Copenhagen, Denmark (population of 799,033 as of 2020)
Copenhagen aims to be the world’s first carbon-neutral capital city by 2025 (The CPH 2025 Climate Plan, Copenhagen — Urban Development). Politically, the city also intends to demonstrate how it is possible for big cities to combine growth, development, and an enhanced quality of life while reducing carbon emissions at the same time. This goal sets Copenhagen as a frontrunner in the international arena.
Copenhagen designed its Climate Plan Roadmap in three phases and set on the first phase of the net-zero journey in 2013 with the ultimate goal to become carbon neutral by 2025. The plan was developed in line with the emergence of new knowledge and technology, as continued innovation allowed to make carbon reduction strategies possible and at scale. At the same time, the CPH 2025 Climate Plan seeks to enhance the quality of life for Copenhageners using carbon neutrality goals to change behavior and stimulate innovation, job creation and investments.
By 2018, Copenhagen has successfully achieved a reduction of carbon emissions per capita by 57% while the city’s population grew by 22%. This reduction was mostly due to the green conversion of power-generation and district heating systems from coal to biomass and the erection of wind turbines.
Figures 5, 6: Copenhagen carbon emissions actual and projected, 2005–2025
According to Figure 6, while the 2018 progress has been remarkable, it will require significant additional efforts to reach the 2025 targets. This aggressive goal is based on the city’s climate plan’s four pillars: (1) Energy consumption, (2) Energy production, (3) Mobility with reduced emissions, and (4) City Administration initiatives.
Energy consumption. This pillar primarily focuses on achieving energy efficiency for district heating and transitioning from oil to renewable energy systems. City of Copenhagen collaborates with large building owners on efficient management of their properties by monitoring their energy consumption and optimizing building operations.
Energy production. Copenhagen is powered mostly by renewable energy with more than 50% of electricity supplied by wind and solar, and approximately 80% of all electricity coming from renewable energy sources including bioenergy and geothermal energy (“A record year: Wind and solar supplied more than half of Denmark’s electricity in 2020.” State of Green). The city has ambitious efforts to add at least 460MW from wind turbines by 2025.
Mobility covers two groups of transportation: road and maritime. The city plans to convert all its public busses, road and harbor busses, to renewable energy sources and run on electricity, biodiesel, bioethanol, biogas, natural gas-electric hybrids or hydrogen fuel cell busses. The city is looking to expand public transportation and promote the use of bicycles to travel around the city. In addition to achieving a reduction of CO2 emissions, this initiative will have the benefit of significantly less street noise and reduced local air pollution (“Copenhagen aims to become a carbon neutral capital/Sustainable Transit.” Green City Times).
City Administration. This category sets an example for the Administration to lead the way to reduce the city’s energy consumption, green procurement and transition of the city’s vehicles and infrastructure to operate on alternative fuels. This is important in stimulating public-private partnerships, cooperation with other municipalities and other organizations, and engaging the citizens in the green transformation.
Copenhagen is showing an impressive reduction in carbon emissions. Two specific projects the city is proud of are EnergyLab Nordhavn and seawater use for cooling (“This is how Copenhagen plans to go carbon neutral by 2025.” World Economic Forum). EnergyLab Nordhavn is located in Copenhagen’s waterfront city district North Harbor. The EnergyLab was launched in 2015 in close partnership between academia, industry, utilities, and local government to design a full-scale smart city energy lab with innovative solutions in the areas such as intelligent waste handling, low-temperature district heating, clean public transportation, and super cycle highways. This project is looking at the whole energy system as one, integrating heat, electricity, and transport and testing new solutions such as large batteries and EVs to reduce peak load on the grid, intelligent heating of buildings, and a heat pump and storage system to improve flexibility and optimize local district heating network (“Cities 100: Copenhagen’s new Nordhavn neighborhood is a center of innovation for small energy systems.” C40 Knowledge).
Copenhagen also uses seawater from the harbor for its cooling system with the potential to cut emissions by 70% and keep about 80,000 tons of carbon out of the city’s direct atmosphere. In addition to the climate and environmental benefits, it costs less, takes up less space and it makes no noise. It works by pumping seawater of about 6C, using this water for the district water supply and returning water at about 16C back to the harbor (“Seawater keeps Copenhagen buildings cool.” Climate Change Adaptation).
This is a case study for the main article, Urban Path to Net-Zero: Leading Strategies of the Most Energy-Efficient Cities.
 World Economic Forum: This is how Copenhagen plans to go carbon-neutral by 2025. weforum.org/agenda/2019/05/the-copenhagen-effect-how-europe-can-become-heat-efficient
 Danfoss Engineering Tomorrow: Seawater cools Copenhagen, cutting 70% emissions. www.danfoss.com/en/service-and-support/case-stories/dds/seawater-cools-copenhagen-city-cutting-emissions-by-70