Urban path to net-zero: leading strategies of most energy-efficient cities
Cities are at the heart of the global transition to net-zero. This is not a surprise because a massive part of the world’s economy is centered around cities: businesses, commerce, trade, and society. Cities represent only 3% of the earth’s land but are home to more than half of the world’s population and account for an estimated 80% of global gross domestic product (GDP), according to the 2020 data (“Renewables in cities, 2019 global status report.” Ren21).
It is projected that nearly 70% of the world population will live in cities by 2050 (“To achieve net-zero carbon cities and buildings we need systemic efficiency.” World Economic Forum). Further urbanization, population growth, economic development, especially in emerging markets, and rising standards of living are expected to contribute to growing energy demand in urban areas. Cities are also centers of global economic activities with a high concentration of industry, businesses, infrastructure, transportation, and shipping consuming large amounts of energy that goes beyond energy use in cities only. Because of their large energy and environmental footprints, cities are responsible for approximately 75% of all carbon emissions from global energy use and play a major role in contributing to climate change. Cities' transition to clean and renewable energies is crucial to decarbonize the energy system and meet the objectives of the Paris Accord agreement.
Cities around the world are joining in the global efforts to reduce the dramatic impacts of climate change and transition to cleaner and more sustainable living. They are taking important steps in developing their own energy, climate, and sustainable development strategies. However, not all levels of commitments are equal, and not all progress is the same. Some cities are significantly ahead of their peers in terms of setting ambitious goals, developing and implementing green strategies, and tracking the progress. Others need more guidance on how to turn their commitments into actions. (This section has been shortened from its original version.)
Strategies and approaches to city transition reaching climate goals
When developing net-zero carbon strategies, cities are driven by a range of objectives, including mitigating climate change; advancing sustainable development; reducing air, water, and soil pollution; improving citizens’ health and wellbeing; stimulating economic development; reducing municipal energy costs; and improving energy access and security (“Drivers for renewable energy cities,” REC-19, Figure 5, page 38). Depending on its geography, size, demographics, economic factors, and administration, a city may put a different level of importance on each driver and most cities pursue renewables for a diversity of reasons.
Targeting the most energy-intense sectors and categories will lead to the biggest impact when meeting net-zero energy goals. Successfully attacking these problems will yield the biggest payoff on the effort of investment, potentially reducing 50% or more of carbon emissions due to elimination of energy inefficiencies while at the same time improving the quality of life by reducing air and noise pollution, energy costs, and road congestion and increasing reliability and efficiency of electricity supply. This is what every city will have on its agenda although dealing with these problems can be highly complicated. According to Figure 3 below, buildings are the largest category of energy users and account for approximately half of all energy demand globally. Space heating and cooling offer the biggest opportunity for decarbonization, as these activities occur locally and can be handled in a decentralized manner at or close to the point of use. Second, transport accounts for 32% of total final energy consumption. Improving urban mobility and transitioning public transportation to renewable options could significantly reduce the levels of air pollution and carbon emissions, making cities more walkable, accessible, and environmentally friendly. Finally, the remaining 17% goes to general power use which includes utilities and lighting (Figure 1, REC 2019, page 29).
To achieve net-zero carbon and sustainable development goals to support population growth and increasing economic activities, cities need a long-term commitment and a systematic approach to solving the problem. Energy efficiency is one of the best ways to achieve lower levels of energy consumption which would dramatically move us closer to reaching sustainable goals. It is estimated that society can reduce energy use by 50% or more through conservation efforts, better energy use practices, and energy-efficient appliances. It is less costly to save energy than to generate it from any source. Aggressive transition to renewable energies will solve the remaining part of the challenge. It is projected that renewable energy can supply two-thirds of the total global energy demand and contribute to the carbon emissions reduction at the levels needed to achieve the net-zero goals by 2050 (“The role of renewable energy in the global energy transformation,” D. Gielen et al.).
Cities can tackle net-zero ambitions using the following strategy:
· Building new buildings to operate at net-zero emissions
· Maximizing the use of renewable energy sources
· Assessing the role of energy efficiency to reduce energy consumption and lower energy bills especially for the low-income communities
· Leveraging new technologies and artificial intelligence (AI) for smart grid management
· Education and community engagement
· Well-designed policy instruments
· Public-private and financial partnerships
All these goals can be and are being achieved with existing technologies already available today (“How to achieve zero-carbon cities and buildings.” World Economic Forum). Technological innovation continues to bring more and more progress — an effective transition calls for integrated energy solutions, backed by ambitious policy and urban planning, as well as community participation and public-private partnerships.
> Sustainable cities case study 1: Copenhagen, Denmark
> Sustainable cities case study 2: Boston, MA
Leveraging best practices
At the heart of any city’s transition initiative should be building, transportation, energy, and water utility policies. Buildings are responsible for 70% of city carbon emissions. Reducing energy consumption in offices, residential buildings, and homes will be most impactful. Cities can expand community solar projects, storage capacity solutions investment, and energy efficiency educational programs to promote energy reduction opportunities. Transportation projects such as improving public mobility, vehicle electrification, accessibility of EV charging, modernizing airports and harbors are the second-largest category for city climate changes. Energy and water utility practices such as smart monitoring, even distribution, and offloading during peak hours, can be highly effective. A multi-use approach and multipurpose utilities are a way to the future. Homes could use the same water many times for landscaping, gardening, and toilet water — as much as 75% of domestic water can be reused (“How to build a water-smart city.” Bloomberg). Similarly, water purification and energy generation can be done by a single utility, which could be a cost-saving direction of the future for large wastewater and power generation plants (“Water utilities venture into energy generation to save money.” Water World). Artificial Intelligence (AI) and smart automation can also play a powerful role in analyzing usage, predicting the peaks, and optimizing load on the systems. Utility companies will have to decide if they are working with software companies, or if they want to become software companies in their own rights to manage decentralized grids, balance electricity supply and demand in real-time, and optimize energy use at reduced rates (“Why artificial intelligence is key to renewable energy grid resilience.” World Economic Forum, 30 March 2021). Weather predictive technologies (such as Tomorrow.io) offer innovative solutions for multiple industries, including weather intelligence for Energy and Utilities to plan to minimize downtime, optimize safety, and reduce costs. Finally, to be good global citizens of the future, cities must set sustainable goals based on mitigation and adaptation approaches and build in a new way instead of rebuilding back the old systems that no longer can meet the needs of the planet and future generations.
Transitioning cities to sustainable operations is a must to ensure the future of our planet. There are major components in meeting the goals: technology, funding, policy, and implementation. The technology component is already here; there are major commitments from the government, public and private sectors to provide funding; however, policy and implementation in many cases are still lagging. Reaching global net-zero emissions goals will require outlining plans for developing and realizing effective decarbonization strategies. Making a pledge is a good start; following with an actionable plan is a critical next step. Cities must learn from each other and take action to meet the pressing deadlines.
Accelerating Net-Zero. Data-Driven EnviroLab and Newclimate Institute, 09/2020: datadrivenlab.org/wp-content/uploads/2020/09/Accelerating_Net_Zero_Report_Sept2020.pdf
 Renewables in Cities, 2021: www.ren21.net/wp-content/uploads/2019/05/REC_2021_full-report_en.pdf