Vector reduces ‘fugitive emissions’ from its network

Detecting gas leaks using SELMA (Street Evaluating Laser Methane Assessment)

Small gas leaks are a normal feature of any gas distribution network. While Vector’s gas network performs better than the New Zealand average for public reported escapes, the leaks that do happen are a contributing factor to reported greenhouse gas emissions.

Vector reduced its scope 1 greenhouse gas emissions by 13 percent from its 2020 baseline with scope 1 emissions for the 2023 financial year calculated at the equivalent of 19,485 tonnes of carbon dioxide - down from 21,816 tonnes in the previous year.

Vector credits this in large part to the work it has been doing to reduce ‘fugitive emissions’ from its gas pipelines. By creating a fluid-dynamic model of the gas network, Vector can identify events that release the most emissions.

Small leaks that go undetected for long periods of time were found to be the largest culprit. For example, two leaks detected in one year alone released the equivalent of over 3,000 tonnes of carbon dioxide, Vector says.  

With 4650 kilometres of main pipelines in Auckland and more than 119,000 connection points – Vector is planning to increase the frequency of its pipeline surveys to every six months.

This reduces its average leak duration from six to three months, the company says.

Since 2016, Vector has partnered with Omexom, the New Zealand arm of a global energy infrastructure services group, to detect a gas leaks using a system known as SELMA (Street Evaluating Laser Methane Assessment).

The equipment is fitted to a ute and detects minor gas leaks by simply driving down the street at normal speed. Featuring two independent detectors, SELMA detects leaks from both the front bumper intake system and the rooftop camera.

A precision gas analyser on the front bumper uses a number of small plastic tubes to sample air in the immediate vicinity, while a remote laser on the roof scans for leaks within a radius of up to 150 metres.

Air drawn in via the front bumper detector is filtered between two reflecting mirrors to analyse the sample. When a gas leak is detected, an alarm is activated, and GPS technology marks the exact location so it can be relayed to the reactive maintenance team for immediate investigation.

Proactive pipeline surveying like this is part of Vector’s approach to ensuring public safety, while also contributing to its emissions abatement strategy. This identifies opportunities to reduce emissions and the corresponding cost or saving of doing so.

In the of case pipeline surveying, Vector has found that, in addition to the public safety benefits, increasing the frequency of pipeline surveying also reduces emissions and saves costs.

“In 2021, we increased survey frequency from two yearly to yearly. This has to date reduced annual emissions in this category by 37%, or 4,013 tCO2 e, compared to our 2020 baseline.

“In 2024, we intend to further increase pipeline surveys to six monthly, which will enable us to find leaks even faster and reduce reported faults.

“As a result of these activities, we are maintaining a downward trajectory on these emissions,” Vector says.