RE: [cdn-nucl-l] Natural gas and greenhouse gas production

Morgan:

I may be able to offer a bit of information based on my own limited experience. I don't really have answers to your questions, but I have related knowledge. I believe that while protecting the meters is important, the supply lines pose the greatest threat in some areas. When I was working in Toronto for a geotechnical engineering company, we would get service locates prior to performing subsurface drilling investigations. The gas lines proved difficult on occasion to locate because they tended to be fibreglass. Makes sense because fibreglass doesn't corrode, but one job (prior to my arrival) the drillers nicked one (just caught the side of the line) and a few streets had to be closed off to repair the line to stem the subsequent leak. In hindsight, a more robust material would have been a better choice for the line. Speaking of meters, I have seen bollards and the like used in front of meters on commercial/industrial establishment, but I somehow doubt that your average homeowner would go for having a few bollards in front of their house. Another NIMBY (or even NIMFY) scenario...

The second point, and this goes back to my university days so I might have it mixed up, is about your question of losses in Canada's distribution system. In an environmental chemistry class in 2nd year, we learned of a large methane pipeline that operated in the former USSR and effectively supplied gas to the entire Union. As I recall, global methane emissions actually went down after the collapse of the USSR as this pipeline's use was discontinued at that time. As I understand it, it leaked like a sieve.

Last night I went to check on the natural gas meter. I heard a hiss and found a leak in the junction from the supply line to the meter. I called the gas company and they sent someone out to fix it. The repairman told me that the o-rings fail - he was able to tighten the junction and stop the leak, though often the fitting bottoms out and one can't tighten it further (the fittings are designed so you can't crush the o-ring). If an o-ring needs replacement, another specialized crew comes and replaces it on the fly, i.e. with the natural gas not shut off they undo the junction, replace the o-ring and replace the junction. To replace a meter they dig up part of the line and crimp it closed. Incredibly crude - there is no shut-off valve on the line to my house, unlike a water line.

Since the leak was on the supply side of the meter, I haven't been paying for the gas that has been wasted. That's the least of my worries - my primary concern is the safety of my family and house around the #$%^%$3 stuff! Thankfully, the meter is in an open area at the side of the house away from the entrances, though it is close to a fresh air intake. The fitting had turned black - the repairman told me it indicated it had been leaking for some time.

1) How safe are all these home natural gas systems? What if the meter had been in a more enclosed space between houses in a city environment (i.e. close-packed housing)? Apparently these leaks are not uncommon, and are often caused by ground heavage in the winter. Or people hitting the lines with lawnmowers in the summer. Why aren't the meters better protected against damage?

2) Methane is the primary constituent of natural gas. Methane has a greenhouse gas factor over 10 times that of CO2 (as much as 20 times?). Aside from the safety aspect, what is the impact of leaking natural gas systems? What are the losses in Canada's nat gas systems? I recall a claim that in the UK the leaks counteracted any environmental benefit from burning natural gas instead of coal (the CO2 production in a nat gas fired power plant is in the order of 55% of that from an equivalent output coal plant, I recall). Note that the UK distribution infrastructure is older and therefore in (probably) worse shape than Canada's.