Hansen: The Gas Warning Inventor

The Unsung Hero Who Gave Gas Its Warning Smell

The inventor of the distinctive warning smell for natural gas, an 85-year-old scientist from Gloucestershire, is the new holder of a special lifetime achievement prize. Peter Hansen's creation is a smell so unpleasant it has saved countless lives, a legacy now celebrated by a podcast dedicated to life's more overlooked subjects.

An Honour for the Overlooked

Peter Hansen, a quietly spoken engineer, is the first person to receive a special honour presented by The Dull Man's Podcast. The show is the work of a team operating out of Gloucestershire, who decided to create the award after Mr Hansen appeared as a popular guest. His interview was featured in Episode 16, titled "Can You Smell Gas". Listeners were captivated by the story of his life-saving, yet unheralded, invention.

The podcast's co-host, Demitris Deech, explained the feedback was immediate. People wanted to know if Mr Hansen had been knighted or awarded an MBE. They asked if he held a Nobel Prize for his contribution to public safety. The answer to all these questions was no. And so, the podcast team resolved to create a prize of their own to acknowledge his significant work.

An Inventor's Pride

Mr Hansen expressed his delight and pride in receiving the very first lifetime achievement prize from The Dull Man's Podcast. The presentation took place at a special ceremony in Cirencester, not far from his home. Discussing the award with his family, he noted his surprise that many people remain unaware that the natural gas used in their homes is inherently without any smell at all. His invention provides that crucial, and now universally recognised, warning sign.

This lack of public awareness underscores the silent, vital role his work plays. Every day, millions of people are protected by a foul smell they hope never to encounter. It is a testament to an invention designed not for comfort or pleasure, but for the fundamental purpose of preventing disaster. His contribution ensures that any accidental leak is immediately obvious to the human nose.

A Call to Action in the 70s

The whole story started during the nineteen seventies. While operating his own engineering firm in southern Wales, Peter Hansen took a call. The man on the other end was from the town of Newport. The request was urgent and of national importance: a company needed him to develop a smell. This was not just any smell, but one to be added to the country's burgeoning supply of natural gas.

Britain was in the midst of a massive energy transition. The discovery of large gas fields in the North Sea during the 1960s prompted a nationwide switch from "town gas" to the new fuel. Engineers were building a massive new pipeline. It stretched from coastal terminals to industrial centres, including the steel works at Newport and continuing toward the Midlands for distribution. This new fuel source had a critical flaw: it was completely odourless.

Image Credit - BBC

A Nation Switching Fuel

The conversion from manufactured town gas to North Sea natural gas was one of the largest peacetime operations in the UK's history. Between 1967 and 1977, this colossal engineering project involved converting around 40 million appliances in 14 million homes and businesses. Town gas, produced from coal, was toxic and contained carbon monoxide, but it had a distinctive smell. The new, cleaner natural gas was non-toxic, but its lack of odour made it a hidden danger.

An undetected leak of the highly flammable natural gas could lead to a catastrophic explosion if it encountered a simple spark or naked flame. The government-led programme to switch fuels made the creation of an artificial warning scent a national priority. The urgency conveyed in the telephone call to Mr Hansen reflected the scale of this risk as the new gas network expanded rapidly throughout the nation.

The Spectre of Past Tragedies

The urgency to odorise natural gas was rooted in a history of devastating accidents. The most infamous of these occurred decades earlier in the United States. On March 18, 1937, a massive explosion destroyed the New London Consolidated School in Texas, killing nearly 300 students and teachers. An investigation revealed the cause was an undetected leak of odourless natural gas, which had been ignited by a spark from an electric sander.

This horrific event served as a catalyst for safety regulations worldwide. Texas quickly passed a law mandating that a malodorant be added to all natural gas to make leaks detectable by smell. The tragedy highlighted the immense danger of distributing an odourless, combustible gas. It was this hard-won lesson that informed the serious and urgent nature of the task presented to Peter Hansen during that decade.

The Chemical Conundrum

The challenge required finding a substance with a uniquely powerful and unpleasant smell. Natural gas itself is mostly methane, a colourless and odourless hydrocarbon. The ideal additive needed to be detectable in tiny quantities but not interfere with the gas's properties. The solution lay in a class of organic sulphur compounds known as mercaptans, or thiols.

These chemicals, responsible for the smell of rotting meat and skunk spray, are notoriously foul. In Britain, the standard substance used to give natural gas its smell is a blend including tertiary-butyl mercaptan (TBM) and dimethyl sulphide. During the nineteen seventies, Mr Hansen had to identify a chemical formula that would provide an unmistakable warning.

Designing a Horrible Smell

Peter Hansen's mission was clear: he had to find the most repulsive scent he could imagine. He acknowledged that this was his primary selection criterion. The result was a smell he describes simply as "horrible," and one he finds difficult to articulate in words. This deliberate unpleasantness is the core of the invention's success as a safety feature.

The chosen chemical had to meet stringent criteria beyond just its foul odour. It needed to be chemically stable, non-corrosive to pipelines, and burn away completely and harmlessly with the gas. Most importantly, the human nose needed to be able to detect it at concentrations far below the lower explosive limit of natural gas, providing a wide margin for safety.

Image Credit - BBC

From Concept to Reality

After developing his formula, Mr Hansen sent samples of the potent compound from his own new enterprise to the gas provider. His creation met their requirements, successfully imparting a distinct and alarming smell to the otherwise undetectable gas. The science and formulation had proven successful, but this initial triumph quickly led to a much larger logistical challenge for the burgeoning entrepreneur.

The successful samples demonstrated the viability of his invention. The scent was precisely what the industry needed to ensure public safety as the national conversion programme gathered pace. However, proving the concept was one thing; producing the odorant on an industrial scale was a completely different and more daunting proposition for his small enterprise.

The Milford Haven Connection

The newly developed scent was destined for the Milford Haven refineries located in Wales. This deepwater port became a crucial hub for the UK's energy industry in the 20th century. Major oil refineries were built there, and it eventually became home to the UK's largest Liquefied Natural Gas (LNG) terminal. Natural gas, a plentiful by-product from the North Sea oilfields, was brought ashore at these terminals.

It was at these massive industrial sites that the odorant would be infused into the fuel supply before it entered the national distribution pipeline. This strategic location ensured that all gas flowing out to homes and businesses nationwide would carry the vital, life-saving scent that Peter Hansen had created. The port was the gateway for Britain's new energy source, and the point of application for its most important safety feature.

An Overwhelming Order

With the formula approved, Mr Hansen faced a significant hurdle. The gas provider placed an order for 40,000 litres. They required delivery inside a strict two-month window. For what he called his 'fledgling company,' this was an immense volume. He calculated that producing such a quantity would normally take him an entire year. The urgent national need had placed enormous pressure on his small operation.

The scale of the order highlighted the speed and scope of the national gas conversion project. The demand for the odorant was immediate and vast, far exceeding the capacity of a small, newly established business. This mismatch between demand and production capability presented a critical problem that threatened to derail his involvement in the project.

A Partnership Falters

To meet the daunting production target, Mr Hansen entered into a partnership with an acquaintance who owned a business in Bristol. This collaboration was a practical solution to the immense manufacturing challenge he faced. For a time, they worked together to produce the large quantities of odorant that the gas provider required.

However, this arrangement proved to be short-lived. His friend's business ultimately failed and went into liquidation. This unforeseen collapse left Mr Hansen once again without the means to fulfil the massive order on his own. He had to pivot his strategy quickly to ensure the critical safety substance still reached the national gas grid.

A Deal Built on Trust

Following the failure of his production partnership, Peter Hansen made a pivotal decision. He opted to sell his chemical formula for the odorant straight to the gas provider. Reflecting on the period, he acknowledges that, being in his thirties, he lacked significant business experience. He admits he should have secured the terms of the sale in a formal written contract.

Instead, the entire transaction proceeded based on mutual trust. There was no legally binding paperwork to formalise the agreement. While this might seem naive from a modern business perspective, it was a pragmatic solution at the time. The sale ensured that the vital odorant could be produced at the required scale without further delay, fulfilling the project's urgent safety mandate.

The Kudos of Creation

Despite the lack of a formal, and potentially more lucrative, written contract, Mr Hansen harbours no regrets. He states that the "kudos" of having delivered the essential smell was sufficient reward for him. The personal satisfaction and professional recognition he gained from inventing the solution to such a critical national problem was what mattered most.

This perspective highlights his focus on the engineering challenge and the public good rather than on commercial gain. His pride comes from the knowledge that his invention has protected thousands, if not millions, of lives across the United Kingdom. The legacy of his work is not in a patent portfolio, but in the silent, smelly guardian present in every gas-supplied home.

The Science of Odorisation

The process of adding the scent to the fuel is known as odorisation. It is a precise science, typically carried out using specialised odorant injection systems. These devices introduce tiny, carefully measured amounts of the liquid odorant into the high-pressure gas stream. The goal is to ensure the gas is detectable by a person with a normal sense of smell when it reaches just one-fifth of its lower explosive limit in the air.

Modern systems use sophisticated programmable logic controllers (PLCs) that monitor the gas flow and automatically adjust the injection rate. Some systems use a precision drip technology, where an optical sensor counts individual droplets of odorant to ensure accurate dosing. The entire process is designed to be consistent and reliable, maintaining public safety across the vast network.

The Power of the Human Nose

The choice of sulphur-based mercaptans as an odorant is directly linked to the incredible sensitivity of the human olfactory system. Our noses can detect these compounds at incredibly low concentrations, sometimes as low as a few parts per billion molecules of air. This is possible because of specific odorant receptors in the nose that are highly tuned to these molecules.

Interestingly, research suggests the element copper plays a role in our ability to respond to gas odorants like tert-butylthiol. This exquisite sensitivity makes mercaptans the perfect warning signal. Even a very small leak will release enough of the odorant to be immediately noticeable, long before the gas concentration becomes dangerous. This biological fact is the foundation upon which modern gas safety is built.

Modern Safety Standards

In the United Kingdom, gas safety is rigorously managed under regulations enforced by the Health and Safety Executive (HSE). The Gas Safety (Installation and Use) Regulations 1998 provide the legal framework for the safe installation, maintenance, and use of gas appliances and systems in homes and workplaces. These rules mandate that all work on gas systems must be carried out by a competent and registered professional.

Since 2009, engineers must be on the Gas Safe Register, the official list of businesses legally permitted to conduct gas work. Landlords have a legal duty to perform annual safety checks on all gas appliances and flues, with certificates issued to tenants. These layers of regulation, built upon the fundamental safety net of odorisation, work together to prevent accidents and protect the public.

A Wider Application

The principle of adding a scent to a dangerous, odourless gas is not limited to the natural gas that flows into homes. The technology is also critical for Liquefied Petroleum Gas (LPG), commonly used in portable canisters for camping and outdoor cooking, as well as for heating in areas off the main gas grid. Propane and butane are likewise odourless and require an additive.

Different chemicals are sometimes used; for instance, ethanethiol is often added to LPG, which is why its smell can be distinct from that of natural gas. As energy systems evolve, odorisation is even being adapted for new fuels. Projects are underway to ensure that hydrogen, when blended into the fuel grid or used on its own, is also odorised to maintain the same level of public safety.

The Philosophy of the 'Dull'

The prize presented by The Dull Man's Podcast brings Peter Hansen's story full circle. The podcast's ethos is to celebrate the mundane, the overlooked, and the quietly essential aspects of life. It finds fascination in the subjects that might otherwise be considered "dull." By honouring Mr Hansen, the show elevates a perfect example of its philosophy: an invention that is ubiquitous, critically important, yet almost entirely taken for granted.

His creation is not glamorous. Its sole purpose is to be horrible. Yet, in its deliberate unpleasantness lies its profound importance. The award highlights the idea that some of the most significant contributions to society are not headline-grabbing feats, but the steady, reliable, and often invisible systems that keep us safe every day.

A Legacy of Silent Safety

Peter Hansen's contribution to public safety is immense, even if it is not widely known. His quest during the nineteen seventies to find the most repulsive odor resulted in a warning system that has undoubtedly prevented countless fires, explosions, and fatalities. It is a quiet legacy, measured not in accolades or financial return, but in the accidents that never happened.

The first-ever lifetime achievement prize from a podcast celebrating the "dull" is a fitting tribute. It recognises a hero whose ingenuity has become an invisible, yet indispensable, part of modern life. Thanks to his work, a simple, foul smell serves as a constant, silent protector, proving that sometimes the most important inventions are the ones we hope we never have to notice.