Scientists from Colombia’s CESMAG University and the National Open and Distance University have proposed a way to convert river transport in remote areas of the country to electric boats powered by renewable energy. To achieve that, they have developed a model that calculates the power consumption of these boats and determines the required capacity of their charging system.
In many areas along Colombia’s Pacific coast, rivers effectively serve as roads. They carry people, including schoolchildren, as well as agricultural produce and fish. However, river transportation depends on gasoline engines almost entirely. For remote communities, this means high fuel costs, fuel delivery issues and environmental pollution. In some locations, fuel can be several times more expensive than in large cities.
The researchers have proposed using electric engines instead of gasoline engines and generating electricity to charge them locally via a small and self-contained power system. A microgrid of this type could include solar panels, batteries and a hydrokinetic turbine to generate electricity using the energy of the river’s current.
To gain an understanding of how much energy would be required to operate this transport system, the scientists first reviewed the existing boat routes on the Mira River. Using GPS, they recorded travel speeds and trip lengths to build a mathematical model of power consumption. They found that waterborne transport is highly nonlinear: a small increase in speed leads to a sharp increase in power consumption. For instance, a speed increase of about 50% may require a nearly fourfold increase in engine power.
Based on these data, the scientists calculated the power consumption for daily routes exceeding 30 km in total length. For these routes, it would be sufficient to operate two electric boats: one with a small capacity of about 1.1 kilowatts for short crossings and another one with a capacity of some 4 kilowatts for longer trips. In total, they require about 5.7 kWh of electricity per day, roughly the same amount a small house consumes in a day.
The researchers then modeled two energy system options for the charging station. The first option relies solely on solar panels and batteries. The second option is a hybrid one: it combines solar power with a turbine installed in the river. Calculations showed that a fully solar system is cheaper, but a hybrid system is more reliable, as it can generate energy even at night or in cloudy weather thanks to the constant river current.
In addition, the scientists compared the operation of electric boats with conventional gasoline-powered boats. The results demonstrated that a standard boat with an engine producing about 20 horsepower burns hundreds of gallons of gasoline annually and emits more than three tons of carbon dioxide into the atmosphere. Electric boats, especially those using renewable energy, produce virtually no such emissions. Moreover, they are significantly cheaper to operate: electricity costs can be orders of magnitude lower than fuel costs.
Economic calculations show that the initial investment in electric boats pays off relatively quickly. The payback period is less than two years for a small model and about five years for a more powerful one. On top of that, the more powerful electric boat can deliver speeds and travel times comparable to conventional gasoline-powered vessels.
