July 10, 2017

Continuous emissions monitoring in a climate-friendly state

By Nate Buell, Marketing Communications Leader, Cytiva

California’s wave of change: continuous emissions monitoring in a climate-friendly state.

California leads the way

The attitude of the international community towards global warming is changing. As more countries join the pledge to actively change and maintain global temperatures, they are looking to California for guidance.

The American state is well known as an environmental policy advocate and leader. With a commitment to cleaning up the environment spanning over 30 years, California has shown policy makers that it is possible to achieve lower greenhouse gas (GHG) emissions by implementing systems that encourage private sector collaboration.

Incentives for keeping emissions low

In 2012, the state launched its Cap and Trade (CT) Program, which sets an annual cap on the level of GHGs emitted within the region. This cap is divided up into allowances that companies emitting GHGs can obtain free of charge or via an auction. If a company receives an allowance that exceeds its GHG emissions, it has the option to sell this excess to another company or to save it. However, if a company’s GHG emissions exceed its set allowance, the company will be penalized.

The CT program aims to reduce California’s GHG emissions to 40% of its 1990 levels by 2030. With a 10% reduction in CO2 emissions from 2004 to 2015 – 3% above its 2020 goal – and the generation of over $4 billion from reductions in CO2 emissions alone, the state is on track to achieving this goal. The entity responsible for the successful implementation of the program is the California Air Resources Board (ARB).

Every year, the ARB requires each California company that emits GHGs to submit its emissions offset for the previous year, to demonstrate that it has stayed within its allowance. The submitted results are derived from stack emissions tests performed by an engineer that the company hires.

Tests and Confirmation

Steve is a contracted air quality engineer, working for a fictitious large oil refinery in Southern California. The fuels and gases produced by his employer’s refinery are formed using extreme heat, separating raw crude oil into different fractions. This process releases several GHGs into the atmosphere.

To monitor the gases emitted, the refinery has installed a continuous emissions monitoring system (CEMS) within its flue stacks. In a continuous dry basis gas emissions monitoring test, the system extracts a sample of the gas from the stack through a sampling probe. The collected gas then flows through a heater filter, which separates it from any particulates that could corrupt the test readings.

After the gas has been filtered, it makes its way through the CEMS’s condenser, where its remaining moisture is removed. This process further clarifies the gas before it flows through to the gas analyzer, where the concentrations of the gases are measured and recorded.


Fig 1. Simplified diagram for a continuous dry basis gas emissions monitoring test.

Due to the extreme nature of the environment within the refinery’s stacks, Steve prefers to use quartz fiber filters. These filters’ ability to eliminate the formation of artefact products from sulfates, nitrates, and other heavy metals is important to Steve, because it helps to ensure that the refinery’s CEMS results are consistently accurate. This consistency is vital, as every year these tests are observed by one of the ARB’s expert consultants such as Allison.

Allison’s job is to verify that the results submitted to the ARB are as accurate and representative as possible. During the test, she observes Steve’s methodology and the mechanics of the refinery’s CEMS, recording the results as the test progresses. After she is confident that the results are illustrative of the refinery’s pollution level, Allison sends over a final report detailing whether or not the refinery is in compliance with its allowance.

The future of emission controls

The sophistication of California’s policy, as well as policies from other states, has inspired many countries, such as Canada, Mexico, and Peru, to sign the Under 2 MOU agreement. This initiative was spearheaded by Californian Governor Jerry Brown. Brown also instilled confidence in his home state, when in 2017 the CT program was granted a 10-year extension.

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