How can custom mobile mini generators be used to support resilience?

About 10% of Navajos on the reservation live without electricity. In addition, an NPR poll of rural Americans found that more than a quarter of Native Americans have experienced electricity problems and lived off propane lanterns. For Navajos, getting hooked up to the power grid can be life-changing, and at the same time, is challenging for those living in the Navajo Nation, the largest Native American reservation in the U.S.

Even U.S. residents with good access to electricity are at increasing risk from black outs. For example, in August 2020, California experienced rolling blackouts due to a heatwave that caused about 4,400 megawatts of power, which reveals that even for the most innovative state in the U.S., there is still a need for improvement of energy efficiency. Annually, California generates around 200k GWh electricity; if 5% — the typical conversion efficiency of a traditional thermoelectric generator (TEG) — of the waste heat could be recovered, around 10k GWh potential energy could be saved. This would slow fuel consumption, reduce CO2 emissions and save approximately $2.9 million according to the electricity cost.

Song's project aimed to leverage his lab's technology to help Native Americans access electricity for powering flashlights, charging phones, or maintaining jobs and to lay the groundwork for more efficient and resilient energy systems.

Song's project uses additive manufacturing to obtain a unique-structured thermoelectric generator that can significantly improve energy efficiency and provide sustainable energy sources. In detail, his technology innovation is to design and manufacture a thermoelectric generator (TEG) using new materials and creative structures. His team leveraged polymer science and nanoparticle engineering for new materials. Their in-situ polymerization of polyaniline (PANi)/carbon nanotubes (CNTs) exhibited unique nanostructures that can transform the composites’ electrical, thermal, and mechanical properties. The π-π interaction between aniline molecules and CNTs, resulting in stable adsorption of PANi backbones on the CNTs surface, will significantly improve the energy transition efficiency.

The TEG’s flexibility, which is critical for applying the devices to complex surfaces, will be produced with the 3D printing technique, a creative and limber manufacturing approach. The adjustability of 3D printing enables various structures that facilitate energy harvesting. Song's team successfully designed and produced a gill-inspired form with sophisticated dimensional features and fused deposition modeling (FDM). Their preliminary results confirmed the TEG's benefits when the generator is in close contact with curved surfaces, including human skin, vehicle exhaust pipes, industrial hot tubes, hot rocks, or road surfaces in outdoors, proving massive potential in energy sustainability. They also demonstrated the 3D printed generator in devices for collecting close-to-human-body energies to power wearable electronics, such as iPhones. A self-powered health monitoring system based on Song's TEG could benefit people who care about potential diseases and need remote point-of-care services. More importantly, his collaboration with SRP will enhance the upcycling of waste solids and help protect the environment in communities.