Ratcheting Up Policy Effort to Sustain Technological Growth: The Case of Onshore Wind in Germany

Decarbonizing energy systems is central to achieving climate change mitigation goals, requiring the rapid and sustained growth of renewables at different stages of growth. For example, in 2022, the German government introduced new laws to triple the speed of both mature renewables such as onshore wind power, and more nascent technologies such as offshore wind power. Given limited government budgets and capacities, it is essential to know what type and level of effort to extend to technologies at different stages of growth, but there is no consensus on policy recommendations in the literature. Some argue that policy effort should be highest in early stages of growth when technology costs are high, and subsequently decrease as costs decrease. Others argue that sustained policy effort is required over time as new challenges to technology diffusion, such as system integration or social acceptance, emerge. To address this gap, we examine the evolution of policy effort throughout the different growth stages of onshore wind power in Germany from 1974 to 2024. This is an ideally suited technology-country pair as onshore wind power has surpassed early stages of growth in the German context, and there is clear evidence for sustained policy interest in its expansion given the latest renewables targets. We operationalise policy effort using two metrics: (1) policy density (the number and types of policies) and (2) levels of financial support (including public research and development (R&D) funding and feed-in remuneration for onshore wind power). By mapping these measures to annual capacity additions of onshore wind power, we analyze how policy effort and onshore wind deployment have evolved over time and in relation to one another. We find that policy density (both in total amount of policies and in types of policies) has increased over time. Significant changes in policy density coincide with turning points in annual capacity additions; for example, a decrease in capacity additions between 2004-2007 was followed by additional policies mainly focused on grid expansion; and another slow-down in 2017 was met with regulatory and institutional amendments, as well as additional policies to support public acceptance. We find that the amount of total financial support for onshore wind has also increased over time. Relative to deployment, public research funding decreased since the 1980s but slightly rebounded around 2007/2008; and feed-in remuneration per kWh power has decreased since 2000, stabilized between 2007 and 2017, and recently shown a slight increase. These results underscore the need for sustained policy effort beyond early deployment stages to address new barriers arising with technological growth. The evolution of Germany's policy mix highlights the interplay of policy and technology feedbacks, with increasing amount and variation in types of policies indicating an overall "ratcheting up" of effort. Financial support trends further suggest that while support relative to deployment may decrease with maturity, renewed increases may be required to sustain growth. Future research should extend this exploratory analysis to other technologies and countries, and may ultimately explore policy effort likely required for renewables deployment in line with climate scenarios.