Why is a retracting mast preferable to a freestanding rig with, e.g. a roller furling main or a nonsuch style wishbone boom? Is there a physics reason or is this a pragmatic trade-off to fit under bridges and stay out of the way during loading?
Typically attempts to fit sails on moderns ships (like the rotor sails that have been installed on some ships in recent years) are targeted at ferries or tankers, exactly because of the loading/unloading topic. Putting large structures on a container ship will interfere with the cranes. And the SC Connector launched in 2021 can tilt the rotor to fit under bridges, with sails half as high as what OutSail tries to do [1]
Retraction is pragmatic: Air draft and loading/unloading concerns.
Wings because they perform much better than traditional sails when installed on ships that are already powering forward at speed.
Animals in general are only a tiny sliver of life on this planet. What most people think of as 'nature' i.e. large animals that a child can name are vastly outweighed each by worms, molluscs, bacteria, insects, and of course -- by a couple orders of magnitude -- plants.
Thanks for that. Now can we please break down the arthropods into spiders and non-spiders so you can alleviate my fear that spiders rule over us on this planet.
My fear of spiders is valid- all I'm saying. There must have been some bad shit in our history to instill such a fear into us..
>The report projected that the United States would have a cumulative total of 7.5 to 10 million metric tons of solar panel waste in 2050.
This compares to 292 million tons of total landfill waste in 2018 alone [1], putting solar panel waste on the order of 0.1% of total waste produced in the US between now and 2050.
There's a huge differential when it comes to processing different panel types, such as First Solar's CdTe panels (cadmium is a toxic heavy metal) versus the monocrystalline silicon panels that China is making (apparently only China has managed to scale up monocrystalline silicon, with the machines as tightly held secrets as ASML's EUV systems).
You'd think that would be a primary point of discussion in any article on solar panel waste, but no.
That is because CdTe is actually a stable molecule that isn’t water soluble, turns out the problem of panels from a toxic leeching perspective is largely from the small amounts of lead used at soldering points which is a common point with most silicon PV panels.
No reason tin can’t be used instead/lead free panels can’t be made except for the saving of a few pennies by skimping on the solder - no regulations to ensure they should be lead free. Unfortunately waste processing decades into the future isn’t often accounted for and those few pennies at design time add up across hundreds of thousands of panels on a single site…
Also, typical lead-free solders oxidize in air at their soldering temperature much more readily than near-eutectic Pb-Sn at its respective soldering temp.
That oxide film tends to interfere pretty badly with wetting of surfaces being soldered. In other words - it's much easier to end up with a "dry" joint - even with adequately increased temperature - unless better and/or more flux is used.
Not doubting the facts you've mentioned, but in my experience I've had no problems getting the surfaces to wet, though that may just be due to using rosin core solder that happens to have a good flux in it.
In Australia we generate 12 million metric tons of coal fly ash per year. It's our largest single waste stream, literally almost 1/5 of all waste generated in the country [1]. I'm sure in the US at least that amount is generated from coal. So 10 million tonnes of cumulative waste from solar panels is not huge in comparison (and this is before even considering the CO₂, NOx, SOx, etc. emissions from that coal)...
And banana plantations (or granite mountains, or the sun) are more radioactive than both because you have a lot of bananas with weak radioactivity each one, but the sum of all bananas in fruit shops is not how we measure radioactivity danger.
Coal is accumulated and relatively low, nuclear is concentrated and can reach several orders of magnitude more. Really, is not so useful to compare both cases except for whataboutism.
> Coal is accumulated and relatively low, nuclear is concentrated and can reach several orders of magnitude more. Really, is not so useful to compare both cases except for whataboutism.
That's nice but you still have to wear a dosimeter around fly ash.
And to give some further context to the over-inflated 10M tons of solar panel waste stat (over 30 years), our carbon emissions from fossil fuels are about 570M tons per year into the atmosphere. That doesn't count all the equipment used for extraction of fossil fuels, all the massive amounts of toxic waste water that comes with fossil fuel extraction, all the ash from coal, etc.
Which is to say, all the concern, even on inflated numbers, was FUD and a distraction from real problems.
or actual malice from the bad actors paid for by the fossil fuel companies to spread distrust in the transition to a more sustainable clean energy system.
Proportion of total is interesting, but less interesting IMO then comparison with other energy producers. Kinda like how we have kWh per square km, would be nice to have kWh per X and Y unit of waste.
I've been on the other side as a buyer. Although I work with 'main street' companies, not high tech, I think there's a lot of generalizable lessons. One thing to keep in mind is that some buyers have substantially all of their eggs in your basket and others will constantly have multiple deals in the pipeline. When you enter into the LOI phase with someone, you want them to be very motivated to close in order to make the time / disclosure / trade secrets risk worth it, so I would encourage sellers to attempt to enter LOI only with motivated buyers that have a high likelihood of closing the deal. A few hallmarks of motivated buyers per my experience:
- The buyer will also be the CEO: the more the buyer looks like he/she will package your business up and pass it along, the lower the likelihood that they close (and the worse your earn out is likely to perform)
- Good buyer / company fit: similar to point one, do not let people tell you they can run this company. Grill them just like you would if you were hiring a CEO to replace yourself. Buyer / company fit is huge and when they say 'the owner is too important to the company' what they often mean is 'I don't think I can run this well'. Someone who knows and is building a portfolio in your space will often be a better buyer than someone looking for 'diversification'.
- Avoid tire kickers: Background in your space is good, but being a competitor to you is bad. If they could potentially gain valuable insider information as part of diligence, be wary of moving forward.
- Small team size: smaller firms have less in the pipeline and more motivation to close on the deal in front of them. Remember that they have the same KPI (IRR primarily) and runway problems that startups have. For them, no company = no ROI.
- Ensure they're well funded: The caveat to the above is that small teams or solo buyers may not have the funds lined up, so be very sure that they actually have the investors / NW to buy the business before moving forward.
Plenty of electric scooters have no mechanical brakes and only electric braking on one hub. But since an extra couple feet of stopping power can be a life or death feature, you definitely want breaking on both tires. Even assuming no reliability issues with the electric breaks (hello sudden rain storm), mechanical is a cheap and weight efficient way of adding braking to the second hub.
Virtually everything besides Rolex, Patek, AP and Vacheron is in stock. For anyone on the wait-list or considering going grey market for a high demand model, I'd strongly recommend looking at comparable models from the wide variety of competing manufacturers. Not only will you get a lot more watch for your time and/or money, you'll support the breadth of artistry that makes the industry so vibrant.
One issue with solar is where we put it all. If it turns out that a meaningful portion of farmland has an excess of solar energy, that takes a big bite out of the problem. Powering the US entirely on solar might take a land mass equivalent to 2% of the country... Only a small portion of the 40% of US land area used as farmland.
This is a non issue. Rooftops alone are enough to power the US with solar, versus prime land. With that said, there is enormous potential in the roofs yet to have solar installed, parking lots with solar canopies, marginal land, floating PV systems at reservoirs, etc. Land is not an issue. At this rate, we’re constrained by pv module costs, deal flow, permitting, and install labor (a combination of labor and soft costs, essentially, with a healthy dose of supply chain issues).
Having PV above water is something we should do immediately.
As this article points out it seems to help with evaporation and evaporation is a big deal [1]
water out here and heading south just sits in concrete canals waiting to be flooded inefficiently onto crop land. but using way better irrigation is another topic.
We already devote enormous tracts of land in the US for energy from solar for transportation, way way more than we'll ever need for PV. Fully 40% of the US corn crop goes to ethanol.
People talk about how bad solar efficiency is in turning sunlight into usable energy at around 20%, corn is only able to do 1-2% and then it has to be processed into ethanol. Thus, replacing corn for ethanol with solar would result in massively more energy available for our use (not that I think that would be a good idea or that we could even use that much solar electricity).
edit: And I should add that there's likely to be plenty of farmland becoming available due to water shortages. Think about it, say you are a farmer that has water rights and use it to grow a low value crop like alfalfa. You can put up solar panels and sell your water rights and you don't have to do any work. Or if you rely on groundwater, lease your land for solar for 20 years and let the aquifer recharge during that time.
I think most of the recent progress has been in lowering prices, while the amount of power you can extract from a square meter of land presumably hasn't changed much. But I don't actually remember any serious commenter suggesting that running out of physical room was ever an actual consideration when it came to solar.
We'd have to solve some environmental problems with solar panels if we wanted to do that. Panels have been found to leak lead and cadmium into the environment. We should probably keep them away from our food until that's fixed
That paper doesn't support your claims. They didn't test for lead leaching, and they tested pulverized solar panels in strong acid. Moreover, they were cadmium telluride solar panels, which have been obsoleted by cheaper polysilicon. Polysilicon PV panels don't contain cadmium and don't contain a significant amount of lead.
That would be nearly enough to power the world; not just the US. Powering the world would take a bit over 115000 square miles, apparently. About 3% of the US landmass.
I recently retrofit a new HVAC system and as a result have also gone on a bit of a deep dive on indoor air quality. The big thing I learned is that most homes -- even old "leaky" builds -- have rather poor ventilation, meaning all sorts of compounds build up in the air... CO2, formaldehyde, VOCs, PFAS, etc. Air purifiers work for particulate, but don't really make a dent for chemicals. IIRC, You would need like a 50 gallon drum of activated carbon to do anything on the chemical front.
A quick solution is to crack the windows, or if you live in a non-temperate climate, install an energy recovery ventilating system.
Energy Recovery Ventilators or Heat Recovery Ventilators are absolutely essential (and, I think, part of code in many places!) in this era of tight and sometimes extraordinarily tight (e.g. Passivhaus) home building.
When we bought our home, the HRV wasn't working and once I replaced a bunch of parts in it, the difference in the quality of the air was noticeable just in the fact that it smelled fresh like the outdoors.
In your deep dive, you probably ran into the evergreen debate about running ERV/HRVs in the summer... I just gave up, turn it off when we run the A/C and open the windows occasionally... BUT I think you could probably run a humidistat/hygrostat hooked to the HRV (a common option in the new units, I believe).
I’m based in Tokyo and have spent the past few months going down the rabbit hole of indoor air quality. It started out of concern for the health of our four-year old - lots of time indoors on account of the pandemic, etc.
We have HEPA filters in every room now and portable CO2, PM2.5, VOC monitors, etc for keeping an eye on things. As others have stated, however, this does nothing to address the VOC issue and so I am very keen to take the additional step of installing an Energy Recovery Ventilator or Heat Recovery Ventilator, as you suggest.
If anyone here has Japan or Tokyo-specific information on manufacturers, suitable systems and/or contractors capable of doing the work, I for one would certainly be grateful to hear it!
I'm in SF. The tricky thing here is that outdoor humidity is often so high that a humidistat would only result in an 'always on' system. I think CO2 is an objectively better measure anyway. You can remove humidity and particulate with energy efficient machines. You can't (realistically) do that with CO2 / VOCs.
Did you find any industry ventilation standards related to all the compounds you listed? IIRC, ASHRAE 60.1 is the industry standard but years ago at least, it was based mainly on using "bio-effluence" as a proxy for air quality. I.e., reducing stink.
>install an energy recovery ventilating system.
These are a good idea, but the exact type is important or else you risk cross-contamination between the exhaust and intake. That's why many designs (e.g., heat recovery wheels) are generally banned in some applications like healthcare.
With the crowd that HN attracts, I'd be interested if anybody has implemented some sort of demand-control ventilation in their home.
I think an ideal heat recovery system would probably sit mid-stream in a central air system with a built in CO2 trigger. Basically, the return air gets exhausted while heating the incoming/supply air when CO2 concentration > X. Obviously you run into the capex vs ongoing energy cost tradeoff in designing the system.
Strangely, I couldn't find a ventilator on market with a CO2 sensor, but there are plenty with humidity sensors. I think CO2 sensors are on the horizon though, here's a study featuring such a system: https://core.ac.uk/download/pdf/43245317.pdf
My current system is actually ductless however, so I will probably have to rely on natural diffusion... I do have an air quality monitor which indicates that diffusion is likely sufficient (for a one floor open plan condo), but you'll optimally need to sleep with the bedroom doors open.
Edit: I haven't looked too deeply at the standards. My little sensor indicates that if you keep CO2 in range, VOCs will also also be in range, which conforms with my intuition.
CO2 sensors are common in commercial HVAC systems - especially for large auditoriums or rooms where you expect high occupancy. Economizers will automatically open to increase the exchange of outside air. My church has an auditorium that can seat up to 1500 - all four AC units have CO2 detection built into them and the concentration is displayed on the controls too.
>Basically, the return air gets exhausted while heating the incoming/supply air when CO2 concentration > X.
That’s the basic idea of demand control ventilation but how are the two air streams interfacing? If our concern is air quality, how is cross contamination between the two mitigated?
I was confused at first by a lot of diagrams I found online, but the wiki is pretty good. Basically think of a two way radiator. Hot air flows through air channel blades on the way out, cold air flows around the blades on the way in, with filtering optional at this point. Some systems indicate that they literally mix the air, which is obviously not going to be optimal, the air needs to be fully separated with the energy exchanging through a metal layer.
