As global concern and crisis awareness regarding climate change continue to rise, pressure for greenhouse gas reduction and the use of renewable energy is increasing from global investors and supply chains. Reporting of non-financial information, such as corporate greenhouse gas emissions and energy usage, is gradually becoming mandatory, making renewable energy use an important issue not only at the national level but also at the corporate level.

Due to structural issues in the power market, domestic companies in South Korea were unable to separately purchase renewable energy. However, with growing demand for corporate renewable energy purchases, the K-RE100 policy for corporate renewable energy purchases was introduced in 2021. The K-RE100 policy provides various compliance methods, including Green Premium, K-RE100 REC purchase, direct Power Purchase Agreements(PPA), and third-party PPA.

The Green Premium allows companies to pay an additional premium on their existing electricity bills to purchase renewable energy from the Korea Electric Power Corporation (KEPCO). However, unlike other procurement methods, renewable energy purchases through the Green Premium do not allow companies to specify the type of renewable energy source, and the reduction achievements are not recognized in emission trading systems. Direct PPA involves a bilateral agreement where companies can purchase electricity and renewable energy certificates(RECs) from renewable energy generators. Additionally, through the K-RE100 REC market, companies can buy electricity from KEPCO and purchase RECs separately from renewable energy generators. With the introduction of the K-RE100 policy, voluntary markets for corporate renewable energy transactions are emerging.

In South Korea, on the other hand, the Renewable Portfolio Standard(RPS) system has been adopted since 2012 to expand the use of renewable energy. The RPS system mandates large power generators to supply a certain percentage of their total electricity production from renewable sources. To fulfill this obligation, large power generators can purchase RECs from renewable energy generators. Consequently, the RPS has led to the formation of a market for renewable energy transactions between large power generators and renewable energy generators.

As a result, the domestic renewable energy transaction market includes the K-RE100, formed by voluntary demand from companies, and the RPS, formed by regulatory measures. Buyers and sellers of renewable energy face the decision of choosing between these two markets. Buyers, such as companies, can purchase renewable energy through various methods in the K-RE100 market, such as Green Premium, K-RE100 REC, and direct PPA. On the other hand, large power generators participate in the RPS market by purchasing RECs. Despite the increasing number of companies in South Korea declaring RE100 participation, actual adoption of PPA and K-RE100 REC purchases has not been activated. According to surveys, companies prefer direct PPA, REC purchases, and Green Premium in that order, but actual compliance is concentrated on the Green Premium. Currently, the renewable energy transaction market does not seem to adequately reflect the demand for corporate renewable energy purchases. In this context, the price of the Green Premium is forming close to the floor set in auctions.

This study constructs a theoretical model for decision-making by renewable energy buyers and sellers in both markets and examines the relationships between compliance methods within the K-RE100 system. Furthermore, the study analyzes the relationships with adjacent systems such as the RPS, emission trading system(ETS), and electricity pricing in the power market.

Analyzing the results of the model, the regulatory characteristics of the RPS have a significant impact on the K-RE100 market. Renewable energy generators receiving high REC weights in the RPS show low incentives to sell in the K-RE100 market. Therefore, companies in the K-RE100 market face difficulties in diversifying renewable energy sources through direct PPA. Additionally, if compensation for renewable energy supply under the RPS increases, transaction volume decreases, and prices rise in the K-RE100 REC market. In situations where the Green Premium or ETS prices are excessively low compared to renewable energy generation costs, PPA and K-RE100 REC markets expreience difficulties, resulting in a bias towards corporate renewable energy purchases through the Green Premium. When electricity prices are lower than wholesale prices, in addition, PPA transactions are challenging to be active.

To adequately reflect the demand for corporate renewable energy purchases in the market, it is necessary to improve the K-RE100 policy by considering the interconnectivity between procurement methods and the additionality of renewable energy. The appropriateness of the Green Premium's price floor and sales volume selection should be reviewed, and continuous improvement and enhancement of direct PPA are required. South Korea's renewable energy policy has progressed based on the RPS, emphasizing obligations and compensation for renewable energy supply. Renewable energy policies should be redesigned by considering both the voluntary demand for corporate renewable energy and the RPS. Simplifying the REC weight distribution is necessary not only to address distortions in supply but also to rectify imbalances between procurement methods within the K-RE100. Furthermore, improvements to the RPS are needed to stimulate demand-side competition in the REC market. Finally, it is essential to recognize that distortions in adjacent systems, such as ETS and the power market, have a significant impact not only on those systems but also on the K-RE100 market.

Preface
Executive Summary

Chapter 1 Introduction

Chapter 2 An Overview and Current Status of the Korean Renewable Energy Trading Market
　Section 1 Status of K-RE100
　Section 2 RPS Status

Chapter 3 Model Analysis
　Section 1 Literature Review
　Section 2 The Model
　Section 3 Balancing Analysis
　Section 4 The Distinction Between Electricity and Certificates

Chapter 4 Conclusions and Policy Implications
　Section 1 Analysis Results
　Section 2 Policy Implications

References
Appendix
ABSTRACT