Carbon Emissions Trading: Cap-and-Trade, EU ETS, and Carbon Markets

Published: June 23, 2026

Article by Ryan O'Connell, CFA, FRM

Carbon emissions trading transforms pollution from an unpriced externality into a tradeable commodity. By putting a price on carbon dioxide emissions, these markets create financial incentives for companies to reduce their greenhouse gas output — those who can cut emissions cheaply do so and sell their unused allowances, while those facing high abatement costs buy allowances instead.

Understanding carbon markets is essential for energy traders, utility analysts, ESG investors, and anyone preparing for the CFA exam’s alternative investments curriculum. This guide covers how cap-and-trade systems work, the mechanics of the EU ETS and US carbon markets, allowance allocation methods, carbon price dynamics, and the critical link between carbon prices and electricity markets.

Why Carbon Markets Exist

Without carbon pricing, a coal plant operator pays for fuel, labor, and equipment but nothing for the climate damage caused by emissions. This market failure leads to over-production of carbon-intensive goods because producers do not bear the full social cost.

Carbon markets address this by:

• Capping total emissions — The regulator sets a limit on aggregate emissions that declines over time
• Creating scarcity — Allowances become valuable because supply is limited
• Enabling trade — Firms that can reduce emissions cheaply sell to those facing high costs
• Driving efficiency — The market finds the lowest-cost path to the emissions target

Power generation is the largest single source of industrial CO2 emissions, responsible for roughly 40% of energy-related emissions in developed economies. This makes electricity markets the primary arena where carbon pricing affects investment decisions, dispatch order, and consumer prices.

Cap-and-Trade vs Carbon Tax

Two main policy instruments can put a price on carbon emissions. Each has distinct characteristics that affect price certainty, emissions outcomes, and political feasibility.

Economists often prefer carbon taxes for their simplicity and price stability. However, cap-and-trade has proven more politically viable because it guarantees environmental outcomes and can distribute allowances to ease the transition for affected industries. Hybrid designs — cap-and-trade with price floors and ceilings — combine elements of both approaches.

The EU ETS: The Original Carbon Market

Launched in 2005, the European Union Emissions Trading System was the world’s first major carbon market and remains the largest by trading value. While China’s national ETS now covers more emissions, the EU ETS has deeper liquidity, longer history, and more developed derivative markets.

As of June 2026, EU Allowance (EUA) futures trade around €79-81 per tonne on ICE. The Market Stability Reserve (MSR), introduced in 2019, automatically adjusts allowance supply to prevent the oversupply problems of earlier phases. When the surplus exceeds defined thresholds, allowances are withheld from auctions and placed in the reserve.

US Carbon Markets: RGGI and California

The United States has no federal carbon pricing system, but two major regional markets cover significant portions of the economy.

RGGI has driven significant coal-to-gas switching in the Northeast power sector. Auction revenues — over $11 billion since 2008 — fund energy efficiency programs and renewable energy deployment in participating states.

Allowance Allocation: Free vs Auction

How allowances are initially distributed affects both the economics and politics of carbon markets.

The trend across carbon markets has been toward increased auctioning. The EU ETS moved from nearly 100% free allocation in Phase 1 to majority auctioning in Phase 4. RGGI has auctioned nearly all allowances since inception. Free allocation remains important for sectors exposed to international competition — the EU’s Carbon Border Adjustment Mechanism (CBAM), phasing in from 2026, addresses this by requiring importers to pay for embedded carbon.

Carbon Price Dynamics

Carbon allowance prices respond to fundamental supply and demand factors, policy signals, and interactions with energy markets.

Using typical values for EU power generation:

• Coal plant heat rate: ~10,500 Btu/kWh; emissions factor: ~0.95 tCO₂/MWh
• CCGT heat rate: ~7,000 Btu/kWh; emissions factor: ~0.40 tCO₂/MWh
• At June 2026 fuel prices, the switching price is approximately €50-70/tonne

With EUA prices around €80, gas-fired plants have a clear advantage over coal in the dispatch merit order — explaining the dramatic decline in European coal generation over the past decade.

Key price drivers:

• Cap trajectory — Tighter future caps support higher prices
• Economic activity — Industrial output affects emissions and allowance demand
• Weather — Cold winters and hot summers increase power demand and emissions
• Fuel prices — Gas-coal spread affects switching dynamics
• Policy signals — Regulatory announcements move prices sharply
• Banking behavior — Firms accumulate or release banked allowances based on price expectations

Carbon Offsets and Voluntary Markets

Beyond compliance markets, a parallel ecosystem of carbon offsets and voluntary credits has emerged.

Article 6 of the Paris Agreement establishes rules for international carbon market cooperation, including how countries can trade emissions reductions while avoiding double-counting. This framework is expected to increase linkages between national carbon markets over time.

Carbon and Energy Prices

Carbon prices directly affect electricity generation costs and power market dynamics. Understanding this link is essential for energy traders and infrastructure investors.

For fossil-fuel generators, carbon costs add to the marginal cost of production:

In European markets, traders track “clean spreads” that incorporate carbon costs:

• Clean dark spread = Power price – Coal cost – Carbon cost (for coal plants)
• Clean spark spread = Power price – Gas cost – Carbon cost (for gas plants)

For details on spark spread mechanics, see Spark Spreads in Power Generation.

EU ETS vs RGGI vs California: Carbon Market Comparison

The three major Western carbon markets take different approaches to coverage, pricing, and market design.

The EU ETS price is significantly higher than US markets, reflecting tighter caps and stronger climate policy ambition. However, direct price comparisons require adjustment for scope — RGGI covers only power while California and EU ETS are economy-wide.

Common Mistakes About Carbon Trading

Several widely-held beliefs about carbon markets are either oversimplified or incorrect:

“Carbon trading is just a license to pollute” — The cap is what matters. Companies can trade allowances, but total emissions cannot exceed the cap. Trading ensures reductions happen where they are cheapest, lowering the total cost of meeting climate targets.

“Carbon prices are too volatile to drive investment” — While spot prices fluctuate, forward markets allow hedging years ahead. Companies making long-term capital decisions can lock in carbon costs through futures and forwards. The trend toward price floors also reduces downside uncertainty.

“Free allocation means no carbon cost” — Even freely allocated allowances have an opportunity cost. A firm that uses an allowance to cover emissions foregoes the revenue from selling it. Economic analysis consistently shows that firms pass through carbon costs regardless of how they received allowances.

“Offsets are equivalent to allowances” — Compliance markets strictly limit offset use because offset quality varies. California allows only 4-6% of compliance via offsets from approved protocols. The EU ETS eliminated international offset use after 2020.

“All carbon markets are linked” — Most carbon markets operate independently with different prices and rules. Linkage (like California-Quebec) is the exception. Prices in RGGI, California, and EU ETS can diverge significantly based on local supply and demand.

Limitations of Carbon Markets

Key limitations:

• Political vulnerability — Caps can be loosened; programs can be repealed. Policy uncertainty affects long-term investment signals.
• Incomplete coverage — Most carbon markets cover only a portion of economy-wide emissions. Uncovered sectors may not face carbon price signals.
• Carbon leakage — Without border adjustments, production may shift to jurisdictions without carbon pricing, moving emissions rather than reducing them.
• Distributional effects — Carbon costs can be regressive if passed through to consumer energy prices without offsetting measures.
• Offset quality concerns — Allowing low-quality offsets can undermine environmental integrity. Even weather-related risks affect forestry offsets through fire and drought.
• Price volatility — Sharp price swings can create compliance cost uncertainty, though this has improved with stability mechanisms.

Despite these limitations, carbon markets have proven effective at reducing emissions where implemented. The EU ETS has contributed to a 40% reduction in covered emissions since 2005. RGGI states have cut power sector emissions by over 50% while their economies grew faster than the US average.