An international research team has used data from Beijing’s public transportation system to investigate whether bus depots could house solar installations and energy storage facilities to help reduce the burden on the city’s grid. The researchers say they plan to generalize their proposed model to help other areas estimate the potential return on investment from transforming other civilian infrastructure into energy hubs.
An international research team led by the University of Utah has explored the potential of installing on-site solar and energy storage at existing bus depots.
The research is based on a case study from Beijing. The Chinese capital is home to the world’s largest public transport system, with 27,000 buses, more than 90% of which are low- or zero-emission vehicles. The battery-operated buses are charged via a network of more than 700 bus depots spread over 6,500 m². The infrastructure runs parallel to and can put pressure on the city’s electricity grid.
The study combined a computer model of Beijing’s bus network, consisting of 2020 data on air temperature and solar radiation at each depot, with the roof area of each depot, to predict the electrical output of the solar panels that could be installed there.
The scientists found that solar energy could reduce the net charging load on the electricity grid during electricity generation periods by 23% and reduce the net peak charging load by 8.6%. Variation in supply and demand between depots was noted, with busier depots better able to make the most of a day of sunshine, while more remote depots would need to store or redistribute their excess electricity.
Integrating energy storage would increase the reduction in net charging load on the electricity grid by 28% and reduce net peak charging load by 37.4%, the researchers found. A cost analysis concluded that unsubsidized solar installations would generate profits 64% above costs, while adding battery storage would reduce profits to 31%.
“We found energy storage to be the most expensive factor in the model, so smarter and strategic charging schedules should be implemented,” said Xiaoyue Cathy Liu, one of the report’s authors. “That responsiveness is critical because variable energy price regulations have such a major impact on the overall economy.”
The study also highlights the economic benefits and CO2 emissions reduction as other benefits for transforming public transport stations into profitable energy hubs.
“This study advances our understanding of the synergistic benefits of combining these technologies and provides actionable insights for policy makers, urban planners and the sustainable energy community at large,” the academics said. “By demonstrating the viability and economic benefits of such a model, policymakers could be encouraged to prioritize similar renewable energy strategies, potentially accompanied by incentive mechanisms, to accelerate city decarbonization efforts.”
The researchers say they plan to generalize the proposed model further, to provide other areas with a method for estimating the return on investment of transforming bus depots or other parts of civil infrastructure into energy hubs.
Their findings are available in the study “Transforming public transport depots into profitable energy hubs”, which was recently published in nnatural energy. The team also included academics from China Beihang UniversitySweden Chalmers University of Technology and that of Germany Fraunhofer Institute for System and Innovation Research ISI.
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