What's the round trip efficiency of something like this, and what's the rate of loss to the environment? There's been a couple of these posted in the last few days and I have no feel for these numbers.
Data from Drake's Landing in Aberta has a COP of 30 (30kw of heat per kw of electricity)? The heat stored is waste heat - otherwise lost to the atmosphere, so storing it until use is should be compared to typical heat pump COP of 2-4.
The concept seems to be similar to the "Gridscale Storage"[0] system sold by Stiesdal technologies[0], which claims a round-trip efficiency of 55-60%.
The important insight here is that per Carnot's law[1], the higher the storage temperature the higher the theoretical max efficiency for thermal storage. Stiesdal had an initial concept that stored at even higher temperatures (1000C) and used a standard power plant steam turbine for converting back to electricity. But these turn-key solutions are probably more realistic.
If you are interested in realistic renewable energy, do browse the Stiesdal pages: Henrik Stiesdal [2] was pretty much the inventor of the modern wind turbine (sold the upwind 3-blade design to Vestas, CTO at Siemens Wind Power): He seems to have a superb intuition for industrializing heavy machinery. I am keenly following his advances into electrolysis and floating offshore wind power.
This was the question I came to pose... This is such an exciting field but when the CORE most important variable is missing, I tend to assume the worst - in this case being that the value is atrociously low.
The RTE of turning electricity into heat (or hot water into hot sand into hot water) is pretty good, most of your problem will be environmental losses between the heating station and the end-users.
It's not going to be as good as a heat pump, but they don't work very well in very cold climates, and storing electricity (or energy that you turn back into electricity) is expensive/lossy/difficult.
This is an article by ourworldindata, who aggregate a bunch of (mostly economic) metrics from countries around the world. It is common for energy use to be reported in that way on a country level. This looks like an explainer for the users of their website on what the terminology means.
It makes perfect sense when you think about who the audience for this data is, economists, planners etc. In those roles, the primary concern is the actual quantity of heat and electricity that the population needs in their homes and workplaces, and you need to be able to back that out to how much raw fuel that requires, or how much transmission capacity you need. You need to know this summary info so you know where the focus needs to be. At moment for instance, they need to know how much gas they need in storage tanks in Europe for this winter, and it's information like this that helps them figure that out.
I suppose having non-technical terms makes sense considering the audience, but I would still want the fine print (i.e. this article) to explain how the non-technical terms map to technical concepts.
At the least, I would prefer renaming the non-technical terms to be less abstract:
So you're saying the most efficient capital allocators are getting more capital to allocate. Huh. If only we could build a system around that idea... ;)
This looks extremely cool. I'm doing a masters right now and would definitely use it!
My one question though would be how are the notes stored? Is it possible to download them as latex or a markdown file or something? If I have to keep up a membership to return to them that would be unfortunate.
Cool project though, there's definitely a need for something more fluidly interactive in the university notetaking space. Best of luck!
Thanks a lot! No there'll definitely be export options. As of now there's only a beta version of exporting as a PDF, but LaTeX/Markdown is on the cards. Probably LaTeX so that we can just replace the PDF generation as well.
Layoffs seem to be up, but that's a questionable chart if ever I saw one. I doubt they have had representative coverage of the market for that whole period. With those numbers, looks like it's as much a chart of the increase in their data collection on layoffs as it is a chart on layoffs.
