In 2016, the Regulatory Assistance Project approached Cambridge Econometrics about building a new macroeconomic modelling tool for India. The rationale for the model was simple: India needed to reduce its greenhouse gas emissions, but much of the policy to do so is set at the state level. A model that could identify the impacts of policies to boost state-level sustainable growth was therefore required.

Years later, the outputs of this work are presented in the book Economy-Wide Assessment of Regional Policies in India, edited by professor Kakali Mukhopadhyay. The book covers a range of topics relating to sustainable economic development in India, always with a focus on realistic (i.e., feasible) policy at the state level.

The model that was built came to be known as E3-India — “E3” for energy-environment-economy. It was developed by experts at Cambridge Econometrics, Professor Mukhopadhyay and former RAP colleagues Ranjit Bharvirkar and Surabhi Joshi. Without this collaboration, it is unlikely the model would have advanced to its present state.

The foundations of the model follow the Cambridge tradition, drawing on the demand-driven framework originally developed by Michal Kalecki and John Maynard Keynes. This approach provides several advantages over the more common equilibrium approach to modelling; it does not make assumptions about perfect information, rational behaviour or frictionless markets. In addition, it models labour markets, including involuntary unemployment — matters of particular importance to policymakers.

This demand-driven approach requires that behavioural parameters be informed by econometrics — that is, it requires, among other things, time-series historical data. With the model disaggregating India’s economy into both states and economic sectors, a substantial exercise in data collection and processing was required. Professor Mukhopadhyay led this herculean effort, yielding a tool that researchers today can download and use free of charge.

Another important feature of the model is its tight integration of energy consumption and greenhouse gas emissions within the wider economy. The model ensures consistency between physical and economic measures of energy consumption and prices — something that is critical for effectively assessing sustainability. The power sector, which will play a crucial role in decarbonising India’s economy, is modelled in additional detail using an advanced framework developed by Jean-Francois Mercure. This allows the user to test policies such as feed-in tariffs, renewable subsidies and coal phaseouts, along with the standard energy and carbon tax policies that other models typically examine.

Each chapter of the book is dedicated to a different sector of the economy. A set of scenarios is used to explore different possible outcomes by implementing combinations of policies. The demand-driven nature of the model allows the analysis to start from a position in which the Indian economy has been set back by COVID-19; many of the scenarios look at ways to restore jobs and prosperity.

Eleven authors, experts in their respective fields, were involved in the production of the book. They put the E3 model to rigorous use, testing its capabilities and performance, and with it have revealed some important truths about the Indian economy and good news about its ability to transform itself into the sustainable, low-carbon powerhouse that it aspires to be.

The book is by no means the end of the E3-India project; in many ways, it is just the beginning. E3-India is a tool that policymakers can use for many years to come as they embark on the journey of promoting sustainable development. The model will continue to be updated. We encourage readers of the book to work with the model themselves, to challenge its conclusions and to examine other scenarios, all with the aim of developing public policies dedicated to improving the long-term welfare of Indian society and the environment. If India is to contribute to meeting global climate targets, much work remains to be done.