新能源成本不确定下能源最优开采研究

随着全球气候变暖和环境的恶化,低污染高效率的新能源成为各国能源政策的主要发展对象,因此新能源取代传统能源是大势所趋。针对未来新能源对传统能源的替代趋势,本文通过建立基于社会和企业总效益最大化的能源最优开采的动态模型,分析了新能源成本不确定性和社会风险偏好的差异对能源耗竭速度的影响,并提出了提高社会总收益的合理方案。分析表明：在替代品出现之前能源的开采量随着新能源替代品成本不确定性的增加而增加;而社会风险厌恶倾向于减少社会的最优开采,但是会增加竞争性企业的的开采量;对T时刻之前的能源开采征收额外的税收可以减缓能源耗竭速度,增加社会总收益。最后,本文提出了T时刻之前的能源开采征收额外的税收,或者是对T时刻之后的能源开采进行补贴来实现我国能源最优开采,提高能源利用效率的建议。     

On the theory of the competitive firm with a utility function defined on profits and regret

In this paper we analyze the optimal output determined by a competitive firm facing uncertain demand. We analyze the effect of introducing uncertainty and the effect of increasing uncertainty on the optimal output, under the assumption that the utility function of the firm depends both on profits and on regret. We show that if the firm is more risk averse to profits than to regret (in a sense described below), both effects tend to decrease the optimal output. Similar effects of introducing uncertainty and of increased uncertainty were previously shown by Sandmo (1971) to exist in the case where utility is defined on profits only. Thus, this paper provides conditions under which the above results hold true, even when utility is defined on regret and on profits.     

Renewable Resource Use and Nonseparable Amenity Benefits

We incorporate amenity benefits into an overlapping generations model with a renewable resource as a factor of production, source of amenity benefits and store of value. Unlike the conventional renewable resource problems studied under the assumption of additive consumption and amenity benefits, we let amenity benefits affect the utility of consumers in a nonseparable fashion. We examine the role that weights given to consumption and amenities have for harvesting and the resource stock. We characterize dynamics and stability of steady state equilibria with a logistic resource growth function. We demonstrate in parametric and numerical models that the weights given to consumption and amenities in the utility function matter substantially for the steady state equilibrium stock and its stability and dynamics. Both conventional saddle point equilibria and indeterminacy with infinite number of equilibria and saddle-node bifurcation is possible depending on the weights given to consumption and amenities. In addition, we show that for each inefficient equilibrium stock, there is a unique subsidy rate that can move the economy from an inefficient equilibrium to an efficient one. The presence of indeterminacy provides a challenge to resource policies, because the system becomes unpredictable. Therefore, expectations and market psychology may play an important role in resource utilization and provision of amenities.     

Monitoring as a partially observable decision problem

Monitoring is an important and costly activity in resource management problems such as containing invasive species, protecting endangered species, preventing soil erosion, and regulating contracts for environmental services. Recent studies have viewed optimal monitoring as a Partially Observable Markov Decision Process (POMDP), which provides a framework for sequential decision making under stochastic resource dynamics and uncertainty about the resource state. We present an overview of the POMDP framework and its applications to resource monitoring. We discuss the concept of the information content provided by monitoring systems and illustrate how information content affects optimal monitoring strategies. Finally, we demonstrate how the timing of monitoring in relation to resource treatment and transition can have substantial effects on optimal monitoring strategies.     

A discrete-space urban model with environmental amenities

This paper analyzes the effects of providing environmental amenities associated with open space in a discrete-space urban model and characterizes optimal provision of open space across a metropolitan area. The discrete-space model assumes distinct neighborhoods in which developable land is homogeneous within a neighborhood but heterogeneous across neighborhoods. Open space provides environmental amenities within the neighborhood it is located and may provide amenities in other neighborhoods (amenity spillover). We solve for equilibrium under various assumptions about amenity spillover effects and transportation costs in both open-city (with in- and out-migration) and closed-city (fixed population) versions of the model. Increasing open space tends to increase equilibrium housing density and price within a neighborhood. In an open-city model, open space provision also increases housing density and price in other neighborhoods if there is an amenity spillover effect. In a closed-city model, housing density and prices in other neighborhoods can decrease if the pull of the local amenity value is stronger than the push from reduced availability of developable land. We use numerical simulation to solve for the optimal pattern of open space in two examples: a simple symmetric case and a simulation based on the Twin Cities Metropolitan Area, Minnesota, USA. With no amenity spillover, it is optimal to provide the same amount of open space in all neighborhoods regardless of transportation cost. With amenity spillover effects and relatively high transportation cost, it is optimal to provide open space in a greenbelt at the edge of the city. With low transportation cost, open space is provided throughout the city with the exception of neighborhoods on the periphery of the city, where the majority of the population lives. A greenbelt still occurs but its location is inside the city.     

Does the Optimal Size of a Fish Stock Increase with Environmental Uncertainties?

We analyze the effect of environmental uncertainties on optimal fishery management in a bio-economic fishery model. Unlike most of the literature on resource economics, but in line with ecological models, we allow the different biological processes of survival and recruitment to be affected differently by environmental uncertainties. We show that the overall effect of uncertainty on the optimal size of a fish stock is ambiguous, depending on the prudence of the value function. For the case of a risk-neutral fishery manager, the overall effect depends on the relative magnitude of two opposing effects, the ‘convex-cost effect’ and the ‘gambling effect’. We apply the analysis to the Baltic cod and the North Sea herring fisheries, concluding that for risk neutral agents the net effect of environmental uncertainties on the optimal size of these fish stocks is negative, albeit small in absolute value. Under risk aversion, the effect on optimal stock size is positive for sufficiently high coefficients of constant relative risk aversion.     

Decreasing absolute risk aversion and utility indices derived from cake-eating problems

This paper establishes the following characterization of decreasing absolute risk aversion (DARA) utility indices: J exhibits DARA if and only if it is the indirect function corresponding to an infinite horizon cake-eating problem for some nondecreasing and concave utility function of consumption. The characterization is applied to the analysis of resource extraction under uncertainty and to an inverse optimal problem.     

The effect of environmental uncertainty on the tragedy of the commons

We model a common pool resource game under environmental uncertainty, where individuals in a symmetric group face the dilemma of sharing a common resource. Each player chooses a consumption level and obtains a corresponding share of that resource, but if total consumption exceeds a sustainable level then the resource deteriorates and all players are worse-off. We consider the effect of uncertainty about the sustainable resource size on the outcome of this game. Assuming a general dynamic for resource deterioration, we study the effect of increased ambiguity (i.e., uncertain probabilities pertaining to the common resourceʼs sustainable size). We show that whereas increased risk may lead to more selfish behavior (i.e., to more consumption), increased ambiguity may have the opposite effect.     

Stochastic technical change,non-renewable resource and optimal sustainable growth

We develop a stochastic endogenous growth model involving a non-renewable resource, in which innovation arrivals are governed by a non-stationary Poisson process. Using a CRRA analytical example, we characterize the optimal trajectories of the model and analyze the effects of uncertainty in the sense of Rothschild and Stiglitz by computing a mean-preserving spread. We show that increased variability in the innovation process always implies a smaller optimal R&D effort, since this leads to a reduced marginal rate of return. Effects on the other variables of the model may also be unambiguously identified depending upon the relative risk aversion of agents, the social discount rate and the marginal arrival rate of innovations. Finally, we investigate the conditions under which, on average, the economy reaches a sustainable growth path.     

Time and uncertainty in resource dilemmas: equilibrium solutions and experimental results

Most common pool resource (CPR) dilemmas share two features: they evolve over time and they are managed under environmental uncertainties. We propose a stylized dynamic model that integrates these two dimensions. A distinguishing feature of our model is that the duration of the game is determined endogenously by the users’ collective decisions. In the proposed model, if the resource stock level below which the irreversible event occurs is known in advance, then the optimal resource use coincides with a unique symmetric equilibrium that guarantees survival of the resource. As the uncertainty about the threshold level increases, resource use increases if users adopt decision strategies that quickly deplete the resource stock, but decreases if they adopt path strategies guaranteeing that the unknown threshold level is never exceeded. We show that under relatively high uncertainty about resource size, CPR users frequently implement decision strategies that terminate the game immediately. When this uncertainty is reduced, they maintain a positive resource level for longer durations.     

Export Flexibility And Currency Hedging*

This article studies the behavior of an export‐flexible firm under exchange rate uncertainty. We show that the separation theorem holds if selling exclusively in the domestic market is suboptimal even under the most unfavorable spot exchange rate. Otherwise, the firm's optimal output depends on its preferences and on the underlying uncertainty. We further show that the full‐hedging theorem holds only when the firm always finds it optimal to sell its entire output in the foreign market. Otherwise, export flexibility introduces a convexity into the firm's foreign exchange risk exposure, which calls for the use of currency options for hedging purposes.     

Long-run industry equilibrium with uncertainty

In this paper we consider the effects of uncertainty on industry equilibrium when firms must commit themselves to production before prices are revealed. We show that (a) an increase in demand uncertainty will (i) not affect the equilibrium number and size of firms if they are risk neutral, (ii) reduce the equilibrium number of firms if they are risk averse, but will have an ambiguous effect on their size. (b) In equilibrium, firms operate at capacity if they are risk neutral, but at excess capacity if they are risk averse.     

Increasing risk and equilibrium under uncertainty

The impact of increasing risk on social welfare and resource allocation is analysed in a general equilibrium model with endowment uncertainty. It is shown that the equilibrium allocation of resources is affected only by an increase in those risks which are important for society as a whole. In contrast, increases in purely individual risk do not influence achievable social welfare and have no effect on the utility of traders in a competitive market.     

On Environmental Taxation under Uncertain Environmental Damage

This paper addresses optimal taxation, when therelationship between the consumption of a`dirty' good and the resulting environmentaldamage is uncertain and treated as a randomvariable by policy makers. The main purpose isto analyze how increased uncertainty, measuredas a mean preserving increase in the spread ofthis random variable, affects the optimalcommodity tax on the dirty consumption good. Incase the only task of government is to correctthe environmental externality, and if thepreferences are characterized by nondecreasingabsolute risk aversion, we find that thecommodity tax on the dirty consumption goodincreases in response to additionaluncertainty. If, on the other hand, thegovernment provides a public good and uses alump-sum tax in addition to the commodity tax,it is possible that the commodity tax decreasesas a response to additional uncertainty, evenif the preferences are characterized bynondecreasing absolute risk aversion. A similarresult emerges, although for different reasons,if the lump-sum tax is replaced by a laborincome tax.     

Currency Options and Export-Flexible Firms

This paper examines the production and hedging decisions of a globally competitive firm under exchange rate uncertainty. The firm is risk averse and possesses export flexibility in that it can distribute its output to either the domestic market or a foreign market after observing the realized spot exchange rate. To hedge against its exchange rate risk exposure, the firm can trade fairly priced currency call options of an arbitrary strike price. We show that both the separation and the full‐hedging results hold if the strike price of the currency call options is set equal to the ratio of the domestic and foreign selling prices. Otherwise, neither result holds. Specifically, we show that the optimal level of output is always less than that of an otherwise identical firm that is risk neutral. Furthermore, an under‐hedge (over‐hedge) is optimal whenever the strike price of the currency call options is below (above) the ratio of the domestic and foreign selling prices.     

Export-Flexible Firms and Forward Markets

This paper examines the production and hedging decisions of an exporting firm under exchange rate uncertainty. The firm is export flexible in that it can distribute its output to either the domestic market or a foreign market, after observing the realized spot exchange rate. The firm is a monopoly in the domestic market but a price-taker in the foreign market. It is shown that the separation theorem holds if selling exclusively in the domestic market is suboptimal even under the most unfavorable sport exchange rate. Otherwise, the firm's optimal output depends on its preference and on the underlying exchange rate uncertainty. Furthermore, the export-flexible firm underhedges its exchange rate risk exposure in a currency forward market wherein the forward exchange rate contains a non-positive risk premium. [D21, F31]     

Climate Policy Under Uncertain and Heterogeneous Climate Damages

We highlight that uncertainty about climate damages and the fact that damages will be distributed heterogeneously across the global population can jointly be an argument for substantially stricter climate policy even if uncertainty and heterogeneity in isolation are not. The reason is that a given climate risk borne by fewer people implies greater welfare losses. However, these losses turn out to be significant only if society is both risk and inequality averse and if climate damages are highly heterogeneous. We discuss how insurance and self-insurance of climate risk could theoretically mitigate this joint effect of uncertainty and heterogeneity and thus admit weaker climate policy. Insurance provides more efficient risk sharing and self-insurance allows strongly impacted individuals to compensate damages by increasing savings. We first use a simple analytical model to introduce the different concepts and then provide more realistic results from the integrated assessment model DICE.     

Optimal sequential contract with a risk‐averse supplier

We study optimal contracts in environments where a risk‐averse supplier discovers cost information privately and gradually over time: the supplier is privately informed about its cost uncertainty at the time of contracting and discovers the realization of cost condition privately after contracting and before production. We show that both the buyer and the supplier prefer more cost uncertainty when the supplier is not very risk‐averse but less cost uncertainty when the supplier is sufficiently risk‐averse. However, the buyer always prefers to contract before the cost uncertainty resolves regardless of the supplier's degree of risk aversion. The nature of the optimal contract also depends on the supplier's risk preference. A separating contract is optimal when the supplier is not very risk‐averse; however, a pooling contract, which offers the same contract terms regardless of the cost uncertainty, can be optimal when the supplier becomes sufficiently risk‐averse. Moreover, the optimal production schedule is often characterized by “inflexible rules.”     

Uncertainty and sustainability in the management of rangelands

We analyze a dynamic and stochastic ecological-economic model of grazing management in semi-arid rangelands. The ecosystem is driven by stochastic precipitation. A risk averse farmer chooses a grazing management strategy under uncertainty such as to maximize expected utility from farming income. Grazing management strategies are rules about which share of the rangeland is given rest depending on the actual rainfall in that year. In a first step we determine a myopic farmer's optimal grazing management strategy and show that a risk averse farmer chooses a strategy such as to obtain insurance from the ecosystem: the optimal strategy reduces income variability, but yields less mean income than possible. In a second step we analyze the long-run ecological and economic impact of different strategies. We conclude that a myopic farmer, if he is sufficiently risk averse, will choose a sustainable grazing management strategy, even if he does not take into account long-term ecological and economic benefits of conservative strategies.     

The trade-off between risk and incentives in fiscal federalism: Evidence from China

A central argument of the second-generation fiscal federalism literature is that allocating a considerable share of tax revenue to local governments can provide fiscal incentives for local officials to promote economic growth. However, increasing incentives will increase the costs of uncertainty if local government officials are risk averse. Building on the insights of the classic principal-agent models, we predict that the optimal share of tax revenues retained by local government will decrease as the uncertainty of total tax revenues increases. Using Chinese provincial data, we find a robust negative relationship between volatility and the tax-sharing ratio at the sub-provincial level. Our results indicate that optimal decentralization in developing countries balances the trade-off between risk and incentives.