the Netherlands, France, and Spain, but also upper and lower middle-income countries, such as China, India and Türkiye.

Third we set out an analytical framework to identify countries that could be best placed to help diversify a specific product market. For example, although the global production of glass mirrors, a key component in the solar PV value chain, is highly concentrated in a single country, several countries that could be well positioned to expand their export activity in this product include Lithuania, Poland, India, Türkiye and the Netherlands. These countries already have a reasonably strong track record of exports, high recent growth rates, and production capabilities that are closely aligned with this product. This framework builds on the work of Mealy and Teytelboym (2022) that applied a similar approach to products that exhibit environmental benefits. Moreover, it contributes to the broader literature drawing on data-driven approaches to inform green industrial policy and economic development strategies (Montresor and Quatraro, 2019; Balland et al., 2019).

Our work is not without limitations. First, while our product mapping of value chains associated with decarbonization technologies relies on the 6-digit of the Harmonized System (HS), the most detailed internationally standardized product classification, products may have dual use. This means that a product may have additional applications or purposes beyond those relevant to the value chains of decarbonization technologies. Second, although the product classification of the 6-digit HS is remarkably detailed, a HS 6-digit code is not a single product but an average of differentiated product varieties. As a result, our product definition may be too broad to clearly identify products associated with decarbonization technologies. As it is currently not possible to determine what proportion of trade in each product relates primarily to decarbonization technology usage, the total product export volumes shown in this paper should be considered as an upper bound. The collection of more detailed input, output or supply chain data that is comparable across countries would allow for more accurate depictions of these global value chains. Finally, lags in trade data should also be kept in mind as recent developments and/or interventions are not accounted for.

# 2. Results

## 2.1 Mapping global value chains of key decarbonization technologies

To analyze trade patterns in the global value chains for solar PV, wind turbines and EVs, we collated a new dataset of end products, subcomponents, processed and raw materials classified under the 6-digit HS. The 6-digit HS is a standardized classification of traded products used by customs authorities around the world. It is also the most granular classification that is comparable across almost all countries and over time (see the Methods section for more detail). Figure 1 shows an illustration of the solar PV value chain, with example products listed. Due to the challenges of classifying such products under the 6-digit HS (IISD, 2020), our dataset is not exhaustive but intended to focus on the key identifiable elements of each value chain.<sup>2</sup> As EV production includes products that are also used in internal combustion engine (ICE) vehicles, we construct two sets of value chain products: one more broadly defined and one more narrowly defined. The broader set includes HS products associated with the wider vehicle manufacturing value chain, e.g., products used in either ICE vehicles or EVs. The narrower EV value chain only considers products that relate specifically to EVs, e.g., battery end products and components and the assembled EV end product.

> 2 All products included in our dataset were subject to a series of independent evaluations by selected industry specialists (see Methods section 4.1 for further information and Table SI 6 for a list of the included products).

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