5.3 Decarbonization pathway
Since the late 1980s, city governments worldwide have been preparing and implementing plans and making investments to reduce their greenhouse gas emissions. Some measures to achieve this have included energy retrofits and fuel switching (from coal to natural gas to renewable electricity), in addition to other energy-efficiency measures in buildings and the utility, transportation and waste management sectors. Such measures have often led to net local reductions in energy costs along with net increases in local employment (European Parliament 2010; International Energy Agency [IEA] 2020). Hundreds of cities have now committed to achieving net- zero carbon emission targets for their buildings, for whole districts, and increasingly for the whole city. Bristol (the United Kingdom), for instance, has set a target of becoming a net-zero city by 2030 (Dudd 2019), while in 2019, Toronto (Canada), pledged to become net zero (including offsets) by 2050.3
Moreover, the European Strategic Energy Technology
Plan (SET Plan), launched in 2007 by the European Commission, supports the 100 Positive Energy Districts programme, which will advance the design, technology and finance practices needed to transform city districts across
Figure 5.6: Decarbonization pathway for cities
Optimize legacy assets and systems: reduce carbon and maximize efficiencies through fuels switching, equipment and process improvements, green building designs, and demand side management
Europe into net-positive generators of their own low- or no- carbon energy supplies (Bossi, Gollner and Theierling 2020). However, fully meeting the net-zero carbon targets currently being adopted by cities will require further systemic change.
Figure 5.6 illustrates the dual aspects of a general decarbonization pathway for cities. The vertical columns represent existing sectors and their “legacy” (i.e. outdated) infrastructures, which have been organized and regulated as separate, unintegrated systems. The start po of urban decarbonization efforts has typically involved the implementation of eco-efficiency measures and retrofits within each of these vertical operational areas and their systems and facilities, along with related adjustments to user behaviours. The last decades of urban greenhouse gas reduction efforts have mostly taken such a sector-focused approach, with sector- and facility-specific retrofits having included fuel switching, more efficient equipment and eco- building designs, demand-side management and related regulatory reforms and economic incentives, among others.
The horizontal columns in the figure represent integrated new systemsthat need to be developed to transform not
Transportation
Buildings
Power Sector
Waste
Bioenergy production systems from organic wastes and wastewater solids, including methane capture systems (which also addresses the challenge of urban methane emissions).
Food
Urban planning and development frameworks and models that establish energy efficient built forms and transit-oriented development patterns.
Regional biomass/food waste composting and biofuels system fueling transportation & power sector.
Regional industries organize waste exchanges and reduce carbon footprint of supply chains.
Establishment of a local/regional tourism sector involving regional food culture reduces sector transportation emissions, supports repurposing of existing building stock.
3 It is important to note that many of the net-zero targets being set by cities do not include their “scope 3” emissions or the emissions that the city influences upstream or downstream of its boundaries. For this reason, these net-zero targets need to be combined with a circular city approach so that the environmental impact of the full value change of the materials entering and existing in a city can be included.
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GEO for Cities
Develop new low carbon “nexus” systems by integrating across legacy infrastructure and operations as they are being optimized, thus transforming the nature and metabolism of the system itself
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