We aim to tackle two issues: provide renewable energy and keep the sewerage clean. To achieve this, we divided it into two main components: a power generator and a fishnet-like mechanism that acts as the cleaner.

The product is specifically designed for sewers on street corners in Ho Chi Minh City. The net mechanism will be installed at the front, completely covering the sewer mouth, along with a rotating component. The net would rotate periodically in order to remove any litter present, with a litter box on top, concentrating them into one area for ease of collection. A water turbine is installed inside a sewer pipe below and harnesses the kinetic energy from water flow, and transfers it through a series of gears to turn the generator, producing electricity. The power produced will be allocated among two paths: charging the batteries and powering the trash-removing mechanism, both monitored by an Arduino motherboard. The batteries will serve as a backup resolution for times when the mechanism requires a higher amount of energy or when the system goes into hibernation during the dry season.

Diving deeper, the unpredictable nature of rains in Vietnam forces us to be innovative and come up with an adaptive design that would work in various water flows. Firstly, we conducted on-field investigations and learned from some city-planning executives about the structure of the sewerage. The most common pipe diameter is 300mm, with a minimum flow velocity of around 0.8m/s, and can get up to 2m/s during the rainy season. Through calculations, accounting for the regulated filling ratio up to 0.6 of the pipe diameter, there are as many as 40W of power readily available from usual sewerage activity. This provides a steady energy flow at all times, ensuring a consistent power output. However, considering a few extreme flooding cases happen during the year, preventing system overload is necessary. Therefore, we arrived at a solution similar to that in our day-to-day motorbikes – a gear shifter. This idea utilises the principle of torques and gear ratios to ensure a steady energy input to the generator, and also to prevent overload in extreme floods. After extensive research, we saw the potential of this solution, especially through a research that quoted "The power output increased by nearly five times".

Furthermore, many newspapers have revealed the health risks that public cleaners have to face when they clean the sewerage, spending 4-6 hours each day cleaning matters ranging from exposed used needles to possible diseases from the decomposing dead animals. In addition, there have been many occasions where extreme floods were caused due to trash blocking the sewers, affecting the whole district and posing death risks because of exposed power lines. Therefore, considering the 80,000 sewers around the city that require thousands of hours of intensive labor to maintain, the application of the product will not just provide renewable energy to the community, but also provide a new solution in keeping the sewerage clean without human labor, ensuring people’s health and well-being. This is a critical point, as blockages happen in many other developing countries such as India, Bangladesh or Myanmar, and they all share a common point of risking public cleaners’ health to keep the sewerage clean. To humankind as a whole, ensuring people’s health and safety is the goal, to which we think that our product is able to achieve that.

However, we are also mindful of reverse-engineering and the competitiveness of markets both domestically and internationally. Under the Vietnamese government copyright law, our product design will be protected for up to 20 years, which would allow us to develop our market share safely in the domestic markets. Furthermore, to prevent foreign competitors from reverse-engineering and access to our product, we would be involved closely with the Ministry of Natural Resources and Environment, and the Ministry of Construction to receive a higher level of protection due to involvement in governmental programs.