Cities are both consumers and producers of energy. They account for around 75% of global energy usei and are the leading growth markets for utilities.1 Because cities (including their governments, inhabitants, and commercial and industrial entities) use so much energy, they have the potential to drive large amounts of renewable energy deployment. However, cities worldwide vary greatly in their energy use – depending on factors such as the level of economic development and the presence of industry, among others – and in their overall ability to deploy renewables, which may reflect local resource and other constraints. In 2020, the COVID-19 pandemic sharply reduced energy use in many cities, particularly in the transport sector (→ see Sidebar 1 in Global Overview chapter).2
City governments often are constrained by policies and regulations at higher levels of government, as well as by the availability and condition of energy distribution infrastructure. When provided sufficient autonomy, however, a city can exercise greater flexibility over its energy mix and define, to a large extent, the trajectory of its energy future. Overall, cities have significant opportunity and potential to steer the energy system towards renewable energy – not just locally, but well beyond.
Globally, a relatively small but growing share of the energy consumed in cities comes from modern renewable sourcesii . To some extent, this renewable share is expanding in direct proportion to developments outside of the urban purview, thanks to the greater deployment of renewables elsewhere. For example, state/provincial or national mandates, as well as the changing economics of energy technologies, have led to rising shares of renewable electricity or fuels in regional grids – which has led to higher city shares as well. At the same time, more and more cities worldwide are directly increasing their production and consumption of energy from renewable sources.3
Urban demand for renewables is rising in response to growing recognition of the diverse economic, environmental, social and other benefits associated with renewable energyiii . So far, the greatest focus has been on meeting municipal government demand (via city procurement authority) followed by efforts to reshape the wider urban energy supply and demand structure. Private procurement also plays a growing role, as individuals and businesses determine their own renewable energy needs. Although most of the renewables used in cities are still sourced from outside the urban area (through regional grids, pipelines and other infrastructure), local production of renewable energy – in the forms of electricity, direct thermal energy and transport fuels – is significant and growing.4
Around the world, city governments as well as urban households and commercial and industrial actors are shaping their energy infrastructure and use to better accommodate rising shares of renewables. They are expanding district heating and cooling networks, implementing efficient end-use technologies, increasing electrification of the transport and heating sectors, installing energy storage capacity and facilitating greater flexibility on the demand side – all of which can provide benefits such as greater system efficiency, improved reliability of service and lower overall system costs.5 To address multiple urban challenges in a cost-effective manner, city governments also are linking energy supply with other municipal activities – for example, using rapidly growing urban waste and wastewater streams as feedstocks to produce solid, liquid and gaseous biofuels (→ see Sidebar 5).6
The availability and reliability of energy data vary greatly across countries and cities. In general, data on renewable energy capacity and generation are tracked at the national (and often state/provincial) level, but not always at the local level. As a result, comprehensive global statistics on urban renewable markets (for both energy and technologies) and generation are incomplete or lacking.7 Further, although energy consumption is reasonably well documented at the national level, the urban/rural breakdown of this use is generally unavailable.
Within these limitations, this chapter provides an overview of city-level renewable energy market and infrastructure developments during 2019 and 2020. It examines the installation of renewable energy technologies and associated infrastructure in cities, the energy capacity procured for use in cities, as well as relevant consumption trends across the buildings, industry and transport sectors (→ see Global Overview chapter).
iiIn many cities (especially in sub-Saharan Africa), the traditional use of biomass for heating and cooking is still widespread. See Glossary for definitions of modern renewable energy and traditional biomass.ii
iiiSee Drivers chapter in REN21, Renewables in Cities 2019 Global Status Report (Paris: 2019), https://www.ren21.net/wpcontent/uploads/2019/05/REC-2019-GSR_Full_Report_web.pdf.iii
SIDEBAR 5. Waste-to-Energy in Cities
The rise of urban refuse, including municipal solid waste (MSW) and wastewater, has been a major component of the rapidly growing global waste streami. As the volume of refuse in urban areas skyrockets – driven by population growth, urbanisation and changing patterns of consumption – cities have faced major challenges, leading many to undertake measures to improve their waste management systems.
Key challenges include: the effective and comprehensive collection and transport of refuse to waste processing facilities; separating and capturing recyclable materials and energy content from the waste stream (including methane emissionsii); and identifying adequate land for treatment and disposal of remnants (often at high economic cost) – all while minimising the impacts on public health from local air, soil and water contamination. In developing countries and emerging economies, more than two-thirds of MSW is deposited improperly in open landfills that lack advanced environmental protection, let alone adequate energy and material recovery protocols.
At the same time, waste is a resource that, if properly recycled, can be recovered to be used as an input for new products. Cities have numerous opportunities to manage their waste in a more sustainable (and economically beneficial) manner. To minimise the volume of waste going to landfill and to recapture both material and energy resources, many cities divert, capture and recycle usable materials. Any refuse with direct energy potential (meaning usable fuel and direct heat, as opposed to recaptured embedded energy in materials such as processed metals) can be captured for direct and indirect energy applications.
For example, organic waste can be extracted and reformed into solid, liquid or gaseous biofuels to generate electricity, to directly provide heat via combustion (for cooking and heat in buildings, and in industry) and to fuel vehicles. Organic waste also can be processed into organic fertiliser, which displaces demand for fossil fuel-based fertilisers and avoids emissions associated with using fossil fuel as a feedstock.
To extract energy from waste, cities have adopted a variety of technologies, including anaerobic digestion of solid and liquid organic waste to produce biogas, the capture and use of landfill gas, and direct combustion of solid wasteiii. Biogas, whether from digesters or landfill, is considered to be a renewable fuel. It has high methane content and can be combusted directly to produce electricity and/or heat.
In Santiago (Chile) in 2017, the water utility Aguas Andinas transformed three wastewater treatment plants into the Greater Santiago Biofactory, which converts the city’s effluent to biogas to produce heat and electricity; the utility also reuses the additional sewage sludge as fertiliser for agriculture. In 2019, the plant generated 57.2 gigawatt-hours (GWh) of electricity and reused 69% of bio-solid as fertiliser. In Victoria (Australia), the Environmental Protection Authority approved construction in 2020 of a second biogas plant at the Melbourne Regional Landfill, which is expected to generate 68,000 MWh of electricity annually.
Cities also are converting food waste to biogas. In the United States, both legislation and public demand to limit landfill sizes and reduce carbon footprints has motivated city actors to take action. In 2020, Los Angeles (California) expanded the capacity of its food-to-biogas plant from 165 tonnes to 550 tonnes of separated food waste per day, which is used to produce fuel for electricity generation and for transport vehicles. In New York City, the Newtown Creek Wastewater Treatment Plant has processed around 3% of the city’s daily liquefied food waste into biogas for electricity generation since 2016, and plans were announced in 2019 to double the plant’s capacity.
New Zealand was building its first large-scale food waste-to-biogas plant with anaerobic digester technology in Reporoa on the North Island in 2020. The facility, expected to be operational in 2022, aims to process up to 75,000 tonnes of household and commercial food waste from Auckland annually to provide electricity for the equivalent of around 2,500 households in the region and to provide bio-fertiliser for 2,000 hectares of local farmland, as well as to produce CO2 and heat for local greenhouses.
Biogas can be upgraded to biomethane and used as a transport fuel or injected into fossil natural gas pipelines. Biomethane plants have become increasingly common, particularly in Europe where the number of facilities rose 51% between 2018 and 2020, from 483 to 729. Lille (France) converts more than 108,000 tonnes of household waste annually into biomethane to fuel half the city’s bus fleet. In 2020, Bristol (UK) partly funded the deployment of 77 buses fuelled with biomethane derived from anaerobic digestion of food waste. Toronto (Canada) partnered with the gas company Enbridge Gas to install biogas upgrading equipment for biomethane production at the Dufferin Solid Waste Management Plant. The facility is expected to produce some 3.3 million cubic metres of biomethane per year for injection into the natural gas distribution grid, which supplies fuel to waste collection trucks and other municipal vehicles as well as heat for Toronto’s buildings and other facilities.
The direct disposal of MSW through incineration is a common practice, and more than 4,800 incinerators are in operation worldwide, a growing number of which use the thermal energy released through combustion to generate usable heat and electricity. However, only the energy produced from the organic portion of MSW can be considered renewable, and emissions from incineration greatly affect air quality in the absence of pollution control systems. Cities have begun to install control systems to reduce air emissions from incinerators. In 2018, the Norwegian government initiated a carbon capture project at the Klemetsrud waste-to-energy facility – which processes more than 400,000 tonnes of waste annually – to generate electricity and heating for the city of Oslo. In 2019, the Dutch waste-to-energy company AVR equipped its waste combustion plant in Duiven (Netherlands) with a flue gas purification system to reduce CO2 emissions.
Source: See endnote 6 for this chapter.
iiMethane, emitted during the decomposition of organic wastes, is a potent greenhouse gas that contributes to climate change and can potentially cause explosions at waste facilities if ignited.ii
iiiNot all energy produced from the remaining waste is renewable. Energy derived from MSW combustion cannot be considered entirely renewable, as MSW also contains inorganic material. Generally, about 50% of this energy is classified as renewable.iii