We develop an equilibrium model of emissions permit trading in the presence of fixed and proportional trading costs in which the permit price and firms' participation in and extent of trading are endogenously determined. We analyze the sensitivity of the equilibrium to changes in the trading costs and firms' allocations, and characterize situations where the trading costs depress or raise permit prices relative to frictionless market conditions. We calibrate our model to annual transaction data in Phase II of the EU ETS (2008–2012) and find that trading costs in the order of 10 k€ per annum plus 1 € per permit traded substantially reduce discrepancies between observations and theoretical predictions for firms’ behavior (e.g. autarkic compliance for small and/or long firms). Our simulations suggest that ignoring trading costs leads to an underestimation of the price impacts of supply-curbing policies, this difference varying with the incidence on firms.

在固定和成比例的交易成本存在的情况下，我们建立了排放权交易的均衡模型，在此模型中，内在确定了许可证价格和企业的参与程度以及交易范围。我们分析了均衡对交易成本和企业分配变化的敏感性，并描述了交易成本相对于无摩擦市场条件压低或提高许可价格的情况。我们根据欧盟排放交易体系第二阶段（2008-2012年）的年度交易数据对模型进行了校准，发现每年交易成本大约为1万欧元加上每许可1欧元，可大大减少企业的观察与理论预测之间的差异。行为（例如，小型和/或长期公司的自律遵守）。