The Thermal Load of Urban Roads
The asphalt surface of a road absorbs 95% of incident solar radiation, heating up to 60°C (140°F) in summer. This thermal accumulation is released into the surrounding air, creating a temperature gradient that forces urban cooling systems to consume additional energy. The MIT has quantified that a 10% increase in tree cover in urban neighborhoods reduces the average surface temperature by 2.3°C (4.1°F), but this green resource is not evenly distributed: in examined cities, high-income areas have up to 40 times more trees than low-income areas.
The energy transition cannot ignore this physical asymmetry. While 121 electric buses powered by renewable sources operate in Senegal, their effectiveness depends on the electrical system’s ability to manage cyclical loads. Each bus requires an average power of 300 kW for charging, with peaks of 600 kW during rapid charging operations. This implies an increase of 36 MW of installed power, which must be balanced with the existing network capacity.
The Performance of Charging Networks
The distribution of energy for electric buses requires a charging density of 15 kW/m² for charging facilities. In urban contexts, this density is limited by the availability of space and the capacity of the distribution system. In Senegal, the existing electrical infrastructure has a maximum capacity of 450 MW, with an average power of 320 MW. The addition of 36 MW for electric buses reduces the network’s safety margin to 12%, increasing the risk of overload during peak demand.
Advanced storage technology, such as lithium-ion battery systems, offers a partial solution. A 500 kWh battery can store the energy needed for 10 buses, but requires a 1,200 m² facility and an initial investment of €1.2 million. This model cannot be replicated on a large scale without a restructuring of the existing electrical grid, which in Senegal would require an additional investment of €180 million.
The Bottleneck of the Transition
The bottleneck is not technological, but systemic. The Senegalese electrical grid is designed for stable demand, not for variable loads like those of electric buses. To address this asymmetry, a demand-side management (DSM) system must be introduced to shift nighttime loads when demand is low. This requires modifying the network control software and installing 500 advanced metering units at a cost of €15,000 each.
An alternative is the use of decentralized energy sources, such as rooftop photovoltaic panels. A 1 MW rooftop system can cover 20% of the energy needs of an electric bus, but requires an initial investment of €800,000 and a payback period of 8 years. This model can only be replicated if integrated with incentive policies that reduce the initial cost to 60%.
The Coexistence Strategy
The electricity producer in Senegal must recognize that the transition is not a linear process. The current grid capacity is a structural constraint, not a temporary obstacle. Investing in DSM and decentralized sources does not eliminate the bottleneck, but makes it manageable. It seems clear that the balance between supply and demand requires a coexistence strategy: one cannot wait for the construction of new transmission lines, but can optimize the use of existing resources.
The current phase is not a setback, but an entry into a more mature age of the transition. The producer must get used to operating with reduced margins and integrating different technologies. Only through this technical maturity can continuity of service and sustainability of the model be guaranteed.
Photo by Clément SAINT-MARTIN on Unsplash
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