Industrial Decarbonisation: GHG Protocol Scopes 1-3 and Corporate PPAs

Industrial decarbonisation does not start with solar panels or with pledges for 2050: it starts with an honest emissions inventory. In the sections below we break down Scopes 1, 2 and 3 of the GHG Protocol with plant-level examples, rank the levers that genuinely cut emissions (efficiency, electrification, self-consumption and the corporate PPA) and draw the line that separates rigorous reporting from greenwashing.

What decarbonising an industrial site means (and what it does not)

Decarbonising an industrial plant means reducing, in a sustained way, the greenhouse gas emissions associated with its activity, measured in tonnes of CO₂ equivalent. The definition sounds obvious, but it is worth pinning down because in practice the term is used for very different things. Buying renewable guarantees of origin for electricity reduces declared Scope 2 emissions, but it does not change a single kilowatt of what the factory consumes. Installing a more efficient boiler does reduce physical emissions. Both actions are legitimate within the accounting rules, but they do not carry the same weight, and a serious strategy distinguishes between them from day one.

Nor is decarbonising a synonym for reaching zero. For most mid-sized manufacturers, the realistic short and medium term objective is a trajectory: knowing how much is emitted today, identifying the main sources, and executing a reduction plan built on investments that stand up economically on their own. What follows is ordered in exactly that sequence: first the measurement framework, then the levers, and finally how to report it without inflating it.

The GHG Protocol: the common language of corporate carbon

The de facto standard for corporate emissions inventories is the GHG Protocol Corporate Standard, developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD). Almost everything else builds on it: the European reporting frameworks, science-based target initiatives such as SBTi, and the questionnaires large companies send to their suppliers all use its taxonomy. That taxonomy divides an organisation's emissions into three scopes, depending on where the combustion or process that generates them physically takes place.

The logic of the split is to avoid double counting between companies: your electricity supplier's Scope 1 is your Scope 2, and your Scope 1 appears as Scope 3 in your customers' inventories. Each tonne is counted once per scope at each link in the chain.

Scope 1: direct emissions, the ones leaving your own stack

Scope 1 groups everything that is burnt or leaks within the organisation's boundary. In a typical process plant, the usual line items are four: stationary combustion (steam boilers, furnaces, dryers burning natural gas, diesel or biomass), mobile combustion (forklifts and own vehicles consuming fuel), process emissions (for example calcination in a cement plant, which releases CO₂ from the chemical reaction itself) and fugitive emissions, above all refrigerant gas leaks in refrigeration installations, whose global warming potentials are hundreds or thousands of times higher than CO₂.

A worked example. A food processing plant consumes 2,000,000 kWh of natural gas per year in its steam boiler. With an emission factor in the region of 0.18 kg CO₂e per kWh of gas (the exact value depends on the official factor applied each year), that boiler generates around 360 tonnes of CO₂e annually. If the refrigeration plant also loses 20 kg of a refrigerant with a warming potential of 2,000, that seemingly minor leak adds another 40 tonnes. The inventory forces you to look at line items that day-to-day operations do not even record.

Scope 2: the electricity you buy, and the two ways to count it

Scope 2 covers the emissions generated to produce the electricity (and district heat or cooling, where applicable) that the company purchases. For many electricity-intensive industries it is the dominant item in the inventory. The GHG Protocol requires it to be reported using two methods in parallel, and the difference between them is where most of the confusion, and most of the marketing, accumulates.

The location-based method applies the average emission factor of the national electricity grid: it reflects the physical reality of the mix arriving at the socket. The market-based method applies the contractual attributes of the purchase: if the company acquires renewable guarantees of origin or signs a PPA with a renewable plant, its market-based Scope 2 can approach zero even though the physical electricity still comes from the same grid. Reporting both numbers, as the standard requires, is the honest way to show the difference between what you consume and what you contract.

Scope 3: the value chain, where most of it usually sits

Scope 3 gathers the fifteen categories of indirect emissions that the GHG Protocol defines along the value chain: from purchased raw materials and contracted transport to employee commuting, waste treatment, and the use and end of life of the products sold. For a manufacturer, it is common for purchased materials (category 1, purchased goods and services) to exceed the sum of Scopes 1 and 2 on their own.

Here, honesty requires acknowledging the limits of the data. Almost nobody measures Scope 3; it is estimated, normally by multiplying purchase amounts or tonnes of material by sector-average emission factors. That estimate is useful for identifying where to concentrate the effort (the purchased steel? the transport? the product in use?), but its precision is limited and only improves when suppliers start providing primary data. The practical recommendation: run a complete screening of the fifteen categories once, rule out the irrelevant ones with a documented justification, and work in detail only on the two or three that are material.

Where to start: measure before you promise

The usual temptation is to start with the solutions: panels, certificates, a target with a round-number year. The right order is the reverse. First, a baseline inventory: a full year of electricity and fuel bills, refrigerant top-up records, fleet consumption and a Scope 3 screening. That builds the map of where the tonnes are. Second, continuous measurement of whatever turns out to be relevant: if electricity is the main item, monitoring by line and by machine turns an annual figure into actionable information, and there a connected energy management platform does the heavy lifting. Third, and only then, targets and an investment plan.

This order is not bureaucracy: it is what stops you buying the wrong lever. A plant whose inventory reveals that 70 per cent of its own emissions come from the boiler's gas does not solve its problem with a green electricity contract, however good it looks in the annual report.

First lever: energy efficiency, the kWh never consumed

The cheapest tonne to eliminate is the one that is never emitted. Cutting consumption by attacking leaking compressed air, oversized motors, unrecovered waste heat or equipment idling under no load trims the bill and Scopes 1 and 2 at the same time, and it usually does so with short paybacks and no dependence on third parties. An energy management system in the style of ISO 50001 (policy, baseline, indicators and continuous improvement) gives that work structure even if the company does not seek certification. We develop the operational detail of this lever in the guide to industrial energy efficiency and ISO 50001 and in our energy efficiency solution.

Second lever: electrifying thermal processes

A growing share of industrial Scope 1 can be converted into Scope 2 by electrifying processes that currently burn fuel. Industrial heat pumps cover an ever wider range of low and medium temperature heat applications (process hot water, drying, cleaning), and electric forklifts have already displaced combustion models in most indoor operations. The move makes sense twice over: electricity can be decarbonised by contract or by on-site generation, while a gas burner will emit the same for its entire service life. The counterpart is that electrification only reduces net emissions if the additional electricity is low-carbon, which links directly to the next two levers.

Third lever: rooftop photovoltaic self-consumption

Photovoltaic self-consumption is the most tangible Scope 2 lever: electricity generated on the plant's own roof, consumed at the foot of the installation, with a real physical reduction in the energy bought from the grid. For industrial profiles with stable daytime consumption, the fraction of demand covered by the solar array stops emitting and stops being billed, and the surplus can be compensated or exported depending on the contracted scheme. Unlike certificates, there is no accounting attribute to argue over here: the self-consumed solar kWh never touches the grid.

Correct sizing (capacity, orientation, storage or not, fit with the load profile) deserves its own guide: we have it at industrial self-consumption: photovoltaic sizing and storage, and turnkey execution is the territory of our industrial solar solution.

Fourth lever: the corporate PPA, explained without the hype

A corporate PPA (Power Purchase Agreement) is a long-term contract, usually running five to fifteen years, under which a company buys the energy of a specific renewable plant at an agreed price. It is the tool large consumers use to stabilise their electricity price and decarbonise their market-based Scope 2 at a scale no rooftop can reach. Its two conceptual variants are worth understanding:

Two honest caveats. The first: a PPA reduces market-based Scope 2, but the real contribution to decarbonising the system depends on additionality, that is, on whether the contract makes viable new renewable capacity that would not otherwise have been built; buying the output of a plant that has been operating for years changes the world less than financing a new one. The second: these are long contracts with price, profile and counterparty risk, historically designed for large consumers, although aggregated formulas exist that open access to mid-sized companies. For a mid-sized manufacturer, the reasonable sequence is usually efficiency and self-consumption first, and a PPA for the residual consumption the roof cannot cover.

Reporting without greenwashing: hygiene rules

The reputational and regulatory risk of overstating climate credentials grows every year, and in Europe the rules on environmental claims are moving towards requiring verifiable substantiation for any green statement. Beyond the legal detail, five hygiene rules keep reporting defensible:

1. Publish both Scope 2 numbers (location-based and market-based), not just the flattering one.
2. Do not declare carbon neutrality resting solely on offsets; always keep in-house reduction separate from offsetting, and treat the latter as a complement, not a substitute.
3. Declare the boundary: which scopes and categories are included, which are excluded and why.
4. Recalculate the baseline when the boundary changes (an acquisition, a closure), instead of claiming the variation as an achievement.
5. Tie every tonne reduced to a specific, verifiable action: the same meter data that supports the bill must support the report.

The good news is that a manufacturer that has done its measurement homework needs no rhetoric: the historical series of kWh and tonnes speaks for itself.

Frequently asked questions on industrial decarbonisation

At CAPTIA Energy we help industrial companies turn decarbonisation into a measurable plan: energy monitoring, efficiency and turnkey photovoltaic self-consumption, with meter data as the basis of any report. Explore our solutions at CAPTIA Energy.