energ8

"significant increase in the range of 10.7-42.2% for lightweight and aerodynamic efficient vehicles" shout out to aptera motors https://aptera.us/vehicle/ that's currently vapor ware "Designed with ~700 watts of integrated solar cells, drive up to 40 miles per day completely off the grid and enjoy 400 miles of range per full charge"

It's a thing in from thousands of years ago https://en.m.wikipedia.org/wiki/Yakhch%C4%81l and today https://en.m.wikipedia.org/wiki/Passive_daytime_radiative_co...

for PDRC there are a couple good videos about it from NightHawkInLight https://youtu.be/N3bJnKmeNJY?t=19s, https://youtu.be/KDRnEm-B3AI and Tech Ingredients https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=dNs_kNilSjk

I have seen repeated claims of heat pump CoPs improving over decades. Can anyone summarize or provide links to what improvements are being made? Compressor technology? refrigerants? Fans to move heat? all of the above? Where is the path from here?

There might be an additional benefit for fossil fuel trains. Point source capture is usually more efficient than direct air capture.

This isn't necessarily directly point source, but if the diesel exhaust is partially directed into the capture train, the CO2 concentration should be higher, and could have a more efficient CO2 capture.

It'd be somewhat custom, but there is a commercial heat exchanger (https://www.hotspotenergy.com/pool-heater/) that an HVAC tech should be able to install

You might be interested in this paywalled paper (or similar ones): https://pubs.acs.org/doi/10.1021/acs.iecr.0c02255

> by applying heat

More heat than is common for home appliances I know! A commonly referenced stat is 825 C. There's really a gradient: https://en.m.wikipedia.org/wiki/Calcium_carbonate#Calcinatio...

From my armchair-research, there are scale challenges with plants.

Algae is commonly the go-to for CO2 scrubbing for it's relative efficiencies. Algae might scrub 1-3 grams of CO2 per liter per day (https://www.osti.gov/servlets/purl/1485133).

Humans exhale approximately 1kg CO2 per day.

I consider 300-1000 L of algae scrubber tanks per person a lot of volume.

I think there are large room diy heat pumps. "diy mini split heat" found me this [0] for example.

Also, depending on your hackerness, you could adapt window air conditioners.

From what I've seen, solar PV for heat only really makes sense if you're using a heat pump. But solar thermal for heat can be good, though. http://builditsolar.com has a number of DIY heating projects for X,000 USD in materials.

[0]: https://hvacdirect.com/perfect-aire-12-000-btu-22-seer-quick...

Residential Flywheel Energy Storage by Velkess: http://velkess.com/letter.html

Maybe sad more than surprised

Scarves are also a mainstream style choice for keeping necks warm, inside and out. Dropping the style, Neck Gaiters, Buffs, and Balaclavas are my go-tos for real cold.

The kickstarter project has transformed into Sefton Motors, which says it has engines backordered (but in production): https://seftonmotors.com/collections/all

The fans like this I've seen are powered by TEGs, just like the article is talking about. So, yes, but there is a trade-off. For those familiar with ICE engines, I'd compare it to the trade-off of a turbo/super charger.

From my reading of heat pumps, mismatches in energy sources and sinks can make linking things together more complicated (aka more expensive) than is commonly available.

For the pool <-> A/C case, This Old House did a segment on linking the systems: https://www.youtube.com/watch?v=J7fB8ul9dZw

Edit: chris_va has more details about why linking systems is hard: https://news.ycombinator.com/item?id=23001888

Yeah, FT looked insane, which is one of the reasons the linked paper was so attractive. Ethanol from CO2, electricity, and water at ambient temperature and pressure.

I mostly think I have to be doing some chemistry/math wrong, based on how not terrible the energy efficiency is. I'd love corrections or reading material, as this is not a knowledgeable area for me. - 2 CO2 + 9 H20 + 12e- -> C2H5OH + 12 OH- = 0.084 V - over voltage of 1.2 V is best - 1kWh @ 1.2V yields 30 moles electrons - 30 moles electrons has theoretical yield 2.5 moles ethanol = 0.146 L ethanol - reduced to appx 116ml ethanol due to selectivity - 116ml ethanol has raw energy of 778 Wh, probably 550 Wh recoverable with Combined Heat and Power

I think 55% round trip efficiency for energy-dense long term storage would be big. Of course, this isn't that (math is partially based on theoretical bests, ethanol isn't long term, CO2 capture and material movement not accounted for).

Thanks for the plasma reforming tip!

A previous comment on HN went something along the lines of "what is going to happen in the summer when we've built solar/wind/etc to fulfill this winter months needs?"

I started researching energy storage. Creating liquid fuels from electricity would be handy for storage. There are processes, but getting CO2 and H2 to create hydrocarbons is currently very energy intensive. On the CO2 side, I think biogas can help this out. biogas is 25-50% CO2. In biogas upgrading, CO2 is considered a waste product (with purer methane the desired output). CO2 from this source looks noticeably less energy intensive than direct air capture.

I know biogas can be done on the small scale (e.g. homebiogas.com). My research focused especially on liquid fuel creation that could work in someone's backyard. I haven't found it. "High‐Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N‐Doped Graphene Electrode" [0] was an exciting find, dampened after reading how well ethanol stores.

I mostly became convinced that existing oil, gas, and chemical companies will maintain dominance producing many of the same outputs, from a different (renewable) set of inputs.

[0]: https://onlinelibrary.wiley.com/doi/full/10.1002/slct.201601...