Emissions Trading
What is Emissions Trading?
Emissions trading is a system where a regulator caps total pollution, issues permits equal to that cap, and lets firms buy and sell them.
A regulator decides how much pollution is allowed in total, then issues that many permits, each covering one unit of emissions. Every firm must hold a permit for each unit it releases, so a firm that can cut cheaply has a reason to cut extra and sell its spare permits to a firm that would find cutting expensive. Trading pushes each firm to abate until its marginal abatement cost equals the permit price, which is exactly the condition for meeting the cap at the lowest total cost. Compare this with command-and-control regulation, which orders every firm to cut by the same amount and so forces expensive cuts at some sources while cheap cuts elsewhere go unmade. Emissions trading changes who cuts, not how much gets cut in total.
Emissions Trading: a worked example
Two plants each emit 100 tons, the cap is set at 120 tons, and each plant gets 60 permits, so 80 tons of cuts are needed. Cutting a ton costs Plant A $20 and Plant B $50, so if each simply cuts 40 tons, A spends 40 × $20 = $800 and B spends 40 × $50 = $2,000, for $2,800 in total. Now let B buy A's 40 permits at $35 each: A cuts all 80 tons for 80 × $20 = $1,600 and collects $1,400, a net cost of $200, while B pays $1,400 and cuts nothing. The same 80 tons come out of the air for $1,600 instead of $2,800, and each firm saves $600.
The mistake students make with emissions trading
Students often think trading lets total pollution rise, because a rich firm can buy its way out. The cap fixes total emissions before any trading happens, and a permit one firm buys is a permit another firm gave up, so the total cannot exceed the cap. What trading changes is the location of the cuts, moving them to whoever can make them most cheaply. A second error is treating the permit price as a rate set by officials rather than a price produced by the trades.
Emissions Trading questions
Does emissions trading actually reduce pollution?
Yes, because the cap sets the total quantity of emissions allowed and permits are issued only up to that cap. Trading moves the required cuts to the firms that can make them most cheaply, but it cannot push the total above the cap. Whether the reduction is meaningful depends on how tight the regulator sets the cap.
Is cap and trade the same thing as emissions trading?
Cap and trade is the most common form of emissions trading, in which a fixed number of permits is issued and firms trade them. Emissions trading is the broader label and also covers baseline and credit systems, where a source that beats a required performance level earns credits it can sell. Both rest on the idea that the right to emit can change hands.
Can firms save unused permits for future years?
Many trading programs allow banking, which lets a firm hold an unused permit and surrender it in a later year instead. Banking smooths the permit price over time and rewards firms that cut early, because an early reduction turns into an asset the firm can store or sell. Programs that forbid banking tend to see prices swing sharply at the end of each compliance period.
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