Low carbon PCBs: a wake up call

In our mission to produce the world’s cleanest motorcycle by 2025, one of the smallest components is proving to be one of the biggest challenges. Could you help?

The Cleanest Dirt Bike Ever is a joint venture between Vattenfall and CAKE. We’re rethinking every step of the supply chain for the CAKE Kalk OR bike – tracking its emissions all the way to the source and finding ways to remove them.

Since we conducted our life cycle assessment (LCA), we’ve been working on the key materials that go into the CAKE Kalk OR, evaluating both traditional and non-traditional materials as well as looking at manufacturing methods to reduce the production emissions of the bike. We’ve encountered some significant challenges, for example unavailability of certain manufacturing processes like forging and seamless extrusion, leading us to re-think the design of the bike itself. Right now, we’re working together with our partners to overcome these issues.

Despite this, we have a good grip on some of the key materials such as aluminium, steel and plastic which represent 41% of the bike’s total emissions. However there’s one material group that’s proving to be a bigger hurdle than we anticipated – electronics. The electronics include all cables and printed circuit boards (PCBs). A PCB is a medium to connect components in a circuit, typically a non-conductive material with conductive lines printed or etched.

How much do PCBs emit?

The Kalk OR has only three parts containing PCBs, representing just 0.7% of the bike’s weight. But PCBs have a heavy carbon footprint. From the LCA, we know that PCBs account for 10.5 % of the bike’s total emissions.

An assembled PCB includes the board and all electronics components mounted on it. Depending on its design and application, a PCB’s carbon footprint can vary significantly.

“The PCB in the Kalk OR’s dashboard has a carbon footprint of 24 kg CO2e while the PCB in the controller accounts for 46 kg CO2e. The difference is due to a larger board surface area and more electronic components.“

- Avinash Kumar, LCA Specialist at CAKE

Figure 1. Emissions flow diagram of PCB

The PCB value chain

Diving deeper, we can see that the board itself accounts for less than 8% of the PCB’s total carbon footprint. (See figure 1.) The source of electricity in manufacturing accounts for 62% of the board’s emissions, with the remainder coming from the materials used – including resin, glass fibre and copper – and other chemicals. (See figure 2.) So, alternative materials combined with clean energy could result in significant emission reductions for the board.

Figure 2. Share of emission from the board in a PCB.

Far more critical is the integrated circuit (IC), accounting for 89% of the PCB’s total carbon footprint. The source of the IC’s emissions is split almost equally between electricity, gold and silicon wafer. (See figure 3.) Here, we need to focus decarbonisation efforts not just on renewable energy but on the gold mining and silicon production industries.

Figure 3. Share of emission from the integrated circuit in a PCB.

The total global production of silicon in 2022 was an estimated 8.8 million metric tons, of which China was responsible for 6 million metric tons, meaning the global supply chain of electronics such as ICs, capacitors, resistors and transistors is heavily reliant on China. The supply of gold depends on mines located in more diverse locations. But in both cases, for electronic components which rely on these materials, supply chains are complex and the decarbonisation actions needed are significant.

What does this mean for the Cleanest Dirt Bike Ever?

These factors mean that right now there’s a shortage of low carbon PCBs. In the medium term, we believe that increased consumer demand will help to drive the investment needed upstream in the PCB value chain such as gold mining and silicon production. But with a deadline of 2025 to produce the Cleanest Dirt Bike Ever, we also need to explore ways to reduce the bike’s PCB emissions in the short term.

So the Cleanest Dirt Bike Ever project is looking for companies operating in these sectors who are actively working to decarbonise supply chains. We’d like to explore the decarbonisation pathways and unravel the complex challenges together. The electronics industry needs to accelerate its journey towards decarbonisation and we’d love to collaborate to make a tangible impact.

Reach out to us at cdbe@ridecake.com if you’re working in this field and looking to speed up your decarbonisation journey.

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