The World Health Organisation lists air quality as the greatest environmental risk to health at a global level and estimates that outdoor air pollution exposure is responsible for almost seven million deaths every year. It puts emphasis on the urgent need for cities to decarbonise transportation
Urban areas are disproportionately contributing to global transport emissions. Growing global urban populations and their high population densities result in a significant share of total passenger journeys and goods deliveries.
Therefore, a substantial positive environmental impact can be made by decarbonising urban transport emissions globally. In a joint effort with Enel Foundation, Navigant, a Guidehouse company, investigated the opportunities offered by the electrification of public transport in a study: Sustainable Urban Mobility: A Global Perspective on the Future of Electric Public Transportation.
The report envisages several important co-benefits and positive externalities for the residents of large urban areas in all global regions. The authors explored selected case studies from cities around the world to examine how different cities approach the problem of transport decarbonisation.
Each city faces a unique set of challenges resulting from not only local environmental problems, but also their transportation, technological, economic, and societal contexts. Consequently, a diverse range of solutions have been deployed in these urban environments, which can provide valuable insights and learnings for cities looking to decarbonise their public mobility sector.
Recent efforts to tackle adaptation and mitigation has taken an integrated approach to ensure transportation infrastructure is both low carbon and climate change resilient. Examples include cities integrating ecosystem-based adaptation (EbA) measures to remove concrete and hard surfaces.
Cities replace concrete with porous surfaces and green spaces to improve surface water draining along tramways (as seen in Bordeaux, France) and on a wider city scale (such as in Berlin, Germany). Using EbA measures such as urban planting, urban forests, greenspace, and waterways alongside transportation routes, cities create integrated cooling corridors. These measures reduce air temperature, improve air quality, and reduce heat-related mortality, which is a severe risk during heatwaves.
The Navigant study highlights that progressing the electrification of transport creates a strong nexus between the energy and transport sectors. This interaction is both a challenge and an opportunity, creating new business models, new market participants, and different technical solutions transforming both sectors and their respective industries.
Successful electrification of transport will depend on the ability of the electric system to support the energy transition. The transition to the carbon-neutral energy systems of the future poses new challenges to the electric system.
On the production side, electricity generation from variable renewable energy resources is intrinsically intermittent. On the demand side, new load patterns with potentially high peak loads emerge as the transport sector is electrified.
Furthermore, overall demand for electricity is rising due to global population growth and the ongoing electrification of heating with electric heat pumps. Power systems need to be prepared to address the emerging need for flexibility.
One way to tackle these new challenges and improve the overall power system stability is with demand response. By shifting the times of electricity demand, peak loads could be adjusted to the available supply, reducing congestions and the amount of reserve needed to balance the grid.
This form of ancillary service is successfully in use by large industrial consumers such as cement manufacturing, chemical processing, or aluminium plants, which offer demand response services to the grid by adjusting production peaks to periods of high availability of electricity. This mechanism can be compared to a virtual battery.
EVs as grid energy storage assets
As electric vehicle (EV) batteries become less costly and more durable each year, their potential to offer demand response services increases. R&D of new battery chemistries and formats are increasing both energy density and durability.
These developments reduce the risks tied to premature battery degradation resulting from increased battery use for non-motive purposes. These advances are critical to improving mass-market adoption of EVs and enabling EVs as grid energy storage assets.
A study by the European Federation for Transport and Environment (Batteries on wheels: the role of battery electric cars in the EU power system and beyond) analysed the impact of EVs and storage on the electric system of four European countries in 2040.
It estimated that smart charging would deliver net cumulative benefits in France, UK, Spain, and Italy for about €4.3 billion per year. Smart charging of EVs would increase the system’s flexibility, reducing investments required to balance the grid. The study also found that overnight charging will consume energy generated by wind plants that would otherwise be curtailed.
The synergy between EVs and variable renewable energy resources is strong in the case of e-buses, which can act as giant batteries on wheels with predictable demand patterns. Electrified bus fleets could be instrumental in supporting system integration and reducing future grid reliability problems as EVs penetrate the vehicle market.
Bidirectional charging of EVs enables vehicle-to-grid (V2G), vehicle-to-home, and other potential vehicle-to-X applications. It represents another recent technological advancement that can play a major role in the future energy system, increasing the share of renewables in the mix and the number of prosumers.
By means of a bidirectional charging station, it is possible to consider an EV not only as an electric appliance, but also as an innovative means to store energy and provide balancing services. V2G technology potentially enables all vehicles to offer ancillary services.
Unlike private vehicles, public transport typically follows a regular and predetermined timetable that facilitates the scheduling of both charging and discharging to the grid. For this reason, new e-mobility offerings provide a better consumer experience compared with internal combustion engine (ICE) vehicles and they can also help to balance the grid.
With extensive application of V2G and vehicle-to-home solutions, it is possible to aggregate a critical mass to enable power grid stabilisation solutions, shaping the future of energy management. ESI
Sustainable Urban Mobility: A Global Perspective on The Future of Electric Public Transportation; authored by Sagie Evbenata, Scott Shepard, Ryan Citron, Ajay Chawan, Korinna Joerling, and Sam Abuelsamid from Navigant, a Guidehouse company; and Mirko Armiento, and João Duarte from Enel Foundation.
Batteries on wheels: the role of battery electric cars in the EU power system and beyond; report prepared by Element Energy and produced under the Study on EV Batteries project, commissioned and funded by Transport & Environment, in collaboration with Renault-Nissan, Enel Foundation, and Iberdrola.