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As with other commodity markets, markets for trading pollution permits have not been immune to market power concerns. In this paper, I survey the existing literature on market power in permit trading but also contribute with some new results and ideas. I start the survey with Hahn’s (1984) dominant-firm (static) model that I then extend to the case in which there are two or more strategic firms that may also strategically interact in the output market, to the case in which current permits can be stored for future use (as in most existing and proposed market designs), to the possibility of collusive behavior, and to the case in which permits are auctioned off instead of allocated for free to firms. I finish the paper with a review of empirical evidence on market power, if any, with particular attention to the U.S. sulfur market and the Southern California NOx market., Massachusetts Institute of Technology. Center for Energy and Environmental Policy Research.

As with other commodity markets, markets for trading pollution permits have not been immune to market power concerns. In this paper, I survey the existing literature on market power in permit trading but also contribute with some new results and ideas. I start the survey with Hahn’s (1984) dominant-firm (static) model that I then extend to the case in which there are two or more strategic firms that may also strategically interact in the output market, to the case in which current permits can be stored for future use (as in most existing and proposed market designs), to the possibility of collusive behavior, and to the case in which permits are auctioned off instead of allocated for free to firms. I finish the paper with a review of empirical evidence on market power, if any, with particular attention to the U.S. sulfur market and the Southern California NOx market., Massachusetts Institute of Technology. Center for Energy and Environmental Policy Research.

This paper extends Weitzman's (1974) "Prices vs. Quantities" to allow for incomplete enforcement. Whether the regulator uses prices (e.g., taxes) or quantities (e.g., tradeable quotas), a first-best design is always inefficient in the presence of incomplete enforcement. A second-best design that incorporates incomplete enforcement, and where cost and benefit curves are known with certainty, can be implemented equally well with either instrument. If benefit and cost curves are uncertain, however, a quantity instrument performs better than a price instrument. In fact, if the slopes of the marginal cost and marginal benefit curves are equal, quantities are always preferred over prices. Results are consistent to alternative enforcement policies., Supported by the MIT Center for Energy and Environmental Policy Research.

I study the optimal design of marketable permit systems to regulate various pollutants (e.g. air pollution in urban areas) when the regulator lives in a real world of imperfect information and incomplete enforcement. I show that the regulator should have pollution markets integrated through optimal exchange rates when the marginal abatement cost curves in the different markets are steeper than the marginal benefit curves; otherwise he should keep markets separated. I also find that incomplete enforcement reduces the advantage of market integration., Supported by the MIT Center for Energy and Environmental Policy Research.

Despite growing interest in the use of emissions trading for pollution control, empirical evidence for this regulatory instrument has been confined to a few experiences in the United States. This paper broadens the empirical base by examining the "Emission-Offsets Trading Program" that has been in place since 1992 to control airborne particulate emissions in Santiago, Chile. While the program is doing well from an environmental perspective, due in part to the price-based introduction of natural gas, the market is performing poorly because of high transaction costs, uncertainty, and poor enforcement. However, the scarcity rents created by allocating grandfathered emission rights to incumbents have proved to be a very effective tool for completing the emissions inventory., Supported by the MIT Center for Energy and Environmental Policy Research.

A tradeable permits market is said to be efficient when all affected firms trade permits until their marginal costs equal the market price. Detailed firm-level data are generally required to perform such an efficiency test, yet such information is rarely available. If firms face a declining target, however, and are allowed to bank permits, as has occured recently, aggregated data such as the evolution of the permits bank is sufficient to test for either less than optimal market participation or the exercise of market power. An application to the U.S. sulfur dioxide emission permits market is provided., Supported by the MIT Center for Energy and Environmental Policy Research.

This paper provides an empirical evaluation of the efficiency of allowance banking (i.e., abating more in early periods in order to abate less in later periods) in the nationwide market for sulfur dioxide (SO2) emission allowances that was created by the U.S. Acid Rain Program. We develop a model of efficient banking, select appropriate parameter values, and evaluate the efficiency of observed temporal pattern of abatement based on aggregate data from the first eight years of the Acid Rain Program. Contrary to the general opinion that banking in this program has been excessive, we find that it has been reasonably efficient. We also show that this optimal banking program is robust to the errors in expectation that characterized the early years of this program; however, this property is due to design features that are unique to the U.S. Acid Rain Program., Supported by the MIT Center for Energy and Environmental Policy Research.

Despite growing interest in the use of emissions trading for pollution control, empirical evidence for this regulatory instrument has been confined to a few experiences in the United States. This paper broadens the empirical base by examining the "Emission-Offsets Trading Program" that has been in place since 1992 to control airborne particulate emissions in Santiago, Chile. While the program is doing well from an environmental perspective, due in part to the price-based introduction of natural gas, the market is performing poorly because of high transaction costs, uncertainty, and poor enforcement. However, the scarcity rents created by allocating grandfathered emission rights to incumbents have proved to be a very effective tool for completing the emissions inventory., Supported by the MIT Center for Energy and Environmental Policy Research.

We consider an infinitely-repeated oligopoly in which at each period firms not only serve the spot market by either competing in prices or quantities but also have the opportunity to trade forward contracts. Contrary to the pro-competitive results of finite-horizon models, we find that the possibility of forward trading allows firms to sustain collusive profits that otherwise would not be possible. The result holds both for price and quantity competition and follows because (collusive) contracting of future sales is more effective in deterring deviations from the collusive plan than in inducing the previously identified pro-competitive effects.

I study the design of environmental policies for a regulator that has incomplete information on firms' emissions and costs of production and abatement (e.g., air pollution in cities with numerous small polluting sources). Because of incomplete information on emissions, there is no policy that can implement the first-best. Since the regulator can observe firms' abatement technologies, however, it is possible to design a quasi-emissions trading program based on this information and show that it can provide higher welfare than command-and-control regulation such as technology or emission standards. I then empirically examine this claim using evidence from a particulate quasi-emissions trading program in Santiago, Chile., Supported by the MIT Center for Energy and Environmental Policy Research.

We consider an infinitely-repeated oligopoly in which at each period firms not only serve the spot market by either competing in prices or quantities but also have the opportunity to trade forward contracts. Contrary to the pro-competitive results of finite-horizon models, we find that the possibility of forward trading allows firms to sustain collusive profits that otherwise would not be possible. The result holds both for price and quantity competition and follows because (collusive) contracting of future sales is more effective in deterring deviations from the collusive plan than in inducing the previously identified pro-competitive effects.

In this paper we explore the welfare implications of voluntary compliance within an emissions trading program and derive optimal permits allocations to affected and opti-in sources when the environmental regulator has incomplete information on individual unrestricted emissions and control costs. The regulator faces a trade-off between production efficiency (minimization of control costs) and information rent extraction (reduction of excess permits allocated to opt-in sources). The first-best equilibrium can be attained if the regulator can freely allocate permits to affected and opt-in sources; otherwise a second-best equilibrium is implemented. The latter is sensitive to uncertainty in control costs and benefits, Supported by the National Oceanic and Atmospheric Administration through an award the the MIT Center for Energy and Environmental Policy Research.

I study the design of environmental policies for a regulator that has incomplete information on firms' emissions and costs of production and abatement (e.g., air pollution in cities with numerous small polluting sources). Because of incomplete information on emissions, there is no policy that can implement the first-best. Since the regulator can observe firms' abatement technologies, however, it is possible to design a quasi-emissions trading program based on this information and show that it can provide higher welfare than command-and-control regulation such as technology or emission standards. I then empirically examine this claim using evidence from a particulate quasi-emissions trading program in Santiago, Chile., Supported by the MIT Center for Energy and Environmental Policy Research.

We consider an infinitely-repeated oligopoly in which at each period firms not only serve the spot market by either competing in prices or quantities but also have the opportunity to trade forward contracts. Contrary to the pro-competitive results of finite-horizon models, we find that the possibility of forward trading allows firms to sustain collusive profits that otherwise would not be possible. The result holds both for price and quantity competition and follows because (collusive) contracting of future sales is more effective in deterring deviations from the collusive plan than in inducing the previously identified pro-competitive effects.

This paper provides an empirical evaluation of the temporal efficiency of the U.S. Acid Rain Program, which implemented a nationwide market for trading and banking sulfur dioxide (SO2) emission allowances. We first develop a model of efficient banking and select appropriate parameter values. Then, we use aggregate data from the first seven years of the Acid Rain Program, to assess the temporal efficiency of the observed banking behavior. We find that banking has been surprisingly efficient and we discuss why this finding disagrees with the common perception of excessive banking in this program.

The low price of allowances has been a frequently noted featured of the implementation of the sulfur dioxide emissions market of the U.S. Acid Rain Program. This paper presents theoretical and numerical analyses that explain the gap between expected and observed allowance prices. The main contributing factors appear to be expectation errors augmented by the presence of irreversible investments., Supported by the MIT Center for Energy and Environmental Policy Research.

We analyze oligopolistic exhaustible-resource depletion when firms can trade forward contracts on deliveries, a market structure prevalent in many resource commodity markets. We find that this organization of trade has substantial implications for resource depletion. As firms' interactions become infinitely frequent, resource stocks become fully contracted and the symmetric oligopolistic equilibrium converges to the perfectly competitive Hotelling (1931) outcome. Asymmetries in stock holdings allow firms to partially escape the procompetitive effect of contracting: a large stock provides commitment to leave a fraction of the stock uncontracted. In contrast, a small stock provides commitment to sell early, during the most profitable part of the equilibrium.

Efficient regulation of the commons requires information about the regulated firms that is rarely available to regulators (e.g., cost of pollution abatement). Different mechanisms have been proposed for inducing firms to reveal their private information but for reasons I discuss in the paper, I find these mechanisms of limited use. I propose a much simpler mechanism that implements the first-best for any number of firms: a uniform price sealed-bid auction of an endogenous number of (transferable) licenses with a fraction of the auction revenues given back to firms. Paybacks, which decrease with the number of firms, are such that truth-telling is a dominant strategy regardless of whether firms behave non-cooperatively or collusively.

This paper presents an analysis of the reduction in SO2 emissions by electric utilities between 1985 and 1993. We find that emissions have been reduced for reasons largely unrelated to the emission reduction mandate incorporated in Title IV of the 1990 Clean Air Act Amendments. The principal reason appears to be the change in the economics of coal choice that has resulted from the remarkable decline in rail rates for low sulfur western coal delivered to higher sulfur coal-fired plants in the Midwest. We conclude that allowance prices are lower than expected because less sulfur must be removed to meet the Title IV caps on aggregate SO2 emissions., Supported by a grant from the National Acidic Precipitation Assessment Program of the US Government, and the Catholic University of Chile.

In this paper, we investigate the effect of market power on the equilibrium path of an emission permits market in which firms can bank current permits for use in later periods. In particular, we study the market equilibrium for a large (potentially dominant) firm and a competitive fringe with rational expectations. We characterize the equilibrium solution for different permits allocations. We find, for example, that if the large firm enjoys a dominant position in the after-banking market, this position gets extended to the market during the banking period regardless of the allocation of the stock (bank) of permits.

I explore the advantages of tradable emission permits over uniform emission standards when the regulator has incomplete information on firms₂ emissions and costs of production and abatement (e.g., air pollution in large cities). Because the regulator only observes each firm₂s abatement technology but neither its emissions nor its output, there are cases in which standards can lead to lower emissions and, hence, welfare dominate permits. I then empirically examine these issues using evidence from a particulate permits market in Santiago, Chile.

We consider a market for storable pollution permits in which a large agent and a fringe of small agents gradually consume a stock of permits until they reach a long-run emissions limit. The subgame-perfect equilibrium exhibits no market power unless the large agent's share of the initial stock of permits exceeds a critical level. We then apply our theoretical results to a global market for carbon dioxide emissions and the existing US market for sulfur dioxide emissions. We characterize competitive permit allocation profiles for the carbon market and find no evidence of market power in the sulfur market.

I study the advantages of pollution permit markets over traditional standard regulations when the regulator has incomplete information on firms₂ emissions and costs of production and abatement (e.g., air pollution in large cities). Because the regulator only observes each firm₂s abatement technology but neither its emissions nor its output, there are cases in which standards can lead to lower emissions and, hence, welfare dominate permits. If permits are optimally combined with standards, in many cases this hybrid policy converges to the permits-alone policy but (almost) never to the standards-alone policy.

This paper extends Weitzman's (1974) "Prices vs. Quantities" to allow for incomplete enforcement. Whether the regulator uses prices (e.g., taxes) or quantities (e.g., tradeable quotas), a first-best design is always inefficient in the presence of incomplete enforcement. A second-best design that incorporates incomplete enforcement, and where cost and benefit curves are known with certainty, can be implemented equally well with either instrument. If benefit and cost curves are uncertain, however, a quantity instrument performs better than a price instrument. In fact, if the slopes of the marginal cost and marginal benefit curves are equal, quantities are always preferred over prices. Results are consistent to alternative enforcement policies., Supported by the MIT Center for Energy and Environmental Policy Research.

Following the structure of many commodity markets, we consider a reduced number of large firms and a competitive fringe of many small suppliers choosing quantities in an infinitehorizon setting subject to demand shocks. We show that a collusive agreement among the large firms may not only bring an output contraction but also an output expansion (relative to the non-collusive output level). The latter occurs during booms, when the fringe's market share is more important, and is due to the strategic substitutability of quantities (we will never observe an output expanding collusion in a price setting game). In addition and depending on the fringe's market share the time at which collusion is most difficult to sustain can be either at booms or recessions.

This paper presents an analysis of the reduction in SO2 emissions by electric utilities between 1985 and 1993. We find that emissions have been reduced for reasons largely unrelated to the emission reduction mandate incorporated in Title IV of the 1990 Clean Air Act Amendments. The principal reason appears to be the change in the economics of coal choice that has resulted from the remarkable decline in rail rates for low sulfur western coal delivered to higher sulfur coal-fired plants in the Midwest. We conclude that allowance prices are lower than expected because less sulfur must be removed to meet the Title IV caps on aggregate SO2 emissions., Supported by a grant from the National Acidic Precipitation Assessment Program of the US Government, and the Catholic University of Chile.

We analyze oligopolistic exhaustible-resource depletion when firms can trade forward contracts on deliveries, a market structure prevalent in many resource commodity markets. We find that this organization of trade has substantial implications for resource depletion. As firms' interactions become infinitely frequent, resource stocks become fully contracted and the symmetric oligopolistic equilibrium converges to the perfectly competitive Hotelling (1931) outcome. Asymmetries in stock holdings allow firms to partially escape the procompetitive effect of contracting: a large stock provides commitment to leave a fraction of the stock uncontracted. In contrast, a small stock provides commitment to sell early, during the most profitable part of the equilibrium.

A tradeable permits market is said to be efficient when all affected firms trade permits until their marginal costs equal the market price. Detailed firm-level data are generally required to perform such an efficiency test, yet such information is rarely available. If firms face a declining target, however, and are allowed to bank permits, as has occured recently, aggregated data such as the evolution of the permits bank is sufficient to test for either less than optimal market participation or the exercise of market power. An application to the U.S. sulfur dioxide emission permits market is provided., Supported by the MIT Center for Energy and Environmental Policy Research.

We consider a market for storable pollution permits in which a large agent and a fringe of small agents gradually consume a stock of permits until they reach a long-run emissions limit. The subgame-perfect equilibrium exhibits no market power unless the large agent's share of the initial stock of permits exceeds a critical level. We then apply our theoretical results to a global market for carbon dioxide emissions and the existing US market for sulfur dioxide emissions. We characterize competitive permit allocation profiles for the carbon market and find no evidence of market power in the sulfur market.

In this paper we explore the practical and welfare implications of a system of voluntary compliance within a market-based environmental regulation. The Substitution Provision of the SO2 emissions trading program allows the owner or operator of an affected electric utility unit to voluntarily designate a non-affected electric unit to become subject to all compliance requirements of affected units and to receive SO2 tradeable emission permits (allowances). We find that although the Substitution provision has had a rather small effect on the overall performance of the SO2 emissions trading program and on SO2 emissions reductions, there has been a significant participation, with more than half of the "affected" electric utilities using this voluntary option to reduce compliance costs. This provides further evidence to the notion that, in general, electric utilities are choosing cost-effective strategies to comply with SO2 limits. Consistent with that is our finding that transaction costs associated to the Substitution provision has been relatively low. In another result, we show that non-affected units have opted in, largely because their actual unrestricted emissions (i.e. emissions in the absence of regulation) are below their historic emissions and hence their allowance allocation. Other units have opted in because they have low marginal control costs, say, below allowance prices. While the latter effect reduce today's aggregate cost of compliance by shifting reduction from high cost affected units to low cost units (the flexibility effect), the first effect increases today's emissions and emissions in the future (the adverse selection effect). An ex post cost-benefit analysis suggests that the adverse selection effect dominates, in part because of low allowance prices. From an ex ante perspective however, we show that this result may not hold., Supported by the MIT Center for Energy and Environmental Policy Research.

We consider an infinitely-repeated oligopoly in which at each period firms not only serve the spot market by either competing in prices or quantities but also have the opportunity to trade forward contracts. Contrary to the pro-competitive results of finite-horizon models, we find that the possibility of forward trading allows firms to sustain collusive profits that otherwise would not be possible. The result holds both for price and quantity competition and follows because (collusive) contracting of future sales is more effective in deterring deviations from the collusive plan than in inducing the previously identified pro-competitive effects.

This paper provides an empirical evaluation of the efficiency of allowance banking (i.e., abating more in early periods in order to abate less in later periods) in the nationwide market for sulfur dioxide (SO2) emission allowances that was created by the U.S. Acid Rain Program. We develop a model of efficient banking, select appropriate parameter values, and evaluate the efficiency of observed temporal pattern of abatement based on aggregate data from the first eight years of the Acid Rain Program. Contrary to the general opinion that banking in this program has been excessive, we find that it has been reasonably efficient. We also show that this optimal banking program is robust to the errors in expectation that characterized the early years of this program; however, this property is due to design features that are unique to the U.S. Acid Rain Program., Supported by the MIT Center for Energy and Environmental Policy Research.

I explore the advantages of tradable emission permits over uniform emission standards when the regulator has incomplete information on firms₂ emissions and costs of production and abatement (e.g., air pollution in large cities). Because the regulator only observes each firm₂s abatement technology but neither its emissions nor its output, there are cases in which standards can lead to lower emissions and, hence, welfare dominate permits. I then empirically examine these issues using evidence from a particulate permits market in Santiago, Chile.

The U.S. acid rain program, Title IV of the 1990 Clean Air Act Amendments, is a pioneering experience in environmental regulation by setting a market for electric utility emissions of sulfur dioxide (SO2) and by including a voluntary compliance provision. Under the Substitution provision, non-affected electric utility units can voluntarily become subject to all compliance requirements of affected units and receive SO2 tradeable permits (allowances). This paper studies the welfare implications of this voluntary provision and tests the adverse selection hypothesis of voluntary programs. The results indicate that although this provision has had a rather small effect on the overall performance of the SO2 market, there has been a significant participation, mostly from units with counterfactual emissions (i.e. emissions in the absence of regulation) well below their allowance allocations, which suggests that SO2 emissions have been higher than otherwise. An ex post cost-benefit analysis shows that this adverse selection effect tend to dominate the flexibility effect of permitting shifts in emissions reductions from high-cost affected units to low-cost non-affected units. On the other hand, participation with the Substitution provision confirms that electric utilities are choosing cost-effective strategies to comply with SO2 limits and that transaction costs have been low., Supported by the MIT Center for Energy and Environmental Policy Research and Fondecyt-Chille Grant.

In this paper we explore the welfare implications of voluntary compliance within an emissions trading program and derive optimal permits allocations to affected and opti-in sources when the environmental regulator has incomplete information on individual unrestricted emissions and control costs. The regulator faces a trade-off between production efficiency (minimization of control costs) and information rent extraction (reduction of excess permits allocated to opt-in sources). The first-best equilibrium can be attained if the regulator can freely allocate permits to affected and opt-in sources; otherwise a second-best equilibrium is implemented. The latter is sensitive to uncertainty in control costs and benefits, Supported by the National Oceanic and Atmospheric Administration through an award the the MIT Center for Energy and Environmental Policy Research.

I study the advantages of pollution permit markets over traditional standard regulations when the regulator has incomplete information on firms₂ emissions and costs of production and abatement (e.g., air pollution in large cities). Because the regulator only observes each firm₂s abatement technology but neither its emissions nor its output, there are cases in which standards can lead to lower emissions and, hence, welfare dominate permits. If permits are optimally combined with standards, in many cases this hybrid policy converges to the permits-alone policy but (almost) never to the standards-alone policy.

The low price of allowances has been a frequently noted featured of the implementation of the sulfur dioxide emissions market of the U.S. Acid Rain Program. This paper presents theoretical and numerical analyses that explain the gap between expected and observed allowance prices. The main contributing factors appear to be expectation errors augmented by the presence of irreversible investments., Supported by the MIT Center for Energy and Environmental Policy Research.

I study the optimal design of marketable permit systems to regulate various pollutants (e.g. air pollution in urban areas) when the regulator lives in a real world of imperfect information and incomplete enforcement. I show that the regulator should have pollution markets integrated through optimal exchange rates when the marginal abatement cost curves in the different markets are steeper than the marginal benefit curves; otherwise he should keep markets separated. I also find that incomplete enforcement reduces the advantage of market integration., Supported by the MIT Center for Energy and Environmental Policy Research.

In this paper, we investigate the effect of market power on the equilibrium path of an emission permits market in which firms can bank current permits for use in later periods. In particular, we study the market equilibrium for a large (potentially dominant) firm and a competitive fringe with rational expectations. We characterize the equilibrium solution for different permits allocations. We find, for example, that if the large firm enjoys a dominant position in the after-banking market, this position gets extended to the market during the banking period regardless of the allocation of the stock (bank) of permits.

Efficient regulation of the commons requires information about the regulated firms that is rarely available to regulators (e.g., cost of pollution abatement). Different mechanisms have been proposed for inducing firms to reveal their private information but for reasons I discuss in the paper, I find these mechanisms of limited use. I propose a much simpler mechanism that implements the first-best for any number of firms: a uniform price sealed-bid auction of an endogenous number of (transferable) licenses with a fraction of the auction revenues given back to firms. Paybacks, which decrease with the number of firms, are such that truth-telling is a dominant strategy regardless of whether firms behave non-cooperatively or collusively.

This paper provides an empirical evaluation of the temporal efficiency of the U.S. Acid Rain Program, which implemented a nationwide market for trading and banking sulfur dioxide (SO2) emission allowances. We first develop a model of efficient banking and select appropriate parameter values. Then, we use aggregate data from the first seven years of the Acid Rain Program, to assess the temporal efficiency of the observed banking behavior. We find that banking has been surprisingly efficient and we discuss why this finding disagrees with the common perception of excessive banking in this program.