RE100 for Korean Semiconductor Suppliers: Where to Start

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There is one question we have had more than any other from heads of small and mid-sized manufacturers over the past month.

"Our customer is asking for RE100 data. What on earth do we do first?"

Most supplier staff see RE100 as an enormously complicated, huge project, but in fact the start is unexpectedly simple.

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Why start now?

If you do not start answering RE100 now, you could be pushed out by your customers somewhere between 2027 and 2028. That is not an exaggeration. From a supplier's point of view, the following three pressures are arriving at the same time.

Impact · The three pressures arriving on suppliers at the same time

Pressure from global OEMs

Risk

Clients asking directly for RE100 and carbon data

• Apple — 100% RE100 mandated for tier 1 and tier 2 suppliers by 2030
• BMW and Tesla — product-level carbon emissions data required from 2026
• Without Scope 1 and 2 data, doing business at all becomes difficult

EU CBAM in full effect

Risk

Costs passed down to suppliers even without direct exports

• From 2026, carbon costs fall on manufacturers exporting to the EU directly and indirectly alike
• A strong possibility that large companies pass the cost on to suppliers
• For example: supplier → Hyundai Motor, POSCO, Samsung → export to the EU, the whole flow affected

KEPCO industrial tariff reform

Risk

Higher evening prices make acting on your own urgent

• The time-of-use tariff for Industrial (B) was reformed on 16 April 2026
• Prices raised for the evening, 18:00~21:00
• A point at which reviewing self-generation and PPAs becomes more urgent

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So what do you do first? — a five-step roadmap

STEP 1. Establish where you stand — 1 week

The core: work out exactly how much electricity your company uses in a year and how much carbon it emits.

You need two things.

• Download 12 months of electricity bills from KEPCO's Cyber Branch
• Pull together a year of city gas and fuel use records

From this data you work out your company's annual electricity consumption (kWh) and annual carbon emissions (tCO₂eq). If you get stuck on the Scope 2 calculation, see the practical guide to calculating Scope 2 emissions.

STEP 2. Confirm what your customers require — 1~2 weeks

The core: find out what RE100 recognition criteria your key customers hold.

This is the most important step, and surprisingly many companies skip it. RE100 recognition criteria differ from customer to customer, and if you buy up a lot of a route your customer does not recognise, that cost is simply sunk.

Ask your customer's ESG staff directly, or check the customer's ESG report. The SK and Samsung supplier assessment checklist sets out the list of routes both companies recognise.

STEP 3. Assess your CBAM exposure — 1 week

The core: check whether you export to the EU, or supply a large company that does.

A company that does not export to the EU directly can still fall within indirect CBAM range. For example, if your company sits in any of the flows below, answering CBAM is unavoidable.

• Automotive parts → Hyundai Motor → export to the EU
• Processed steel → POSCO → export to the EU
• Aluminium parts → Samsung Electronics → export to the EU

Start with a self-assessment using the CBAM quarterly report template.

STEP 4. Compare the RE100 compliance routes — 2 weeks

The core: decide which mix of the five compliance routes fits your company.

There are five RE100 compliance routes recognised by the Korean government.

1. Green premium — pay KEPCO an additional charge and have it recognised
2. REC purchase — buy certificates directly
3. Third-party PPA / direct PPA — a long-term contract with a generation business
4. Equity investment — investing in a renewable generation business
5. Self-generation (self-consumption) — installing your own equipment

The cost, the timescale and the degree of international recognition are completely different for each. The standard portfolio for a Korean mid-sized manufacturer usually looks like this.

Portfolio · The standard RE100 portfolio for a Korean mid-sized manufacturer (a mix of 4 routes, at median values)

100%

Standard mix

• Third-party / direct PPA40%

  Long-term stability, the highest international recognition

• Self-generation25%

  A stable base, with a lower electricity bill alongside

• REC purchase25%

  Flexible top-up, timing under your control

• Green premium10%

  Low-cost filler, limited international recognition

These proportions vary a great deal with a company's circumstances.

• A cramped factory site → less self-generation, more PPA and REC
• Limited funds → REC and green premium first
• Dealing with top-tier global buyers → self-generation plus a PPA strongly recommended

A one-page comparison of the price, contract term and scope of recognition for each route is set out in the REC, green premium and PPA comparison table.

STEP 5. Read your KEPCO bill closely — alongside the rest

The core: find the clues for your RE100 strategy in the electricity bill you receive every month.

Most plant staff look only at the amount billed and send the KEPCO bill up for approval. But that single sheet contains all the core information for an RE100 strategy.

• Annual electricity consumption → the basis for deciding the RE100 volume you need
• Usage pattern by time of day → judging how well self-generation fits
• Maximum demand → deciding the right capacity for self-generation
• Contract power → the scope for an immediate saving
• Power factor → a further point to save on

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How long do the five steps take?

Where a member of staff runs this alongside their normal job, the flow through the steps is as follows.

Roadmap · The five steps where staff run them alongside their normal job

STEP 1

Establish where you stand

1 week

Electricity bills + a spreadsheet

STEP 2

Confirm what customers require

1~2 weeks

Interview the ESG staff

STEP 3

Assess CBAM exposure

1 week

A self-assessment checklist

STEP 4

Compare the compliance routes

2 weeks

50% in-house, 50% advisory

STEP 5

Read the bill closely

alongside the rest

A specialist is recommended

1. 1

   STEP 1

   1 week

   Establish where you stand

   Electricity bills + a spreadsheet

2. 2

   STEP 2

   1~2 weeks

   Confirm what customers require

   Interview the ESG staff

3. 3

   STEP 3

   1 week

   Assess CBAM exposure

   A self-assessment checklist

4. 4

   STEP 4

   2 weeks

   Compare the compliance routes

   50% in-house, 50% advisory

5. 5

   STEP 5

   alongside the rest

   Read the bill closely

   A specialist is recommended

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Three questions we are often asked

Q. We are a small company. Do we really have to do RE100 too?

The size of the company does not matter. What counts is whether your customer's customer is an RE100 member.

Even a parts maker with 30 employees will be asked for RE100 data if the tier 1 supplier receiving those parts is a Samsung or SK supplier. It is not the size of your company but the flow of the supply chain that decides.

Q. Isn't it going to cost far too much?

Starting costs KRW 0.

• STEP 1 to 3 can be done with free material alone
• STEP 4 and 5 involve external advisory fees of roughly KRW 1~3 million (for a mid-sized company)
• Actual RE100 compliance (REC, PPA, self-generation) is done in stages

You have to think of the "cost of starting" and the "cost of executing" separately. Start light, execute in stages.

Q. Our customers have not asked yet. Is there any need to do this in advance?

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• [Source: Korea Energy Agency, the K-RE100 scheme]
• [Source: Apple Supplier Clean Energy Program]
• [Source: Official EU CBAM information (European Commission)]
• [Source: KEPCO industrial electricity tariff]

Note: Schemes, prices and policies may change. Please check the latest guidance from the official bodies before you commit.

Related · Worth reading next

Procurement options

K-RE100 five routes

Cost, term and risk compared

K-RE100's Five Compliance Routes Compared: Which Mix Fits Your Plant

06/27/26