Lithium batteries are the standard type of battery used in things like pacemakers. They are they dense and very safe.

Of course, not to be confused with lithium ion batteries.

> Plants are more efficient in terms of energy generated per photon absorbed.

That is an incredibly misleading, since chlorophyl does not absorb all photons. It doesn't absorb any infrared, and is mostly transparent between 500 and 600 nm. So by that measurement, you're not counting about half of all sunlight that hits a plant. Silicon based solar may be less efficient per photon, but it absorbs everything from 800nm up to UV.

> but this could be fairly easily addressed when adapting the technology for a PV cell.

You mean DSSC cells? I suppose it's "easy" to demonstrate the effect in a lab under controlled conditions, but in real world applications, where they need to work for decades exposed to the environment, it stops being easy and becomes very, very hard. There's a reason you can't buy them.

They are also not projected to be more efficient than regular solar panels under sunlight, there's just hope that they might become cheaper.

Plants are significantly less efficient than solar panels, particularly because they are limited by the amount of CO2 that they can get. 400 PPM is a lot when it comes to climate change, but when you're trying to synthesize carbohydrates, that's a problem.

On top of that, photosynthesis only works in a narrow temperature range, it requires a lot of water that just gets evaporated, and it requires minerals and nitrogen, which have to be produced expending a lot of energy.

You can actually read out the public key from Whatsapp and use that to verify the encryption scheme.

But that would be of little use if they could extract private keys or plaintext messages from the device.

Not gonna be cheap. These kinds of cells are only really useful for applications where area and / or weight are critical. Why use super complex technology with monocrystalline silicon and a novel semiconductor on top, if you can get 50-60% of the output with a bog-standard polycrystalline cell?

Producing concrete is an ecological disaster in itself, not to mention the cost. And while it won't evaporate, it'll break down as it's stacked and unstacked for thousands of cycles.

Concrete wouldn't be scalable though, because the mass that can be lifted is limited by the weight that the mechanism can move up and down. So you get a few minutes of power at most before all the weight is on the ground.

With pumped hydro, any single pump and turbine can pump water between huge reservoirs. They can potentially provide power through an entire night or more.

So gravity storage with solids is more an alternative to flywheels and batteries, which have a much different role in the grid.

Well with renewables, there's a lot of fluctuation all the time. If solar and wind are able to power the entire country on a calm and cloudy day, there's going to a lot of excess during windy sunny days. Green hydrogen generation would ideally utilize these peaks.

No. If you're on the outside of the wing, you're sitting at the long end of a lever. The barrel of a conventional airplane meanwhile is the fulcrum. So where you would barely feel the plane going into a bank if you're sitting in the barrel, even slight corrections would noticeably move passengers up and down significantly in a large flying wing.

The banking is the problem. Not so much on a small plane, but imagine sitting on the outside of a 747 wing when it banks into a turn...

Water makes up half the exhaust of conventional aircraft engines as well. Besides, unlike CO2, water precipitates.

Pesticides are an eternal cat an mouse game. The herbicides in use now will inevitably become useless as weeds develop resistance. So having a cost-effective way to kill weeds without use of chemicals will be hugely attractive, regulations or not.