- You have to size your cooling towers for your hottest hour. Doing this saves you no capital costs.
- You barely have to run the fans on your cooling towers in the winter because the air is so cold. So often this also won’t save you much operating costs.
- Already there is an essentially unlimited amount of so called “waste heat” from power plants and factories. Building district heating systems is extremely capital intensive, which is why this isn’t done more.
- As a municipality it’s just a horrible idea to make the heating system of your whole city rely on a random company continuing to operate (even worse if said company is in a potential bubble). This is why most district heating systems work with power plants - they already have the government involved in ensuring their continuing operations.
I don't think I ever said it reduced capital cost. I agree (though you might be willing to take more risk on reducing redundancy e.g instead of 2+1 cooling towers you may be more willing to just buy 2).
You cannot put a power station in the middle of a city centre, you can put a datacentre there. The main reason this isn't done more is that it's expensive to build heat network between the 'far out of town industrial area' where they put the heat sources and the city centre where the heat consumers are.
I don't know why a municipality is involved, but regardless you can simply install a backup heat source and/or add a mix of heat suppliers to the network. Backup gas boiler or similar is not that problematic or expensive to add particularly because you don't need to add redundancy as it's just there for a backup scenario.
Wellbutrin can/should(?) be taken indefinitely and there's nothing wrong with that, it doesn't pose big long term health risks. As I understand it the issue is with SSRIs (they do pose health risks, obviously there's nothing wrong with taking them if it is a net positive for you).
Hell knows they've got the budget for it, as last year Republicans voted to give them more money than many foreign militaries, and more than all other Federal law enforcement combined.
To hear Patrick Collison tell it, "we see that one of the main limits on Stripe's growth is the number of successful startups in the world. If we can cheaply help increase that number, it makes a lot of business sense for us to do so."
The J.C.R. Licklider book was difficult for me just because the font is small. I ended up finding an epub version and read that instead and loved it. The physical book is beautiful though and I'm glad I have it.
>Does Aerolamp produce ozone?
>Yes - but only a very small amount
>Typical indoor ozone levels are 4-6 parts per billions (ppb), while average levels of outdoor ozone are 20-30 ppb - almost all indoor ozone comes from outdoors. Most likely, you will raise your indoor ozone levels much more by opening a window than by operating a far-UVC lamp.
>It's true that in a sealed chamber in a lab, typical far-UVC installations might produce significant (10s of ppb) ozone. However, our indoor spaces aren't sealed chambers. Both theoretical predictions and experimental evidence suggest that Aerolamp will raise indoor ozone levels by no more than 1-2 ppb. Expected ozone increase can also be simulated with Illuminate.
>However, we recognize that ozone is a pollutant, and recommend that Aerolamp should be used with portable air cleaners which include an activated carbon filter. Studies suggest that a single activated carbon filter is more than sufficient to mitigate any far-UVC derived ozone.
I agree that the filter thing doesn't make sense, but it does not seem like this product would meaningfully increase your ozone exposure.
Yes, you can point this specific UV wavelength at your skin and be fine. People have done extensive animal trials and it is not carcinogenic. Many people have been exposed to a lot of far UVC and nothing bad has happened to them.
Looking right at it might not be good for your eyes.
I feel confident for myself that far UVC is safe.
However, the environments I'd want to use this in are those where many people are gathered. I am not sure whether it is respectful/socially good to use this in those situations (given that far UVC products are not subject to any special regulatory review).
Edit for some additional thoughts:
How does this compare to a air filter?
Pros of UV:
- You are helping support R&D for this very important technology
- Even this Aerolamp DevKit is going to be more cost effective at addressing certain pathogens which are highly susceptible to UV, such as COVID. My guesstimate is that the highest capacity/$ off the shelf air purifier you can buy (https://www.cleanairkits.com/products/brisk-box-ultra-black) has about a third to half of the COVID-removing capacity/$ vs. the Aerolamp DevKit. Ditto for energy efficiency.
- Less maintenance vs. an air filter
- Quietest option
Cons of UV:
- Less energy and cost effective at addressing other microbes, particularly mold
- No ability to address dust, another very important air quality issue
The results of the study showed that far-UVC irradiation causes significant color degradation (∆E00 >5) in all the polymeric materials tested, after 290 J/cm2 radiant exposure. In addition, significant changes in mechanical properties were observed when evaluating elasticity modulus, elongation at ultimate strength, elongation at break, and tensile strength. A particularly large decrease in elongation at break (up to 26%) was observed in fiber-reinforced composite materials.
Is there anything that suggests this will turn out okay?
I don't think "stop using polymers in any place where far-uvc may exist" would fly. So it's cool that we've made something that isn't going to hurt humans, but if it destroys the stuff humans depend on, not sure that works either?
I also don't think the world is going to move to UV-stable polymers for everything just to make far-UVC work (in some cases this isn't even possible). We almost always just make things more UV-resistant instead of UV-stable.
Yes, it may not be good. However, that study used thin material samples - and those are particularly vulnerable to UV. Thicker materials are more resistant because the UV doesn't penetrate into them.
If you want to deploy UV in a specific space (think conference room or hospital ward), I don't think the problem is that hard. There are coatings you can put on top of existing plastics which protect them from UV light. However, I imagine that customer education around managing risk to plastics is going to be a key issue for UV companies if they are to succeed.
This is fair - but i think you are undershooting what is normally thought of as plastics - because it includes most coatings. So the stuff sprayed on your cabinets, rolled onto your floor, paint on walls, etc, are all polymers of various sorts that are not uv stable.
The average dry film thickness of these things is going to be a few mils total (~100% will be 2-6 mils). So very thin.
Pretty much any indoor coating is not going to resist UV well, whether it yellows or not. The acrylic based resins i guess will be okay. The reason all the lights in houses are UV filtered is not entirely about safety - the amount of UV radiation they would produce is fairly miniscule from a human perspective - but if they weren't filtered, leaving the lights on in your kitchen too often would likely, over the course of five years, be really bad for the cabinets, floors, walls, etc.
I think this in practice, the killer. Even if you could deal with plastics themselves, there is just so much you will now have to protect or change.
> Yes, you can point this specific UV wavelength at your skin and be fine.
Not so sure about that: there are microbes on our skin, protecting us from harmful bacteria, funghi and viruses. This lamp would kill those friendly microbes.
It seems a better idea is to put this UV lamp in a duct, and treat only the air that passes through.
Not really. Those microbes live deep in your pores where the UV wouldn't reach. Even if the UV totally scoured the surface of your skin, it would only be a temporary disruption, which we're generally ok with. After all lots of things disrupt the skin microbiome--showering, hand sanitizer (which DOES penetrate into the pores).
But I think UV skin microbiome disruption is likely to be pretty mild compared to things like eg hand sanitizer. Generally anything that lives on a surface (compared to liquid, and especially air) requires a much higher UV dose to inactivate, because even seemingly-smooth surfaces actually have lots of microscopic nooks and crannies for pathogens to hide in. And skin isn't smooth at all--it's got tons of visible wrinkles and surface complications and complicated geometry. Bacteria are also less sensitive to far-UV than viruses. So lamps that are dose calibrated to kill airborne viruses aren't going to have much of an effect on bacteria that live on a complex surface.
There's actually some data on this although sadly it never ended up published--my lab collected microbiome data for this 66 week hairless mouse skin exposure study https://pmc.ncbi.nlm.nih.gov/articles/PMC9691791/ and found basically no difference in microbiome between the exposed and unexposed mice. It didn't end up in the paper because nobody in the lab had enough bioinformatics expertise to do a nice publishable analysis and just had to take the bioinformatics centers' word on it that there weren't significant differences. Weak/hearsay-ish evidence but not nothing!
In-duct UV is a thing but it's really not ideal for preventing person-to-person disease transmission, for a number of reasons.
> Many people have been exposed to a lot of far UVC and nothing bad has happened to them.
>
> Looking right at it might not be good for your eyes.
>
> I feel confident for myself that far UVC is safe.
This is dangerous misinformation. Like any toxic, it's the Dosis that kills
There are very powerful far UVC products available which will give you sunburn on your skin in a couple of seconds
Somebody blasting UVC in a room of people is crypto monkey level of stupid
Far UVC is carcinogenic when it reaches living tissue. However, it has a very short mean free path so it doesn't, generally, reach the growing layer of skin. It's less obvious whether exposed mucus membranes (lips, nose, tongue) or the eyes are affected. It probably doesn't reach the lens of the eye, which is good.
The tear layer only contributes a little bit--far-UV eye safety is mostly down to the fact that the 222nm only penetrates to outer epithelium (so cells that will be dead in a few days anyway), and the fact that your eyes get very little effective dose if you aren't staring directly into the lamp. You've got eyelids, eyelashes, eyebrows, hair, etc, so the effective dose to your eyes is actually much lower than the dose assumed by most safety standards (ANSI/IES 27.1-22, UL8802), which are fairly conservative. Check out this paper http://onlinelibrary.wiley.com/doi/abs/10.1111/php.13671
That is not true. It can cause possibly eye irritation but animal trials have shown that it is not carcinogenic even to mucus membranes, eyes, and thin-skinned areas.
The advantage of far UVC over other UV air cleaning solutions is that it doesn't need to be ducted. This means that you can kill microbes right when they leave someone's mouth - you don't need to wait for them to be sucked through an air handler.
I'm curious if plastics embrittlement is a problem with Far-UVC. I recently was putting a large evaporative humidifier [1] through its paces for someone to get my opinion, and a challenge was that you had to clean the water tank that was the foundation of the unit fairly frequently (every few days). I provided feedback to the manufacturer that a far UVC bulb in the tank might be useful for reducing cleaning intervals.
For use cases where the emissions are contained (HVAC, water tanks, etc), I think it's a slam dunk from an electronic antiseptic perspective. UV is somewhat common in water filtration today, but perhaps an improvement is possible if these bulbs last longer than existing UV solutions.
(I do not recommend the humidifier by the way, simply too much work to keep the water tank and the evaporation panels clean, I recommend an ultrasonic version instead)
This is a study of the Ushio Care222 unit, but its underlying physics is the same as any other KrCl excimer lamp, so its pretty implausible for other KrCl lamps to exhibit spectral drift when this one doesn't.
The spectrum does change a bit over time--it actually gets less dangerous. But it's a very slight difference.
So different hardware, a clinical unit designed for thousands of hours.
Vs a very likely Shenzen unit that a teeny tiny group is selling on a basic website. And, you can make zero claims on whether a light spectrum of a led will go up or down over time despite one example. Amplifiers/voltages, coatings wearing down, oxide layers in diodes breaking down, etc.
I'm not sure what you mean by clinical unit--the ushio care222 is the longest lasting KrCl emitter I'm aware of, but as all bulbs age, they tend to degrade just by losing output, not by spectral shifting.
Basically everyone in far-UVC is a teeny tiny group selling lamps on basic websites, even those who source care222 emitters from USHIO. It's not a big industry!
We don't source our KrCl bulbs from Shenzen, but not for this reason. Yes, that's true about LEDs, but the physics of LEDs and excimer bulbs are different. Excimer spectra don't smoothly shift the way LED spectra do. Excimer spectra have characteristic peaks based on the energy levels of the possible gas molecule species present in the filler gas. The main change over time is the gradual reduction of the 259nm Cl2* peak, which is the main peak of concern--so it fails gracefully.
Another possibility is the degradation of the dichroic filter coating under thermal stress--but I've only ever observed this in diffused units, none where the filtered glass is open to the air, and that will happen even on an Ushio bulb.
Nukit is our competitor but I doubt very much that any concerning spectral shift will take place over the course of the lifetime of their lamp.
So… you can’t prove that the unit will not shift wavelength into a harmful range. However, I can prove that by not subjecting myself any others to claimed-harmless light that I can prove it will not become be realized to be harmful.
Cool! You missed peak covid hysteria. But, there are people that will never recover/realize. Like the type of lunatic that would subject everyone to one of these for a thanksgiving dinner in 2025.
Shrug. Nothing is 'harmless', including far-uv. Going outside in the sunshine isn't harmless. The stove in your kitchen isn't harmless. Can you prove your stove isn't going to explode some day and kill you? No, but you don't expect it to, in part because it complies with consensus product safety standards--germicidal UV products have their own standard, UL8802.
Far-uv is relatively new tech so it's reasonable to be wary, but I'm persuaded on the merits of evidence. Viruses definitely aren't harmless, and I'd rather not be catching random bugs on the regular if I can avoid it, or worry about my grandma catching flu in the hospital. Everyone has to make reasonable tradeoffs about risks and benefits.
- You have to size your cooling towers for your hottest hour. Doing this saves you no capital costs.
- You barely have to run the fans on your cooling towers in the winter because the air is so cold. So often this also won’t save you much operating costs.
- Already there is an essentially unlimited amount of so called “waste heat” from power plants and factories. Building district heating systems is extremely capital intensive, which is why this isn’t done more.
- As a municipality it’s just a horrible idea to make the heating system of your whole city rely on a random company continuing to operate (even worse if said company is in a potential bubble). This is why most district heating systems work with power plants - they already have the government involved in ensuring their continuing operations.
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