Maybe someone has a really clever idea but I do not think anything rooted in the real world can work. You will always need some kind of sensor to record whatever it is that you are doing in the real world and you will have to prevent people from faking those sensor readings. If you had a central authority as root of trust you might be able to build some tamper-proof device that provides cryptographically attested values but I can not think of a way to do something like this without already having a root of trust.

This is called the oracle problem.

The proposed solutions are in the same vein as security in base layer consensus mechanism: create an economic incentive to be accurate over time. Make sensors/sensor data compete to be designated as roots and gain some sort of revenue. Reputation is hard to build, but easy to destroy.

I think they are similar but not identical problems. For things like some stock price I can see how you could have several competing oracles that can build trust over time, but if you want to monitor and report the amount of solar energy I am producing for mining I can not see how this could work. Especially not if you want to preserve anonymity which kind of rules out that miners crosscheck each other by placing their own sensors.

Kevin O'Leary from Shark Tank pushes for a sustainable Bitcoin. His proposed solution is to have basically "certified" Miners mine clean Coins and never exchange them. Of course if this takes over Bitcoin isn't really decentralized anymore, but he thinks Institutional Investors would prefer that.

If you are willing to do that, then make them certified ledger maintainers and throw out the entire mining overhead and make them use a good old SQL database. Sprinkle as much cryptography on top of that as you want to feel happy about unforgeability and such. The only reason to have a mining process is to allow anonymity, when you give up on that, mining becomes pointless. Also Bitcoin has not been decentralized for a long time, the idea that every Bitcoin user gets a vote in the consensus process went out the window a decade ago.

I'd say the most effective way for me to scrub a lot of CO2 out of the air is to burn a lot of fossil fuels, and then scrub 80-90% of it (or however efficient scrubbers are). Seems like the wrong incentive?

I feel this is somewhat similar to the story with trees. See e.g. https://www.bloomberg.com/news/newsletters/2021-04-21/money-... and https://www.theguardian.com/environment/2021/apr/11/negotiat... .

Well human labor is a somewhat renewable source of energy. And when people perform work for us it saves us the energy of performing the same work ourselves in the future. And when people perform work to produce artifacts such as planted crops, structures, machines, buildings, materials, working inventory the work is stored in physically observable material capital held on land. If we want to coin the material capital and place a shared currency into circulation backed by material capital this can be accomplished by having public employees of local land loan offices appraise the minimum labor replacement cost of the material capital which the borrow agrees to hold on site and require the loan to be repaid before the capital fully depreciates.

If you don't mind a completely centralised cryptocurrency, https://solarcoin.org distributes coins based on how much solar energy you produce.

That's great, but doesn't really compete with Bitcoin and others, which aim for censorship-resistance through decentralisation.

That is basically what Bitcoin is... because the cheapest energy is the one you can produce yourself from renewables.

Using resources to build a solar panel that only generates electricity to feed into a bitcoin mine that basically turns that solar energy straight back into heat is a net energy negative. The only conceivable benefit is increased economies of scale for the production of solar panels.

I am talking about generating electricity and NOT using it for mining.

You're only thinking of honest miners.

The cheapest energy is the one you steal.

If this were true, we would not be in the middle of a climate crisis right now.