Don't forget, the heat is also keeping the pipes unclogged. If you remove the heat a lot of the fats turn into hard mass that is extremely difficult to get rid of.
Reminds me of the story of what happened when traffic lights got "upgraded" to LED to save on energy. First winter all traffic lights got completely covered in snow and traffic ground to a halt. The "waste" heat as was not such a complete waste after all, it was continuously melting snow off the lights.
Incandescent lights still waste heat 90% of the time when there’s no snow. Adding some resistive heating to run when needed on LED lights is much preferable.
It's a story about carefully examining the differences when changing technologies and avoiding imprecise or dual use terms like "waste." This is something that should come naturally to a hackers forum, but a bit of marketing does get mixed in here from time to time, and people can't seem to help themselves from embellishing interesting new technologies into universally improved solutions.
So.. you get this back and forth between the two camps as they rush to take victory laps around each other.
It's not a new technology, though. The Vancouver system mentioned in the article has been in operation since 2010, which may be a short time in infrastructure terms, but similar systems that extract waste heat from sewage have been in commercial operation since at least the mid-1980's. The system in Vancouver is now being expanded to 9 MW of power output, but there's a similar one in Stockholm that first opened in 1986 that now has an output of 225 MW. That one uses treated wastewater though, while the one in Vancouver operates on raw sewage that hasn't hit the treatment plant yet.
District heating is at a different scale in northern Europe and especially in Scandinavia. The systems in North America are (with a few exceptions) typically local to a campus, a neighborhood or a small downtown area, serving maybe a hundred buildings with maybe tens of kilometers of pipes. The public heating utility in Stockholm alone serves 800,000 people, has over 3000 km of pipes and generates over 8,000 GWh of heat energy in a typical year. It's kind of the default way of heating most buildings, here. The main exception is single family homes where past eras of cheap electricity often made people prefer other heating methods.
Such systems don't have to be huge to be useful, but the bigger they are, the more opportunities you have to move heat from places that don't want it (data centers, industry in general, etc) to places that do.
> avoiding imprecise or dual use terms like "waste."
Reminds me of the Texas power grid failure due to being an energy market designed by ENRON (still is too!). Turns out the opposite of “efficiency” isn’t “waste” it’s “redundancy” which their design is very efficient at getting rid of.
Well, moving away from "efficiency" can take you toward redundancy, but it doesn't have to. Some waste is just wasteful. It's important not to oversimplify, otherwise you wind up with counterproductive memes like "that project is justified because it will create jobs" or "the free market is the best solution for every problem" (it's a great solution for some problems, but ignores externalities).
Unfortunately the English language makes me choose between completely conveying nuance at all times and being understood and upvoted (people prefer short and pithy over long and subtly more correct).
I agree with your followup 100%. I didn’t write it in my original as it would have watered down my main communication goal.
Whenever says something is being made more “efficient” I ask them what they are trading for what.
Reminds me of the story of what happened when traffic lights got "upgraded" to LED to save on energy. First winter all traffic lights got completely covered in snow and traffic ground to a halt. The "waste" heat as was not such a complete waste after all, it was continuously melting snow off the lights.
So, just add heating element when you need it? It's probably more efficient to use LED lights than to have incandescent light bulb for the few days of the year when you need it.
If you need to keep the heat with the wastewater, don't harvest it unless there's excess heat to be harvested.
As an amateur electronics engineer... I think we can do better. I have not checked what is the actual solution, here is what I figured out on my own:
First of all, the yellow light bulb might not be enough to reach with the heat to the red and green lights. And since it is only turned on for a brief moment, might not be providing enough heat. And will still be wasting heat when it is not needed.
Even heating it up when it is cold is a waste of time. I can only guess at the number of nines, but 99.9% of the time you can get away without heating even when it is very cold, because the conditions are not right for the snow to accumulate (read -- it is not snowing, the temperature is not close to zero degrees celcius and the wind is not blowing in the right direction).
The only time the heat is really needed is when the lights are obscured with snow.
So here is a better design: have a photo cell inside the light to detect if the light is reflected back to the photo cell. The cell is isolated from the rest of the inside but has a clear access to a small portion of the glass in front.
When snow starts accumulating on the glass, the traffic light will start getting scattered in all directions including getting reflected back inside the traffic light and into the photo cell.
You can easily discern between light from the outside from light from the traffic light by seeing if it follows the pattern. Ie. constant light from outside regardless of the light turning on or off means it could be something like a sunset shining into the light and we need not worry about it.
What we are looking for is a clear difference in light shone into the cell when the traffic light is turned off vs when it is turned on.
If I can do that there is probably other, smarter people who can figure out even better solutions.
> Tucked under a Vancouver bridge, an energy centre sits on top of the existing sewage pumping station so heat can be captured before sewage reaches the treatment plant
Seems like if they’re doing this right before a treatment plant that they’ll be able to localize the problem and hopefully handle it effectively. Though it would be more assuring if they also talked about some of possible problems.
I feel like there must be better options than resistive heating to melt the snow.
For example instead of a separate visor for each light, use a single visor that covers all three lights. And maybe angle the whole thing forwards slightly so that there isn't even a vertical surface for snow to rest on - gravity would simply cause it to fall off.
It's wild to me how they're strolling through the sewer tunnel, with the voiceover explaining how it was put under ground to shelter people from all the disease carried in it... and they're wading through it, no respirator or any other protection of the sort.
Surprisingly safe given they're neither drinking the effluent nor washing open wounds with it.
The Great British Sewer Project (version one, not the recent and ongoing rebuild) was all about safe water, the disease came from a contaminated water for drinking and washing pump and not from "the Miasma" (unseen spirit forces wafting about in dank air).
The "put underground" part was mainly about isolating waste water from washing and drinking water, reducing the stench in the air was a related benefit of course, but that wasn't the vector of infection.
Just a few minutes into the video, the reporter gets some splashback in his mouth. That direct hit aside -- there are multiple "tributaries" actively dumping waste into the main tunnel. With all this moving liquid, there's bound to be some of it aerosolized into the air, especially in an enclosed space like that.
It says in the article that it sits on an existing pumping station, so that's probably the ideal place to avoid this problem, since those pumps would often be designed to grind/mascerate the incoming sewage anyway.
This is what happens when sewage is given time to cool: https://www.youtube.com/watch?v=3i_axpk0a7Q
Reminds me of the story of what happened when traffic lights got "upgraded" to LED to save on energy. First winter all traffic lights got completely covered in snow and traffic ground to a halt. The "waste" heat as was not such a complete waste after all, it was continuously melting snow off the lights.