Internalisation of externalities

Also called: Externality pricing · Topic: Environment and Sustainable Development · NCERT: Beyond NCERT

Meaning

Internalisation of externalities means making the person who causes an external cost (or benefit) carry it in their own accounts. Once that happens, their private cost becomes equal to the full cost to society.

• Formula: Marginal Social Cost (MSC) = Marginal Private Cost (MPC) + Marginal External Cost (MEC)
• Why it matters: When a polluter does not pay for the harm it causes, its product looks cheaper than it really is. So society makes and uses too much of it. Internalisation fixes this by putting a price on the harm. Carbon taxes, cap-and-trade and India's carbon market are all built on this idea.

Explanation

Why an externality needs to be internalised

• Externality: a cost or benefit that falls on people outside a deal. The buyer and the seller do not pay for it.
• Pollution is a negative externality. Take a coal power plant:
• Its price covers fuel, labour and capital.
• Its smoke harms nearby farms and people's lungs, and it adds to global warming. Nobody bills the plant for this damage.

• So the power looks cheap, and society makes and uses too much of it.

• Three cost terms:

• MPC (marginal private cost): what it costs the firm to make one more unit.
• MEC (marginal external cost, or marginal damage): the harm that one extra unit does to other people.

• MSC = MPC + MEC. Internalisation makes the firm face the MSC, not just the MPC.

• The reverse case: when an activity helps others (a positive externality), a subsidy can reward the person doing it. This is the "beneficiary" side of the idea.

Three routes to internalisation

Route	How it works	Weakness
Pigouvian tax	A tax on each unit of pollution, set equal to the marginal damage	The regulator must know how big the damage is
Tradable permits (cap-and-trade)	The government fixes total pollution, issues that many permits, and firms trade them	Needs good monitoring and a registry (a record of who holds which permits)
Coasean bargaining	The polluter and the victims settle it by private negotiation	Works only when property rights are clear and few parties are involved. It fails for climate change, where billions of people are affected.

• Worked example: Pigouvian tax
• One tonne of CO₂ causes ₹2,000 of damage, so the government sets a tax of ₹2,000/t.
• The firm keeps cutting emissions as long as cutting one tonne costs less than ₹2,000, because cutting is cheaper than paying the tax.
• It stops when its marginal abatement cost (the cost of cutting one more tonne) reaches ₹2,000.
• At that point, the cost of cutting the last tonne equals the damage that tonne would cause. This is the efficient level of pollution.

Price route vs quantity route

	Carbon tax	Cap-and-trade (ETS)
What the government fixes	The price per tonne	The quantity (the cap on total emissions)
What stays uncertain	How much emissions fall	The permit price
Main strength	Steady revenue that can be recycled (for example, cash transfers to the poor)	The market finds the cheapest cuts, and total emissions are certain
Example	Sweden	EU ETS (2005); China national ETS (2021)

• Worked example: why trading lowers cost
• Firm A can cut CO₂ at ₹500/t. Firm B can cut CO₂ at ₹3,000/t. Together they must cut 100 t.
• Without trading, each cuts 50 t: (50 × 500) + (50 × 3,000) = ₹1,75,000.
• With trading, A cuts all 100 t for ₹50,000 and sells 50 permits to B. The permit price settles between ₹500 and ₹3,000.

• Society meets the same cap and saves ₹1,25,000.

• Global spread: there are 80 carbon pricing instruments (43 carbon taxes and 37 ETSs). Together they cover about 28% of global GHG emissions (2025) [5].

• Revenue: carbon pricing revenue was more than US$100 billion in 2024 [4].

What sets the "right" price

• Social cost of carbon (SCC): the present value of all future damage from emitting one more tonne of CO₂. It is the benchmark for a Pigouvian carbon price.
• The US EPA estimated about $190/t in 2023. That estimate was later withdrawn.
• Formula: PV = D / (1 + r)^t, where D = future damage, r = discount rate and t = years from now.
• Example: ₹10,000 of damage 50 years from now is worth ≈ ₹3,715 today at r = 2%, but only ≈ ₹872 at r = 5%.

• Lesson: the discount rate (how much less we value the future) changes the price more than any other assumption. Choosing it is an ethical question about how much weight we give future generations.

• Opposite force: fossil fuel subsidies. These act as a negative carbon price: the state pays people to pollute instead of charging them.

• The IMF estimates global fossil fuel subsidies at US$7 trillion in 2022, or 7.1% of world GDP. Of this, 82% was implicit, meaning environmental damage that nobody was charged for [6].

In India

• No explicit, economy-wide carbon tax. India puts a price on carbon implicitly (indirectly, through other taxes):
• Clean Energy Cess on coal (a cess is a tax collected for a specific purpose): ₹50/t in 2010, raised to ₹400/t by 2016, and subsumed into the GST compensation cess in 2017. How coal is taxed after the 2025 GST changes still needs to be checked.
• Excise duty on petrol and diesel, which works like a carbon tax on transport.
• Green tax on old vehicles, which pushes owners to retire polluting vehicles.

• Delhi's Environment Compensation Charge (ECC) on trucks entering the city.

• Removing negative carbon prices:

• Petrol prices were decontrolled in 2010 and diesel prices in 2014.

• The LPG subsidy was moved to DBT (Direct Benefit Transfer: money goes straight into the bank account, so less leaks to people it was not meant for).

• Carbon Credit Trading Scheme (CCTS), 2023:

• The legal power for it comes from the Energy Conservation (Amendment) Act, 2022.
• Notified in June 2023, it created the Indian Carbon Market (ICM). Its aim is to price GHG emissions through tradable Carbon Credit Certificates (CCCs) [2].
• Institutions: BEE (Bureau of Energy Efficiency) is the administrator, Grid-India is the registry, and CERC (Central Electricity Regulatory Commission) regulates trading.
• Targets are emissions intensity, not absolute caps. Obligated entities get GHG Emission Intensity (GEI) targets, measured as tonnes of CO₂e per tonne of product [2][3].
• The first targets covered 7 sectors that came over from PAT: aluminium, cement, chlor-alkali, petrochemicals, petroleum refineries, pulp and paper, and textiles [2]. GEI targets were later notified for 208 more carbon-intensive units [1].

• Example: a cement plant has a target of 0.60 t CO₂e per tonne of cement and makes 10 lakh t, so it may emit 6 lakh t. It actually emits at 0.57 t per tonne, which is 5.7 lakh t. So it earns 30,000 CCCs to sell.

• Earlier steps: the PAT scheme (2012), where plants trade ESCerts (Energy Saving Certificates), and RECs (Renewable Energy Certificates).

Don't confuse with

• Internal carbon price: a make-believe price per tonne that a company uses when it compares its own projects. It is a planning tool, not a tax, and nobody actually pays it.
• Explicit vs implicit subsidy (IMF): an explicit subsidy means selling fuel below its supply cost. An implicit subsidy means not charging for environmental damage. An implicit subsidy is simply an externality that has not been internalised.
• Green Credit vs carbon credit: a carbon credit is a certified tonne of CO₂e reduced, avoided or removed. A Green Credit rewards actions such as tree planting or water conservation. It is not a tonne of CO₂e.
• Carbon leakage: this is not internalisation. It is a side effect of internalising in only some countries: production moves to countries with weaker climate rules. The EU's CBAM tries to stop it by charging for the carbon embodied in imports (definitive phase from 2026).

Prelims Hooks

• MSC = MPC + MEC. Internalisation makes the polluter face the MSC.
• Pigouvian tax = a tax on each unit of pollution equal to the marginal external damage. Coasean bargaining needs clear property rights and few parties.
• Carbon tax fixes the price. Cap-and-trade fixes the quantity. EU ETS started in 2005; China's national ETS in 2021.
• CCTS 2023 was notified under the Energy Conservation (Amendment) Act 2022. BEE = administrator, Grid-India = registry, CERC = trading regulator. Its targets are intensity-based (GEI), not absolute caps [2].
• Trap: India has no explicit carbon tax. The Clean Energy Cess on coal (₹50/t in 2010 → ₹400/t in 2016) was subsumed into the GST compensation cess in 2017.
• IMF: fossil fuel subsidies were US$7 trillion (7.1% of world GDP) in 2022, and 82% of that was implicit [6].

Mains Points

• Tax vs trade for India:
• A carbon tax gives certain revenue and is simple to run, which suits a country with limited capacity to monitor emissions.
• An intensity-based ETS (CCTS) lets output grow while still rewarding efficient plants. This fits India's NDC, which is framed as an emissions-intensity-of-GDP target.

• The trade-off: intensity targets do not guarantee that absolute emissions will fall.

• Remove negative carbon prices first:

• Implicit subsidies (82% of the global total) work against internalisation [6].
• India's fuel decontrol and DBT for LPG show that subsidies can be reformed when targeted cash support protects the poor.

• The revenue can fund a just transition for coal-dependent states.

• CBAM and CBDR (GS-II/III):

• The EU's CBAM internalises carbon at the border, but India calls it unilateral and against CBDR (Common But Differentiated Responsibilities: rich countries, which caused most past emissions, should carry a bigger burden).
• A credible domestic carbon price (CCTS) can help Indian exporters claim a deduction, because carbon already paid for at home can reduce the CBAM charge.
• Strong MRV (Monitoring, Reporting and Verification) is needed so that credits reflect real cuts.

Related concepts

• Carbon pricing
• Green tax
• Social cost of carbon
• Internal carbon price
• Fossil fuel subsidies
• Cap-and-trade
• Carbon market
• Compliance carbon market
• Voluntary carbon market
• Carbon credit

Read more

• Pricing pollution: carbon taxes, cap-and-trade and carbon markets