• Energy Research

Abstract The transition to full electromobility must be carefully evaluated, as large amounts of strategic metals will be required, for which there is presently little to no recovery or recycling (e.g. gold, silver, tantalum or cobalt). In this study, we perform a comprehensive metal assessment of two passenger cars (conventional and battery electric models) in terms of mass and thermodynamic rarity. Thermodynamic rarity is based on the property of exergy and is defined as “the amount of exergy resources needed to obtain a mineral commodity from average crustal concentration using the best available technology” (measured in kJ). Thus, the thermodynamic rarity approach assigns a greater exergetic value to scarce (understood as having a relative low average crustal concentration) and difficult-to-extract minerals. Of the 60 metals analyzed, almost 50 metals have been identified within the studied cars, representing 800 (conventional) and 1,200 kg (battery electric), showcasing the fact that a car constitutes a “road mine”. Furthermore, given that the technology behind battery electric cars is in development, three generations of Li-ion batteries were analyzed to study the effect on resource use of a metal changing composition over time. Albeit the battery modules of the three generations present a similar mass content (approximately 70 kgs), the thermodynamic rarity decreases from 275 to 100 Gigajoules, due to the reduced proportion of cobalt, which is by far the most exergetic metal within the battery. Additionally, with the thermodynamic rarity approach, the most exergy intensive parts within a battery electric car have been identified – the high-voltage battery modules, the electric drive, the power module, the charger, the electrical air conditioning compressor and the electromechanical brake servo – providing an indicator facilitating proactive mid- to long-term ecodesign measures and recycling strategies.

Moving towards a low-carbon economy will imply a considerable increase in the deployment of green technologies, which will in turn increase the demand of certain raw materials. In this paper, the material requirements for 2050 scenarios are assessed in terms of exergy to analyze the impact in natural resources in each scenario and identify which technologies are going to demand more resources. Renewable energy technologies are more mineral intensive than current energy sources. Using the International Energy Agency scenarios, from 2025 to 2050, total raw material demand is going to increase by 30%, being the transport sector the one that experiences the highest increase. Aluminum, iron, copper and potassium are those elements that present a higher share of the material needs for green technologies. Besides, there are five elements that experience at least a six-fold increase in demand in that period: cobalt, lithium, magnesium, titanium and zinc. Comparing those results with Greenpeace's AE [R] scenario, which considers a 100% renewable supply by 2050, this increase is even higher. Therefore, avoiding the dependency on fossil fuels will imply to accept the dependency on raw materials.

SummaryThe changing material composition of cars represents a challenge for future recycling of end‐of‐life vehicles (ELVs). Particularly, as current recycling targets are based solely on mass, critical metals increasingly used in cars might be lost during recycling processes, due to their small mass compared to bulk metals such as Fe and Al. We investigate a complementary indicator to material value in passenger vehicles based on exergy. The indicator is called thermodynamic rarity and represents the exergy cost (GJ) needed for producing a given material from bare rock to the market. According to our results, the thermodynamic rarity of critical metals used in cars, in most cases, supersedes that of the bulk metals that are the current focus of ELV recycling. While Fe, Al, and Cu account for more than 90% of the car's metal content, they only represent 60% of the total rarity of a car. In contrast, while Mo, Co, Nb, and Ni account for less than 1% of the car's metal content, their contribution to the car's rarity is larger than 7%. Rarity increases with the electrification level due to the greater amount of critical metals used; specifically, due to an increased use of (1) Al alloys are mainly used in the car's body‐in‐white of electric cars for light‐weighting purposes, (2) Cu in car electronics, and (3) Co, Li, Ni, and rare earth metals (La, Nd, and Pr) in Li‐ion and NiMH batteries.

A conventional passenger car demands almost 50 different types of metals, along other raw materials. Some of these metals, such as tantalum, indium, niobium or rare earths elements, are considered critical by the European Commission and many other institutions. Additionally, their functional recycling is practically absent. The transition to fully electric vehicles will require more electrical and electronic devices, motors and batteries, that will need an increasing amount of critical metals. A methodology has been developed to identify strategic elements for the automobile sector. This approach defines a variable called Strategic Metal Index (SMI) which is calculated for each metal. This index is the result of combining the following parameters: (1) Automobile sector demand with respect to world production; (2) known resources compared to total cumulative demand and (3) Supply risk. The index has been applied to 50 metals used by different types of vehicle powertrains. The assessment covers metal demand from 2018 to 2050 according to vehicle sales projections. Using this approach, the most strategic elements for the automobile manufacturing sector are Ni, Li and Co (used in batteries), Nd and Dy (permanent magnets), Tb (lighting and fuel injectors), Sb, Bi and and B (steel alloys, paintings), Au and Ag (electronics), In (screens) and Te (steel alloys, electronics). The search for substitutes, implementation of eco-design measures and the increase of the functional recyclability of these elements should be strongly encouraged in the sector.

Using a thermodynamic approach, this paper identifies the most critical parts of a car, considering their composition. A total of 11 car parts that contain valuable and scarce materials have been selected using thermodynamic rarity, an indicator that helps assess elements and minerals in exergy terms according to their relative scarcity in the crust and the energy required to extract and refine them. A recyclability analysis using a product-centric approach was then undertaken using dedicated software, HSC Chemistry. To that end, the dismantling of these car parts into three main fractions was performed. Each car part was divided into non-ferrous, steel, and aluminum flows. A general metallurgical process was developed and simulated for each flow, including all the required equipment to extract most of the minor but valuable metals. Of the 11 parts, only 7 have a recyclability potential higher than 85%. By treating these selected car parts appropriately, the raw materials’ value recovered from the car can increase by 6%. The approach used in this paper can help provide guidelines to improve the eco-design of cars and can also be applied to other sectors. Ultimately, this paper uniquely introduces simulation-based thermodynamic rarity analysis for thermodynamic based product “design for recycling”.

Light-duty vehicles are increasingly incorporating plastic materials to reduce production costs and achieve lightweight designs. On average, a conventional car utilizes over 200 kg of plastic, comprising more than 23 different types, which often present challenges for recycling due to their incompatibility. Consequently, the focus on plastic recycling in end-of-life vehicles has intensified. This study aims to analyze critical car parts based on the plastics used, employing a novel thermodynamic approach that examines the embodied exergy (EE) of different plastics. Six vehicles from various segments, years, and equipment levels were assessed to understand their plastic compositions. The findings reveal that, on average, a vehicle contains 222 kg of plastic, accounting for 17.7% of its total weight. Among these plastics, 47.5% (105 kg) are utilized in car parts weighing over 1 kg, with plastics comprising over 80% of the part’s weight. The identified critical car parts include the front door trim panel, front and rear covers, fuel tank, floor covering, front lighting, dashboard, rear door trim panel, plastic front end, backrest pad, door trim panel pocket, plastic foam rear seat, rear lighting, window guide, molded headliner, bulkhead sound insulation, foam seat part, and wheel trim. Regarding their contribution to EE, the plastics with the highest shares are polypropylene—PP (24.5%), polypropylene and ethylene blends—E/P (20.3%), and polyurethane- PU (15.3%). Understanding the criticality of these car parts and their associated plastics enables targeted efforts in design, material selection, and end-of-life management to enhance recycling and promote circularity within the automotive industry.

Flat roofs present a large potential of suitable areas for installation of PV (photovoltaic) plants. Flat roof PV installations have the advantage of being able to be optimally positioned with support structures, and the inclination angle can be adjusted. Due to the important technological development existing in the PV sector, there are different PV technologies in the market, whose energy and economic features substantially differ. This paper describes some useful parameters to assess the technology and distribution of modules to be installed in flat roofs and terraces of buildings. The effect on the energy parameters of the modules tilt and disposition is analyzed in a case study, considering different technologies.