November 28, 2024.

Drawing a parallel with those considered undesirable, coal today is regarded as an “unwelcome” fuel due to the high pollution load generated by its combustion. This is why there is a state policy, with a defined roadmap, to eliminate its participation in the national electricity matrix before 2040.

In fact, the decarbonization plan (whose ongoing update includes 45 measures) has already made progress. For example, April 16 of this year was the last operational day for AES Andes’ Norgener coal-fired power plant, located in Tocopilla. Its two units, totaling 276 MW, were disconnected from the National Electric System almost two years ahead of the originally committed date (December 31, 2025). Its early closure will prevent the consumption of nearly 1.2 million tons of coal and the emission of up to 5 million tons of carbon dioxide (CO2). Just a few weeks later, Engie requested the National Energy Commission to cease operations at the Andina and Hornitos thermoelectric plants, located in the Mejillones Thermal Complex, by December 31, 2025, effectively eliminating coal from their electricity generation.

Also, in an effort to further reduce emissions from thermal plants, the Ministry of the Environment (MMA) has developed a draft revision of Supreme Decree No. 13 (DS 13 – 2011) to establish stricter limits for particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx).

Significant Reduction

According to Rodrigo Barraza, academic and researcher at the Energy Transition Center of the Faculty of Engineering and Sciences at Universidad Adolfo Ibáñez (Centra-UAI) and the Solar Energy Research Center (SERC Chile), the application of DS 13 − which introduced continuous monitoring requirements and differentiated between existing and new units − forced older, more polluting plants to install emission control technologies to comply with the regulation. “Emission control systems like bag filters or electrostatic precipitators for PM, gas scrubbers for SO2, and SCR and NSCR reduction systems for NOx enabled efficiencies of over 99% for PM, 95% for SO2, and 50% for NOx. This resulted in a significant reduction in emissions, improving air quality by around 20% in areas like Quintero, according to local monitoring station data,” he states.

With a similarly positive assessment, Jorge Araya, Projects and Sales Manager at Better − a company specializing in environmental consulting and advice − points out that DS 13, which also regulates mercury (Hg) discharges, “has been crucial in setting emission limits for thermoelectric plants, regardless of the type of fuel used, improving air quality in the geographical areas where they are located. It was one of the first important steps in the decarbonization process being driven in Chile, followed by other public policies, such as the coal plant closure plan announced in 2021.”

Along with highlighting the different technologies used to control emissions, he adds that “with the digitalization of processes, plant efficiency has been optimized, minimizing fuel consumption. Online monitoring, which is publicly available, allows for the detection of emission level non-compliance, enabling self-regulation by generators to stay within the limits set by DS 13.”

Colbún’s Reality

The generator Colbún currently operates two natural gas plants, one diesel-based plant, and a fourth plant that uses coal, all of which are equipped with continuous emission monitoring systems that provide real-time data to the Superintendency of the Environment. “These systems show that Colbún’s thermal plants have fully complied with the emission limits set by DS 13,” reveals Daniel Gordon, Sustainability and Corporate Affairs Manager at the company. He adds that the plants use different emission reduction and control technologies. At the Santa María coal plant, there is an electrostatic precipitator for particulate matter, a desulfurizer for SO2 emissions, and Low-Nox burners for nitrogen oxide emissions. The gas plants have no particulate matter emissions, and NOx is controlled through water injection or so-called “DLN” systems.

Regarding the future of Santa María, the executive indicates that the possibility of advancing its closure before 2040 “will depend on the development of enabling conditions, including strengthening transmission lines, large-scale storage deployment (batteries), and the existence of incentives for demand to also play a role in increasing system flexibility. It is important to note that Santa María is the only available base-load thermal plant in central-southern Chile, highlighting the fragility of the system in dry years with low wind production—scenarios that are entirely feasible—where this plant plays a key role in keeping the central-southern system operating reliably and cost-efficiently.”

New Limits

Since February 2020, DS 13 has been under review by the MMA. According to Barraza, the proposed update “introduces stricter limits for pollutants like mercury, nickel, and vanadium, which were not previously regulated. Additionally, it is proposed that plants installed before 2011 must comply with the standards applicable to newer plants.

These measures could lead to further improvements in air quality, although they would require significant investments from thermal power generators to implement more advanced control technologies.” Araya adds, “All signs point to increased requirements for already-regulated pollutants, along with the inclusion of some new ones. For generators, this will entail investments in control technologies and possibly the conversion of equipment or even the closure of facilities that cannot meet the new standards. This scenario could also encourage greater adoption of renewable energy.” Regarding the impact of the new regulations on Colbún’s thermal plants, Gordon specifies that “it will ultimately depend on the limits set and other compliance variables established by the updated regulation. What is important is that the limits are set based on technical criteria that take into account the progress made by Chile’s decarbonization plan and the significant advances in emission reductions in the electricity sector.”

Courtesy of Revista Electricidad