Carbon pricing, whether through trading or taxes, is considered one of the most important policies to reduce emissions. A price on carbon increases the operating costs of high carbon fuels relative to lower-carbon alternatives. This post introduces an index (termed Coal to Clean Carbon Price Index – C3PI) for approximating the carbon price required to leapfrog fossil gas and support an electricity system predominantly supplied by variable renewable energy.
Fuel switch costs in electricity have historically been analysed through coal and fossil gas generation prices. Fossil gas has a lower carbon intensity than coal, so if the carbon price gets high enough it becomes more economic to burn gas than coal. This level is termed the fuel switch price.
We have taken fuel switch analysis a step further, by calculating the fuel switch cost required to leapfrog fossil gas and transition directly to dispatchable renewables. The coal-to-clean fuel switch price captures the difference in cost associated with operating existing coal and new onshore wind or solar photovoltaics (PV) plus battery storage.
The good news is, due to the declining cost of renewable energy and battery storage coupled with the increasing price volatility of gas, we found it is now cheaper to switch from coal-to-clean than coal-to-gas. Based on a global average derived from C3PI, the carbon price required to switch from existing coal to existing gas has so far averaged $235/tCO2 in 2022, while the carbon price to switch from existing coal to new solar PV or onshore wind plus battery storage was just –$62/tCO2. This represents an extraordinary decline of 99% since 2010.
There is considerable regional variation in the carbon price needed to replace existing coal with renewable energy and battery storage. These variations are due to factors on both the supply side and demand side. The price is negative in Europe due to rising carbon prices from policy reforms to the ETS, decades of policy support for renewable energy – and Russia’s invasion of Ukraine, which has resulted in a marked rise in the price of thermal coal. Due to discriminatory regulations and land-use constraints, Japan has one of the highest coal-to-clean fuel switch prices. China and the US are world leaders in renewable energy, but lower domestic coal prices partially offset these cost advantages. Fuel switch costs in Southeast Asia are influenced by the subsidisation of coal and gas, as well as the renewable energy being a nascent industry compared to other countries. Despite this, all regions show a clear deflationary trend in the cost of switching from coal-to-clean. These findings call into question the 615GW of gas and 442GW of coal under construction and proposed globally.