Policymakers in various countries often determine roadmaps, a sequence of intermediate goals to achieve their long-term renewable energy objectives. We study the influence of roadmaps on regulatory decisions and market functioning using laboratory experiments. We simulate a stylized electricity market with two generation technologies (a renewable “green” technology and a thermal source) whose share of renewable generation must increase over a 40-year period. Investments in thermal capacity are driven by subsidies and profitability, while green capacity investments solely depend on subsidies. Participants act as regulators and decide each year how many MWs of green and thermal capacity to subsidize while managing the trade-off between blackout risk, cost for customers and subsidies. We manipulate the presence and the time granularity of roadmaps.

We find that roadmaps impact regulatory decisions and the resulting subsidies, but not the likelihood of achieving the long-term goals, illustrating that a given target can be reached by different trajectories with different costs. Therefore, policymakers should carefully consider the choice of intermediate objectives that impact paths toward greener energy in terms of trade-offs between governmental subsidies and market forces.

各国的政策制定者通常会确定路线图，即实现其长期可再生能源目标的一系列中间目标。我们使用实验室实验研究路线图对监管决策和市场运作的影响。我们使用两种发电技术（一种可再生“绿色”技术和一种热源）模拟一个程式化的电力市场，其可再生能源发电的份额必须在 40 年内增加。热能投资由补贴和盈利能力驱动，而绿色产能投资完全依赖补贴。参与者充当监管者，决定每年补贴多少兆瓦的绿色和热容量，同时管理停电风险、客户成本和补贴之间的权衡。我们操纵路线图的存在和时间粒度。

我们发现路线图会影响监管决策和由此产生的补贴，但不会影响实现长期目标的可能性，这表明可以通过不同的轨迹以不同的成本实现给定的目标。因此，政策制定者应根据政府补贴和市场力量之间的权衡，仔细考虑影响绿色能源路径的中间目标的选择。