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Emissions and Energy - Nexa | 2017 Annual Report

Material Issue
Emissions and Energy

Note 19: The data published from 2014 to 2016 were recalculated because of the inclusion of the emissions generated in the ores transportation between Peru and Brazil. GRI 103-1, 103-2, 103-3

Weather is a highly relevant aspect for our business, mainly due to its influence on the hydrological scenario. Intense climate change can adversely affect our operations, causing numerous problems, including postponing schedules and, consequently, increasing operating costs. These are risk factors to the business and hamper the achievement of goals and the development of projects, as happened in early 2017 in operations in Peru, affected by heavy rains.

To consolidate our commitment to the theme and to collaborate in the strengthening of a low carbon economy and an increasingly sustainable society, we have set ourselves the target of reducing greenhouse gas (GHG) emissions by 5% per tonne of product by 2025.

Toward this aim, we have adopted a set of initiatives for adaptation and mitigation of impacts, inventory of greenhouse gas emissions (GHG) and constant guidance and monitoring. In addition, our investments in this field in recent years have focused on energy efficiency and flexibility of the energy matrix, with a focus on renewable sources and technological innovation projects.


In 2017, we put a biomass boiler into operation in the Três Marias unit, replacing the boilers burning fossil fuels derived from oil; this action avoided the consumption of 15,612 tonnes of this fuel over the year. The new structure, which aims to reduce the unit’s fuel costs and carbon emissions, uses eucalyptus chips and/or sugarcane bagasse produced in the region as fuel. The next step is to introduce the biomass operate into the unit for steam production.

With the boiler changeover, we reduced CO2 emissions by 33,362 tons in the unit (from February to December) — which accounts for approximately 22.1% of all the plant’s emissions. The expected savings from energy cost reductions was US$ 3.7 million. In addition, social gains were achieved by fostering the productive chain and contributing to the promotion of agricultural development in the region.

Another important initiative occurred at the Cajamarquilla unit in Peru, replacing liquid fuels (diesel oil) with natural gas; this was made possible by the installation of a gas pipeline in the region. The project, currently in the process of obtaining a license, will begin to be set up in 2018 for a 2019 start-up date, reducing the plant’s emissions and fuel expenditures.

Also noteworthy are the investments in innovation through the Mining Lab program. Of the five initiatives selected in 2016 and already under study for implementation, three are aimed at energy efficiency and emission reduction projects. One of them includes the construction of a steam plant at the Três Marias unit (more information in the Innovation and Technology chapter).

In power generation, we have two studies being conducted: the first is the installation of a solar power unit at the Fortaleza de Minas unit, with a capacity to generate 30MW; and the second includes a small hydroelectric plant at Vazante, with capacity of 1.4MW.

Energy Consumption

Energy consumption in our operations for the year was 14,846,904 GJ, a reduction of 2.5% compared to 2016 (15,220,284 GJ), with 84.1% from renewable sources (80.7% in 2016). This proportion is reflected especially the electric power matrixes of Brazil and Peru, since both of their bases are made up of a greater share of water sources. GRI 302-1

In the year, electricity generation accounted for 18.9% of total consumption. There is cogeneration in steam boilers and generation at power plants and small hydropower projects managed by Votorantim Energia (which serves the subsidiaries of Votorantim S.A. as well as external clients).

Consumption of Energy Inside and Outside the Organization in GJ GRI 302-1, GRI 302-2

Characteristics of the Energy Matrix
(GJ) GRI 302-1

Atmospheric Emissions

In 2017, greenhouse gases (GHGs) from our operations totaled 927,979 tCO2e, representing a 5% reduction over the previous year (975,511 tCO2e). Emissions from electricity consumption (Scope 2) accounted for 71% of the total. The emission intensity was reducted to 0.879 tCO2e per tonne of zinc produced.

Greenhouse Gas Emissions (tco2e) GRI 305-1, 305-2, 305-3

Greenhouse Gas Emissions by Scope –
GRI 305-1, 305-2, 305-3

Energy intensity
GJ/tonne of product GRI 302-3

Intensity of GHG Emissions
(tonCO2e/tonne of product) GRI 305-4