“…Portfolios or mixes of policy instruments respond to a diverse set of technical, political, institutional and economic uncertainties and constraints (Flanagan et al, 2011;Grubb et al, 2017). A comprehensive mix of policy instruments may include technology-push, market-pull, and systemic instruments (which address innovation system failures such as weak actor networks) (Costantini et al, 2017), as well as instruments of different types (e.g., regulation, market-based, and RD&D), and both technology-neutral and technology-specific instruments (Rosenow et al, 2017). Durability and stability in the policy environment provide clear signals to innovators and reduce regulatory risk (Barradale, 2009;Löfgren et al, 2008;Johnstone, 2011).…”