I am really intrigued by using sand for energy storage - what I don't get (not my field) is given a typical 2000sf house, located in the colder part of the country as an example, how much heat could be stored for how long? i.e. is it even feasible to use solar panels to power resistance heaters all spring/summer/fall, to save up enough heat to keep a house warm for the entire winter? if so, how many panels would you need and how big a sand battery would it take.
I am not planning on doing this, but explaining it on a scale that I can relate to would be helpful, because I know, for example, that said house can store a winter's worth of heat in a 1000 gallon oil tank, or small woodshed big enough for 6 cords of wood.
> In Alberta, Canada, the homes of the Drake Landing Solar Community (in operation since 2007), get 97% of their year-round heat from a district heat system that is supplied by solar heat from solar-thermal panels on garage roofs. This feat – a world record – is enabled by interseasonal heat storage in a large mass of native rock that is under a central park. The thermal exchange occurs via a cluster of 144 boreholes, drilled 37 metres (121 ft) into the earth. Each borehole is 155 mm (6.1 in) in diameter and contains a simple heat exchanger made of small diameter plastic pipe, through which water is circulated. No heat pumps are involved.
That development is 52 homes. They are presumably engineered to be highly energy efficient and it's not a perfect comparison to sand, but it's less than I'd have imagined.
A very low key variation of heat storage is using a ground-source heat pump in winter and then in the summer using the same heat pump for cooling the house and replenishing the ground source while doing so.
Small ground sources, or ground sources with neighbors too close who do the same, will actually accumulate noticeable ground cooldown from season to season if they are not replenished. Free air conditioning comfort from the replenishing effort, or free replenishing from the air conditioning, you can spin it however you like. It's very low gradient and certainly won't get you through winter without a another power source, but it absolutely is seasonal heat storage.
I don't think that the sand units you can install in your home have the ability to store energy across seasons. They are more like hot water heaters; heat when you have solar, but you can use some hot water at night when electricity is more expensive.
So this would be like, in a mild climate, the sun is going to keep your house warm during the day and you are generating some solar. You use the solar to heat up the sand, and then overnight, you recover some of that energy to use for heat. (I think you can get electricity back out of the heated sand as well, but it's like 70% efficient compared to >90% for a lithium battery. So I think the big application is in heating, less for charging your car after you get home from work.)
A single house is too small to make that work. I can't see how you could insulate such a small volume for more than a few hours. It can start to work at district scale, but the Finns are just targeting a few days.
I think this is a surface area/volume problem. A smaller installation is going to have a larger relative surface area given the amount of stored heat, so your losses/insulation requirements are going to be much worse.
The temperatures we’re talking about (1000C) would be incredibly dangerous in residential applications, plus a small installation would lose too much energy to the environment due to the ratio of surface area to volume. More practical IMO is to use a daily cycle like what Harvest Thermal is doing: store energy in your water heater tank during the daytime and release it at night.
A 1000 gallon tank stores about 146 gigajoules of energy (diesel motor fuel = 138,700 BTU/gallon, "138700 BTU * 1000 in gigajoules").
1000 gallons of sand (about 6000 kg) heated 1000 °C above ambient stores about 1000 K * 6000 kg * 1.1 kJ/kg-K (from the paper, on page 9) = 6.6 gigajoules.
So to match a fuel tank for energy storage, it needs to be at least 22x the volume, have extremely good insulation (even more volume), a heat-exchanger, and sand-handling augers. Additionally, the sand needed to be heated in the first place, which means a good electrical connection, but if you have that power in the first place, just use that during the winter? The nice part about fuel is that a man and a truck can move a few thousand gallons of hydrocarbons several hundred miles out to the middle of nowhere and transfer that energy at megawatt speed with a hose.
Huge amount of the rural population already have an oil or propane tank sitting within a hundred yards of their house. Being even slightly remote means you require backup heating options for when things fail.
States have a similar setup patterned off the federal government, with most things falling only in the purview of the states. In this case they're correctly making sure that vaccines delivered as food are correctly treated as such under the framework here https://unicourt.github.io/cic-code-tn/transforms/tn/octn/r7...
Considering the active development this is very forward thinking and timely
Again, under Federal law and regulation, these theoretical products are likely to already be deemed drugs (and this determination would almost certainly preempt any state decision in the opposite direction). The legislation is, at best, redundant.
I am someone who has 'done my own thing' for more than 35 years at this point - i.e. direct contracting with my own clients, occasionally working on some 'side' project I hope I could sell, and even took a FT position here and there when the right opportunity came along.
My feeling is it has not hurt my career at all, and more likely made it better - having your own company, with your own clients and working on lots of things you learn lots of skills you likely won't learn grinding it out for mega-corp year after year.
Other big bonus is, on my resume - there are no gaps - I was either on someone else's payroll (for me less than 5 years of my 35 years of work) or doing my own thing - I never had a recruiter or hiring manager question 'gaps' - on paper I was 100% employed at all times, which is easy to say if you have your own little corp - even if you were technically idle at times.
IMO if you have some money to get thru thru for a while (i.e. you won't be homeless if you don't get a check every two weeks), this is the perfect economy for doing your own thing.
tariffs and or new taxes on the chips imported from other countries would have served that same purpose - without the need for more billions of corporate welfare.
I disagree - if 'everything can be a process' we wouldn't need human judgement anywhere - and clearly we clearly still do need humans in the loop - and the reality is the judgement of humans is not all created equal. Some are better than others.
Blame-oriented cultures result in people hiding problems, which makes them worse in the long run.
That doesn’t mean people aren’t accountable for their actions in “blameless” cultures, but problems are first assumed to be the result of systemic issues, deserving to be fixed, rather than individual issues, deserving to be punished.
The first one would refresh all the cached information after a marketing database update. The second would stop all the webservers.
Guy's first day; I'm showing him the ropes; we push the marketing data update and set about regenerating all the cache files by manually picking the correct file from the folder of all possible files. I'm sure we can all guess what happened to make this a story remotely worth telling...
Complete site outage. Completely unnecessary. Completely human error.
Should we blame the guy who clicked on the file that was directly adjacent to the one he intended? Should we blame me as the guy overseeing the training? Or should we change the system so that files that we use multiple times everyday and are safe/innocuous are't right next to an E-stop/EPO button? Or maybe we should change the system so that pushing marketing data refreshes the caches files automatically?
Blameless culture favors the latter actions over the former and tends to make your operation stronger and more resilient over time. The experts (and the novices) who made the mistake can speak freely about what happened and how we might prevent it, without fearing reprisal.
If someone repeatedly kills the site by mistake time after time, despite reasonable safeguards being in place, they should face disciplinary action. But when they make an honest mistake because we left an idling chainsaw laying around on the workbench, it makes no sense to blame them for grabbing it by mistake.
You are conflating criminal acts with engineering problems.
As stated earlier, blameless postmortems are for RCA of a particular incident. If you shoot every engineer who causes a incident you will succeed in having no incidents because no one will bring them up or making any changes for fear of getting shot.
You might want to, but whether you should do it is a separate question of its own.
If you promise people that there will be no blame, no punishment, no nothing, then they may speak more forthrightly. Do you want that honesty or do you prefer to retain the option of punishment?
because in the end the powers at work will make sure that the blame goes to some person turning a wrench instead of finding the real reason and the real source of the blame, most likely a process or inadequacy of redundancy/checks-and-balances would have been the real fix. Pointing at Max over in Wrenching because he left a wrench in the motor because he's been working double shifts for months on end does not fix future issues, and Hank the Replacement will likely make a similar mistake at some point in the future
Same here, never understood the march towards 'blameless' culture - if someone is to blame, they should be blamed; if there is a pattern of mistakes they should be shown the door as quickly as possible.
Because if there is someone who is at fault, their reaction will be to throw someone else under the bus. So you may end up with a situation where the person being blamed isn't actually the person responsible for the accident.
I have worked in companies where the focus was finding who is responsible for failures. The result was that minor incidents were covered up to save bonuses and the problems (in the Problem Management context) that led to them were invisible to the management. When problems are invisible there is a tendency to push into safety margins to cut costs (known as normalisation of deviance) which ultimately leads to uncontrolled incidents.
In my current role I promote a blameless culture and the result is my team proactively raise incidents. We have more incidents than other teams but the incidents are generally controlled and problems are visible, prioritised and closed off. Coincidentally, my teams have record high Mean Times Between Failures and I'm now working with the other teams to fix their safety culture.
The lack of thinking about safety culture in this way is one of the reason that I don't believe most "Software Engineers" should be considered engineers.
I am not planning on doing this, but explaining it on a scale that I can relate to would be helpful, because I know, for example, that said house can store a winter's worth of heat in a 1000 gallon oil tank, or small woodshed big enough for 6 cords of wood.