Abstract: Auctions are increasingly being used to allocate emissions allowances (“permits”) for cap and trade and common-pool resource management programs. These auctions create thick markets that can provide important information about changes in current market conditions. This paper reports a laboratory experiment in which half of the bidders experienced unannounced increases in their willingness to pay for permits. The focus is on the extent to which the predicted price increase due to the demand shift is reflected in sales prices under alternative auction formats. Price tracking is good for uniform-price, sealed-bid auctions and for multiround clock auctions, with or without end-of-round information about excess demand. Price inertia is observed for “pay as bid” (discriminatory) auctions, especially for a continuous discriminatory format in which bids could be changed at will during a prespecified time window, in part because “sniping” in the final moments blocked the full effect of the demand shock.

Abstract: We use a stochastic dynamic framework to compare price collars (price ceilings and floors) in a cap-and-trade system. Sources of uncertainty include shocks to baseline emissions, affecting corresponding abatement costs, and shocks to the supply of offsets. We consider a continuum between soft collars, which have a limited volume of additional emission allowances (a reserve) available at the price ceiling, and hard collars, which provide an unlimited supply of additional allowances, thereby preventing allowance prices from exceeding the price ceiling. For all cases considered, we set the price floors and ceiling such that the expected cumulative emissions net of offsets are equal to the cumulative allowances. Consequently, increasing the size of the allowance reserve requires higher price ceilings and floors, and a lower probability of reaching the ceiling. Across most parameter values examined, we find that increasing the size of the allowance reserve leads to lower expected net present values of compliance costs, although the differences are not large. However, when offset supply shocks are highly persistent and exhibit strong (negative) correlation with baseline emission shocks, hard collars deliver noticeably lower expected costs, though with a wider range of emission outcomes than the soft collars.