This section presents the knowledge acquired from evaluating and analyzing each servitization application towards the improvement of sustainability in an urban environment. Each case study was subjected to ex post application of the tools described before and their key attributes were identified along with steel’s contributions and challenges.
The servitization of electricity once bought as a product and delivered to a household merely for consumption into a localized and demand-specific solution, capable of reducing costs and adding consumer value, as seen in the study by Pinto et al. [56
], relied on two different factors: (a) Replacing a mostly hydraulic-based grid electricity supply with decentralized solar sources, and (b) retaining, redistributing and reusing excess energy within the local network by using feedback. The first factor contributes to reducing electricity demand from the installed capacity while reducing the demand for electricity distribution along the grid. On the other hand, the second factor not only contributes to the previous one, while providing economic benefits to the citizen, but also adds intangible values such as grid independence, community integration, and participation.
From the perspective of sustainable urban metabolism, the propositions of Pinto et al. [56
] help to partially transfer electricity sourcing from outside a city’s boundaries to the households within it, directly reducing the required external energy input while strengthening and empowering local stakeholders at the expense of an increase in material stock within the city’s boundaries. Furthermore, it reduces the amount of electricity wasted by over-generation as well as electricity lost during long range distribution. Cities in which such a project would be deployed would become altogether more resilient and sustainable while helping reduce emissions, losses, and wastes related to electricity generation.
When applying the criteria of circles of sustainability to this case study, several contributions were identified, as seen in Figure 4
. In the domains of politics and culture, minor benefits to “Organization & Governance” and “Engagement & Identity” were perceived, related to the required policy adjustments that would enable grid feedback and feed-in tariffs and to the creation of a local community of households of which roofs now include solar panels, respectively.
It was in the ecology and economy domains; however, that most contributions were perceived. Deploying photovoltaic solar panels onto the roofs of Brazilian households could significantly shift how electricity is used and consumed in relation to the existing matrix, potentially creating new service sector jobs related to installation and maintenance. Moreover, improving infrastructure by using new technologies is a good way to increase local wealth distribution, while promoting or changing how knowledge and capital are exchanged. Additionally, having a network capable of grid feedback also increases the need for proper and engaged accounting and regulation, especially if the study’s proposition of feed-in tariff cross-discounts is put in force.
Changing how electricity is generated also changes the materials necessary for the equipment used to generate it. Photovoltaic solar panels use considerably more silicon than iron in their composition, for example, in addition to other materials less pollutant to produce or less impactful to implement than hydraulic energy infrastructure. Consequently, both direct and indirect benefits to air quality, water quality, and reductions in the amounts of emissions and waste generated would be perceived throughout the entire system, thus improving the sustainability of the urban area it would be a part of, while potentially reducing the need for environmental impacts outside its boundaries as well.
Although steel presence in photovoltaic solar panels is minimal—around 3%, in the frame and in the installation hardware, consisting mostly of stainless alloys UNS S30400 and S31600 [73
]—it is important to note that the mainly hydraulic Brazilian energy matrix relies heavily on energy generation equipment made of steel and, even if the distribution itself depends mostly on copper and aluminum, steel-intensive machinery and structures are always present [74
The results available in the study by Pinto et al. [56
] point to an average of 153.25 GWh generated by 405,691 solar panels installed onto the roofs of 73,762 houses, the equivalent of the entire electricity generation capacity of the Jupiá hydropower plant in Três Lagoas, Brazil [75
]. Considering that an average hydropower plant contains 10,000 tons of steel in its structure [74
] and taking into account an average photovoltaic solar panel mass of 18 kg [76
], the participation of the steel present in the solar panels is about 0.7 kWh/kg of steel, while the participation of the steel present in the hydropower plant would be of approximately 0.015 kWh/kg of steel—45 times less.
It is important to note; however, that solar panels cannot produce electricity 24 h/day, thus requiring either energy storage or additional energy sources to fully supply the demands of a household. Considering the use of lithium ion batteries and only 10 h/day of solar irradiation, the previous result in the participation of steel in electricity generation falls to 0.24 kWh/kg—still 16 times better than hydropower alone for a period of 30 years of operation.
Furthermore, considering an energy intensity of 22.5 GJ/ton of steel [79
], producing all the solar panels and the required amount of batteries for this case study would consume approximately 5.35 TJ, while building the equivalent hydropower plant would require around 225 TJ for steel alone, with the notable addition of stronger and more complex alloys such as UNS S32205 and S17400 [73
This indirect reduction in supply-side steel intensity per kWh generated, coming as a result of demand-side servitization, points to one of the potential contributions of steel—in this case related to its quantity; although less steel is present, its participation is substantially more relevant. The challenge for steel, in cases like this, resides mostly in identifying where is the least amount of steel capable of providing the most environmental benefits (e.g., small amounts on a solar panel provide more environmental value than very large amounts in a hydropower plant).
By subsidizing a transition towards eco-efficiency within households and supporting it with maintenance—whether if by leasing or not—a city can turn appliances, previously acquired by its citizens merely as products to be used and discarded, into solutions capable of actively supporting the reduction of its required energy inputs as well as its emissions. Servicing this equipment and further supporting this initiative with the creation of green spaces and gardens capable of providing food, and consequently reducing the amounts of packaging, food waste, and transportation, poses as a solid contribution to sustainability.
As per sustainable urban metabolism, the study from Céron-Palma et al. [57
] contributes to reducing inputs and outputs, but minimally—if at all—to reducing stocks. The reduction of inputs derives mostly from the green spaces and gardens producing food and avoiding the need for packaging and transportation, while the reductions in outputs are most expressive regarding the energy savings provided by eco-efficient appliances and the consequent reduction in emissions. Céron-Palma et al. [57
] also present the possibility of carbon sequestration in the green spaces and gardens, but with almost negligible effects relative to the other benefits.
Although the amount of materials and food in stock would likely be unaffected, “Use & Consumption” patterns would change and, consequently, so would “Production & Resourcing”, as per the criteria of circles of sustainability. As summarized in Figure 5
, minor effects on most of the aspects of the economic and political domains would nevertheless provide substantial improvements in the ecology domain. These improvements would be directly related to increases in health and wellbeing, while contributing – even if marginally – to the creation of a locally-engaged community.
The intersections that exist between all of the aspects of the ecology domain ended up boosting each other; therefore, increasing environmental quality. This points to a reinforcing behavior which, whether intended or not by Céron-Palma et al. [57
], presents major long-term sustainability and resilience benefits; the less issues with emission and wastes, the better water and air quality, which by itself helps improve “Flora & Fauna” and “Habitat & Food”, even if marginally in the short-term. Finally, “Place & Space” improve as well, further boosting health and wellbeing and fostering engagement and identity within the local community, effects of which feed back to the beginning.
As interesting as this behavior may be, its impacts on emissions are less substantial than those of the eco-efficient appliances, highlighting the importance of both being deployed in tandem. Since steel is not present in the green spaces and gardens, and that the case study does not specify which are the types of food produced therein, nor if those are traditionally contained in steel cans and other steel containers, focus was given to the eco-efficient appliances when addressing the participation of steel in emissions. All other variables of the case study’s life cycle analysis were assumed unchanged, meaning eco-efficiency had no effect on the amount of steel content of each appliance. This choice was made due to the theoretical infinite number of possibilities by which eco-efficiency can be achieved by different manufacturers in different models of each appliance.
According to the results from Céron-Palma et al. [57
], replacing standard appliances with more eco-efficient ones reduced energy consumption by approximately 46%. Considering an average steel content of 60% per 140 kg refrigerator, 35% per 76 kg washing machine, and 46% per 37 kg air conditioning unit [80
], the calculations showed that steel’s participation in annual emissions per house was reduced by 32% on average, as a result of changing to eco-efficient appliances. More specifically from 4.90 to 3.35 kgCO2
eq/kg of steel (refrigerator), from 1.90 to 1.30 kgCO2
eq/kg of steel (washing machine), and from 84.67 to 57.76 kgCO2
eq/kg of steel (air conditioning unit).
These results grow in significance when keeping in mind the case study’s scope of 112,000 houses, resulting in the same 322 TJ to produce all the steel involved, generating 176.74 Mt of CO2eq emissions, instead of 259.06 Mt. In this case, even though the amount of steel per appliance and the energy used to produce it remained the same, steel’s contribution would not reside in its quantity, but in the type of steel and in how it is used in an appliance, for example, towards improving its eco-efficiency during the use phase.
Although this demand-side servitization initiative has minor effect on supply-side scale, the steelmakers’ challenge would be to decide on which type of steel to produce (e.g., alloys with better electrical conductivity) and how to ensure its optimal use in a product. Traditional use of steel in appliances revolves mostly around stainless or tool steels used in motors and structural segments, such as UNS S30400 and S43000. In eco-efficient appliances, steel use would tend to revolve more around electrical and tool steels similar to those present in electronics [73
], thus changing the alloying requirements of production.
After five years of the implementation of the CiViTaS project in the city of Burgos, a clear change in its citizens’ mobility behavior was noticed: It successfully stimulated approximately 10% of its population to transition from either walking or owning a private car towards using either more public transportation, bicycles, or lighter vehicles such as motorcycles [58
]. Considering bicycles and, notably, public transportation were provided as a service by the city for the population, and that these means of transportation are less—if at all—pollutant in comparison to cars, servitization has proven itself environmentally friendly once again.
Even considering an increase of 1% in the use of motorcycles and a 6% reduction in the amount of people who preferred to walk their commutes, emission results were very favorable, pointing towards a successful mobility solution proposition that positively affects urban environment. Keeping in mind that bicycles now have their dedicated lanes, and that buses and motorcycles contribute to reducing overall traffic in comparison to cars, this mobility solution also presents medium- to long-term sustainability benefits.
Using the criteria of sustainable urban metabolism, it is possible to identify that the study conducted by Diez et al. [58
] altered the city’s inputs and stocks, by affecting the composition of the city’s mass balance due to the different types of vehicles being used. Consequently, the flows related to mobility and transportation are rendered more efficient, still overshadowed; however, by the notable effects that takes place among the outputs. By changing the mobility matrix, not only do different materials become part of the urban system, but also different and more sustainable sources of energy gain traction: Less cars meant that gasoline and diesel gave way to buses’ biodiesel, for example.
With less of their income being used to own a car, “Wealth & Distribution” improved from the citizens’ perspective, as per the criteria of circles of sustainability, as seen in Figure 6
. Improving aspects of the political domain related to organization and communication would not only drive use and consumption towards a more sustainable behavior, but also help shift production and sourcing, thus promoting the exchange and transfer of more sustainable knowledge and goods. And even if improvements to technology and infrastructure would be minor, the increase in transportation services would require more jobs related to operation and maintenance instead of those related to the replacement of car parts and components.
The key contributions, nevertheless, are present in the ecology domain: Measures that help reduce traffic—which relate to “Construction & Settlement”—further help reduce emissions and contribute to citizens’ perception of place and space, due to better water and air quality, altogether boosting health and wellbeing in the culture domain as well. Therefore, this study configures a good example of sustainable urban mobility, well aligned with the idea of a sustainable urban metabolism.
Having changed which vehicles are used and the frequency of their usage, the study indirectly changed how steel is present in the city as well. Considering that cars, buses, bicycles, and motorcycles are built with different types of steel in different amounts—on average 900 kg, 6,000 kg, 6 kg, and 70 kg, respectively [85
]—not only do the total amounts of steel change, but also their participation in the emissions that occur as a consequence of their presence.
Although using more buses, bikes, and motorcycles caused the amount of steel and the consequent consumption of energy for its production to increase by approximately 18.23% (82.5% of which inside buses alone), having steel be a part of vehicles that are either less pollutant than cars or more efficient in terms of capacity or fuel caused steel’s participation in annual emissions to decrease by 29.6%, from 11.93 to 8.40 kgCO2eq/kg of steel.
This increase in steel presence associated with lower participation in emissions highlights the importance of defining when and where to use steel, especially considering that the types of steel used for buses—typically UNS S30400, S31600, S40900 and S43000 [73
]—are not necessarily considered specialty or complex alloys. It is to say that more steel can also be a solution, as long as it is used when and where necessary to support servitization and, further along, sustainability.