Sustainable Design

One of my key design goals is to build this car as sustainably as possible. One way to build a sustainable car is to use a Cradle-to-Cradle design methodology. If I ever decided to commercialize this design, I’d want to go through the full C2C certification process, but for now, I’m just following the core principles. Cradel-to-Cradel design involves making the entire product’s lifecycle sustainable. The product should be build out of the most sustainable materials available. Both the manufacturing process and the operation of the product should create no waste, pollution or negative human health effects. And at the end-of-life, the product should be completely recycled without producing any waste or pollution or it should be “upcycled” into a higher-value product. In order to achieve this level of lifecycle sustainability, material selection is key.

 

Sustainable Materials

Materials should be:

• Infinitely recyclable – without any degradation – no “down-cycling”
• Reusable – Rather than recycling components, its’ even better to design them to be “upcycled” to a higher-value product after the useful life of the product runs out

Many common car materials do not fit these design criteria. Some common materials in cars:

• Steel – Must be painted or it will corrode over time
• Paint – Causes air and water pollution during its application and is toxic to the environment at end-of-life
• Plastics and Adhesives – the average car has 150 kilograms of plastic in it – plastics are used in the bumpers, seat upholstery, dashboard, interior trim, exterior trim, and numerous mechanical and electrical components. The vast majority of the plastic in cars causes pollution during its manufacturing, and is not reusable or recyclable.

Some materials that might be considered “sustainable”:

• Aluminum – aluminum is infinitely recyclable without any degradation. It never needs to be “downcycled.” Aluminum is also extremely resistant to corrosion, as aluminum oxide produces a thin protective layer, leading to a dull finish but production against further corrosion.
• Stainless steel – stainless steel is infinitely recyclable and extremely resistant to corrosion.
• Certified wood – wood is renewable and can be grown sustainably.
• Bioplastics – Instead of being made from oil, bioplastics are made from plant starch. Parts can be 3D printed from bioplastics, eliminating manufacturing waste.
• Soy Foam – As an alternative to petroleum-based polyurethane foam rubber used in seat cushions, soy-based foam looks promising, but may not be totally sustainable.
• Cork – Natural cork is another sustainable alternative to polyurethane foam.
• Natural Latex Rubber – An alternative to  petroleum-based polyurethane foam rubber is natural latex rubber, which comes from the rubber tree. Because it can be sustainably-harvested, this product may be preferable to soy foam.
• Renewable Fabrics – Natural fabrics made of sustainably-grown bamboo, hemp, cotton, linen, or wool can be good alternatives to petroleum-based fabrics like polyester, nylon or vinyl. However, in order to meet FMVSS 302 safety standards, these materials must be coated with a fire retardant chemical such as PBDE, which besides being unsustainable, has some pretty nasty health effects.
• Leather – concerns about animal welfare aside, leather can be produced in ways that are more sustainable than synthetic fabrics.

 

Non-Sustainable Materials I Need to Use

So far I have identified a number of non-sustainable materials in parts I have selected that I have not yet found a sustainable alternative for. I hope to do additional research to find alternatives to these.

• Batteries – The batteries will be the largest component of the car by mass. They are typically constructed out of lithium, plastic (for the container), graphite (for the negative electrode), organic carbonates (for the electrolyte) and metal oxides (for the positive electrode). The lithium iron phosphate battery (LiFePO4) I’ve chosen uses lithium iron phosphate as the cathode.
• Wheel Bearing Grease – found sustainable “food grade” grease alternatives here.
• Teflon Rod End Liners – Teflon is polytetrafluoroethylene (PTFE), which is produced from tetrafluoroethylene (TFE), which is produced from chloroform, which is produced from methane (which is natural gas) and chlorine (which comes from salt). While it is technically possible to create plant-based PTFE, I haven’t been able to find any, let alone find rod ends with sustainable high compression strength PTFE liners. On the other hand, these liners only weigh a few grams, so they’re not a high priority for finding sustainable alternatives.
• Motor Coolant – sustainable motor coolant here.
• Plastic Wiring Connectors –
• Epoxy Wiring Sealant – MasterBond makes “food grade” epoxy sealants.

 

 

Sustainable Manufacturing