Greenhouse gases

The need to report greenhouse gas emissions is becoming increasingly evident globally and South Africa is no exception. In the past, AECI has provided data related to certain aspects of this, including electricity consumption and carbon dioxide (CO₂) emissions.

AECI took part in the Carbon Disclosure Project in 2009, which is being promoted in South Africa by the National Business Initiative.

During the reporting year, a decision was taken to develop a carbon footprint for the Group so as to provide a more meaningful summary of AECI's impact in this area. Due to the significance of nitrous oxide emissions at AEL's nitric acid plants they are included in the footprint calculation and, furthermore, are commented on separately.

The carbon footprint has been developed with the assistance of external consultants, making use of the 2006 International Panel on Climate Change Guidelines for National Greenhouse Gas Inventories and the Greenhouse Gas Protocol's Corporate Accounting and Reporting Standards, as developed by the World Resources Institute and the World Business Council for Sustainable Development.

The term carbon footprint is commonly used to describe the total amount of CO₂ and other greenhouse gas emissions for which an organisation is responsible. The footprint developed for AECI currently includes Scope 1 emissions (direct emissions from, for example, the consumption of fuels in stationary equipment) and Scope 2 emissions (indirect emissions, which arise from the generation of the electricity consumed by the Group). Data for Scope 3 emissions (indirect emissions related to product delivery and employee business travel) are not available at present.

The organisational boundaries for which this footprint has been determined are as follows:

• AEL's Modderfontein operations, together with the footprint associated with rock-on-floor contracts;
• all Chemserve operations;
• all Heartland operations;
• STF's operations.

AECI's carbon footprint, measured in tons of CO₂ equivalent, is shown in the table below:

Emissions other than CO₂ can also have a significant impact in terms of global warming potential.

Ammonium nitrate is used extensively in the explosives and fertilizer industries and is manufactured from nitric acid and ammonia. AEL has two nitric acid plants at Modderfontein, the No. 9 and No. 11 plants. Nitrogen oxide gases are produced through the oxidation of ammonia on a platinum-rhodium metal catalyst gauze in the ammonia burners of AEL's nitric acid plants.

Most of the gas generated is in the form of nitric oxide, which is absorbed by water to form nitric acid. Some of the gas produced is in the form of nitrous oxide, which is typically released into the atmosphere as it does not have any economic value or toxicity at typical emission levels. However, it is a greenhouse gas with a global warming potential approximately 300 times per unit mass that of CO₂.

To combat global warming, a number of countries have ratified the Kyoto Protocol, thereby committing to reduce their emissions of greenhouse gases, or to engage in emissions trading were they to maintain or increase emissions of these gases.

Provision was made in the Kyoto Protocol for the registration of Clean Development Mechanism (CDM) projects, which allow participants in developing countries to generate Certified Emissions Reductions (CERs) by lowering their emissions of greenhouse gases. CERs can then be sold to those entities that are under an obligation to reduce greenhouse gases but are unable to achieve the required reductions.

AEL has registered two CDM projects with the United Nations Framework Convention on Climate Change. These are for the No. 9 and No. 11 nitric acid plants, and they were registered in November 2007 and February 2008 respectively. The projects involve the installation of secondary catalysts in the ammonia burners of the plants, below the primary gauze catalyst.

This secondary catalyst decomposes the residual nitrous oxide without affecting the production of nitric acid.

During 2009, the secondary catalyst on No. 9 nitric acid plant achieved a reduction of 50,3% in nitrous oxide emissions, with a total of 163 tons emitted; that on No. 11 plant achieved a 70% reduction, with a total of 270 tons emitted. When converted to CO₂ equivalent, this amounts to 50 500 tons and 83 700 tons respectively

The lower efficiency achieved on the No. 9 plant is as a result of it being an older, high pressure plant. It is notoriously difficult to achieve high levels of emission abatement through the use of secondary catalysts in high pressure plants. The No. 11 plant would normally have achieved a higher level of efficiency, but a cracked catalyst basket led to significant bypassing for a six week period, before operational considerations allowed the taking off line of the plant.

To place these reductions in perspective, the reduction in CO₂ equivalent emitted annually by AEL from these two plants is equivalent to the quantity of CO₂ emitted by 60 000 medium-sized cars travelling an average of 25 000km per annum.