching on fire in flight. The EPiC battery module is designed to monitor conditions such as cell voltage and temperature, “and enacts passive balancing to ensure that string voltage remains balanced and optimised”.
4. Recharging speed
Unlike cars that can be recharged leisurely overnight, the aviation industry faces a unique constraint. Aircraft, particularly commercial ones, need to be back in the air as swiftly as possible to remain profitable. This means their batteries need to recharge at a significantly faster rate than those in cars. The longer an aircraft remains on the ground for recharging, the more potential revenue is lost.
Millecam highlights the technological advancements EP Systems has made in this space. They have developed a battery that can be charged rapidly without undergoing the usual degradation in life cycle that most batteries face with quick charging.
In essence, they’ve cracked the code on fast-charging without sacrificing battery longevity. He further explains that the company’s goal is to achieve a turnaround time of about 20 minutes for a battery that’s 80% discharged.
Another crucial aspect of aviation batteries is how many times they can be charged and discharged, known as ‘cycle life’. A battery that doesn’t last many cycles isn’t practical for frequent flying. Millecam says the exciting news is that major battery producers are starting to focus on aviation, indicating a maturity in the technology that’s been developing for a while.
5. Sourcing the right materials
EP System makes their batteries from lithium – a highly power-dense material. Lithium batteries have traditionally been used in smaller flight components, such as in an APU (Auxiliary Power Unit) on aircraft to start engines. Lithium batteries are also the primary power source for electric automobiles.
However, over the past decade, significant advancements in power density technology have made lithium a competitive option for aircraft propulsion, Millecam explains. EP Systems’ experience designing batteries, especially for NASA’s X-57 all-electric aircraft, helped set much of the foundation for their continuing technological evolution.
That said, relying on lithium comes with concern about sustainable sourcing. An estimated 2.2 million tonnes of water is needed to produce just one tonne of lithium. Water supply conflicts are already rising in South American communities in areas of lithium extraction.
Rather than investing in alternate sources, EP Systems’ approach is to “build domestic sources, expand the supply chain and control it.” Millecam highlights the potential investment opportunities in Europe and the US for independent lithium supply, that can help overcome the issue.
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‘Sustainability in the Air’ is the world’s leading podcast dedicated to sustainable aviation. Through in-depth conversations with top aviation leaders, we break through the clutter and provide a clear roadmap for a net-zero future.
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