Seventy percent of global greenhouse gas (GHG) emissions are accounted for by cities [1
], where the energy supply sector is the largest contributor of these emissions [2
]. As presented by Sperling et al. [3
] and Nilsson and Mårtensson [4
], for instance, some cities can have highly positive attitudes towards ambitious energy policies.
Although these studies found positive willingness by cities to follow national energy policies, they also found some major weaknesses. Sperling et al. [3
] identified the need for central coordination, and Nilsson and Mårtensson [4
] found local energy plans often to be vague. Similarly, from an urban development perspective, several previous studies have exemplified how energy planning needs to be integrated more into urban planning and urban development processes in order to execute low carbon development effectively [5
]. Additionally, it has been questioned whether an integrated approach to land-use and transport planning brings about the carbon emission savings often expected from the municipalities in the transport sector [13
Despite the limitations in GHG reduction capability, numerous cities have committed to reaching carbon neutrality within a certain time, and sometimes before national carbon neutrality targets. Carbon neutrality targets have been set by New York—2050 [14
], Stockholm—2040 [15
], Berlin—2050 [16
], London—2050 [17
], and Copenhagen—2025 [18
], for instance. Copenhagen’s target was set prior to the national carbon neutrality target. Other cities are relying on the carbon neutrality of the energy supplied by the national grid until the target year. Due to the importance of the matter, consortiums such as Cites40 [19
], Covenant of Mayors [20
], and ICLEI [21
] have been organized to advance the goal of carbon neutrality and general carbon reduction actions in their member cities. Cities40 is a coalition of 94 of the world’s largest cities. Covenant of Mayors is an EU-established initiative implementing climate objectives in nearly 10,000 local government organizations. ICLEI is a global initiative including more than 1750 local government organizations committed to sustainable urban development, from which more than 100 have committed to carbon neutrality. Several papers have studied the efficiency of municipal energy planning and the need to integrate it more into urban planning and urban development processes. Still, research on the capability of municipalities to create actual carbon neutral cities is lacking.
In such research, the scope of choice from which the emissions that the city directly or indirectly causes are included in their assessment is of high importance. One widely recognized scope system is that of the GHG Protocol [22
]. They have defined three different levels: Scope 1 refers to GHG emissions from sources located within the city boundaries; Scope 2 refers to GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam, and/or cooling within the city boundaries; and Scope 3 refers to all other GHG emissions that occur outside the city boundaries as a result of activities taking place within the city boundaries.
C40 Cities’ definition of a carbon-neutral city [23
] states four criteria for the carbon-neutral city: 1. Net-zero greenhouse gas emissions (annual emissions are completely cancelled out through carbon offsetting, or removed through carbon dioxide removal or emissions removal measures) from fuel use in buildings, transport, and industry (Scope 1), 2. Net-zero greenhouse gas emissions from the use of grid-supplied energy (Scope 2), 3. Net-zero greenhouse gas emissions from the treatment of waste generated within the city boundaries (Scope 1 and 3), and 4. Where a city accounts for additional sectoral emissions in their GHG accounting boundary, net-zero greenhouse gas emissions from all additional sectors in the GHG accounting boundary. C40 Cities also propose an alternative consumption-based approach, but the first production-based approach has been widely adopted, and is used as a definition of a carbon-neutral city in this study as well. The definition is widely used and thus justified to be used in this research. Figure 1
explains the scope definition as described by GHG Protocol [22
In Finland, all major cities have made carbon neutrality commitments; the capital city Helsinki has committed to be carbon neutral by 2035 [24
], Espoo by 2030 [25
], Vantaa by 2030 [26
], Tampere by 2030 [27
], Turku by 2029 [28
], and Oulu by 2040 [29
]. The national target of carbon neutrality is set for 2035 [30
], so Espoo, Vantaa, Tampere, and Turku are following the example of Copenhagen by introducing more ambitious city-level targets.
This paper’s aim is to evaluate how carbon-neutral city status can be achieved when the surrounding national or state-wide system does not yet support the neutrality. The study focuses on the energy sector’s GHG emissions. The research utilizes a case study of the City of Vantaa due to the availability of high-quality research material. It is conducted based on a process document review together with interviews of the key personnel who are guiding the work toward the carbon neutrality goal.
It will be shown that the City under assessment outsources the majority of the actions needed to secure the status of a carbon-neutral city to the state and the private sector. In addition, it does not allocate its electricity generation from Scope 1 or 2 to itself, thus limiting its capability to reach the carbon neutrality target. When justifying such scope allocation, the potential for carbon neutrality increases dramatically and allows carbon compensation actions, for instance, to be made for other sectors as well. The paper also discusses whether cities should invest in Scope 3 energy production in order to achieve further reductions in their carbon footprint.
The results showed that in terms of the number of processes, the City’s general approach to the achievement of carbon-neutral city status is mostly through decreasing consumption, focusing heavily on the energy efficiency of the building stock together with distributed renewable energy production. Most of the processes are not mandatory, thus limiting the City’s capability to steer the generation. The only mandatory process related to the production perspective is centralized district heating energy production, which is owned by the City, and thus within its jurisdiction. This process potentially eliminates carbon emissions occurring as a result of such energy production. The carbon decrease potential of district heat production represented 30% of the City’s total carbon emissions in 2016 and 58% of the energy sector’s GHG emissions. The consumption of electricity represents 22% of the City’s total carbon emissions in 2016 and 42% of energy sector’s GHG emissions. The amount of electricity produced by CHP was 33% of this. This electricity production is not allocated to the City. If it were, the City’s GHG emissions would initially increase, but it would increase its potential for carbon reduction measures.
Whereas the allocation of scope 1 emissions and GHG emissions from local municipal electricity production to the City is simple to justify, although not done here, GHG emissions from Scope 2 energy production have to be considered more on a case-by-case basis. Where carbon credits or compensation are offered from various sources, potentially allowing such affordable allocations to be made, one has to be aware of whether the allocation of such can be justified for carbon accounting. The municipal energy company owns shares in renewable electricity production sites.
Although electricity is purchased from the markets, the allocation of such electricity production to the City can be justified, as investments in such energy production has been decided upon by the municipality. When co-owned electricity production is included, the share of municipality-produced electricity rises to 74%. Co-owned production is completely renewable. Thus, when co-owned production shares are allocated to the City, municipal processes mean the City is 89% carbon-free from an energy sector perspective.
Even though the C40 Cities carbon-neutral city definition [23
] allows such allocation of out-of-city-boundary energy production, the City has not recognized this. Centralized electricity production is seen as an out-of-city-boundary and energy production company matter influencing City emissions through the grid emission implications.
Limiting the City’s boundary from electricity production increases the responsibility of external parties and limits the City’s capability to achieve carbon-neutral city status. Thus, the responsibility of a truly carbon-neutral city is shifted to the energy industry and central government. Additionally, private sector energy efficiency and distributed renewable energy production measures are indirect and instructive in limiting the influence of the City’s direct and mandatory measures to −58% from stationary energy system carbon emissions in 2016. It is thus seen that the major responsibility to ensure carbon neutrality belongs to central government, international organizations, the energy production sector, and real estate owners.
From the municipal organization perspective, this finding is in line with former research. Sperling et al. [3
] found the need for central coordination in municipal energy planning activities in Denmark. Nilsson et al. [4
] argued that municipal energy plan goals can be rather vague. Nystedt et al. [6
] highlighted the importance of legislation in the energy-efficient city.
On the other hand, a willingness to adapt different approaches for the achievement of carbon-neutral city status, when these measures can be justified, was identified in this study. Similarly, Madlener and Sunak [9
], for example, suggested that urban planning will be pivotal for a sustainable energy future. Studies within this field concern urban energy planning and integrating it more into existing urban planning processes. Research regarding the process of achieving absolute carbon-neutral city status is still lacking, which might partly contribute to the lack of execution plans for carbon-neutral cities and the allocation of centralized electricity production for cities. The allocation of such energy production for cities might be the only tool some cities have for achieving carbon-neutral city status. In most cases, it can be assumed that this also means the allocation of energy production beyond the physical city boundaries.
As cities’ approaches toward carbon reduction have been seen to be more bottom-up in the literature, focusing on increasing the energy efficiency of buildings and integrating distributed renewable energy production, this case study city’s approach was similar, with its limited control over securing the production of carbon-free energy. When developing a truly carbon-neutral city, one has to focus on net-energy flows and their emissions. Thus, it could be proposed that an efficient approach to reaching such a status and ensuring an efficient transition toward it should combine both bottom-up and top-down approaches. As a result, consumption-based energy efficiency measures would be taken into account in parallel when securing the transition to carbon-free energy production. For cities, this means that shares in energy production investments would be included in CNAP, with this production allocated to the City. Where this is not reasonable, proven annual carbon compensation mechanisms should be included to make sure that the annual net-carbon balance is zero or negative, regardless of the actual capability to shift toward complete net-zero emissions. For transparent statistics and carbon accounting, allocated energy production should be separated in the statistics so that actual carbon emissions can be calculated for the sectors and cities. Without this separation, double counting will exist. When considering cities such as Espoo, Vantaa, Tampere, Turku, and Copenhagen achieving carbon neutrality prior to national carbon neutrality, the importance of out-of-city-boundary energy investments and allocations can be seen as necessary. Even for those cities achieving carbon neutrality after it is achieved nationally, such investments are likely to be mandatory if consumption-based carbon accounting is added and/or compensation is needed.
There are certain limitations in this study which should be noted when drawing final conclusions. First, the study used the required actions for carbon neutrality prepared by the City as they are. Thus, where these actions are potentially incorrect for achieving carbon-neutral city status, the study repeats this error. Secondly, all the indirect measures and their potential were excluded from the study, underestimating the potential of the City from this perspective. On the other hand, the study also excluded the shares of future energy sector-based GHG emissions and the potential currently within GHG emissions from segments other than the energy sector—most importantly, the future electricity consumption within the transportation sector. Whilst the transportation sector is the second-highest GHG emitting sector for the City, and its electricity consumption will most likely increase dramatically, the City’s capability to take responsibility for the carbon-neutral city status increases, as it can react to this consumption increase with additional carbon neutral electricity production. Thirdly, the assessment follows scenarios and assumptions of the future, which weakens the reliability of the study.
In addition, the municipal energy system is highly interlinked with waste disposal. Thus, changes in waste supply have a direct influence on energy systems. Anaerobic digestion of waste food, for instance, would offer great potential for further synergy between these sectors [42
The study included only energy-sector GHG emissions, which doesn’t represent the complete carbon emissions of the City. The share of energy sector GHG emissions is 52% of total GHG emissions. As stated earlier, the remaining share is dominated by emissions from the transportation sector. As the remaining carbon emission sources are seen to move more into the energy sector, this increases the potential of municipalities to take responsibility for the carbon-neutral built environment—that is, as long as centralized electricity production is allocated to the City and seen as a tool that the City can utilize and take responsibility for. Similarly, when changing carbon accounting to a consumption-based approach, the City’s GHG emissions would probably increase significantly. Thus, it would be natural for the City to also compensate these GHG emissions through securing carbon-free energy production within a larger system. Doing so within the national or Scope 2 boundary would be relatively simple. To compensate global or Scope 3 GHG emissions, appropriate shares in related energy production funds could be considered, for example. Where this paper studied a reference year, it is important to recognize that system changes are rather dynamic, changing annually and influencing the potential for how carbon neutrality could be achieved. Similarly, while the shares of fossil fuels are decreasing, consumption from grid-supplied energy systems is likely to increase, which changes the carbon neutrality requirements accordingly.