1. Has anyone considered that it might be technically not possible to completely 'power down' mining rigs during this 'cool-down' period of time? While modern CPUs have power-saving modes, I am not sure about ASICs used for mining.

2. I am not a huge data-center specialist, but it was my understanding that they charge per unit of installed (maximum) electricity consumption. It would mean that if the miner needs X kilowatts-hour within that 1 minute when they are allowed to mine, he/she will have to pay for the same X for the remaining 9 minutes - and as such would have no economic incentive not to draw that power when idling.

3. Not really a criticism of the idea to reduce Bitcoin energy consumption, but rather a couple of observations:

(a) Environmental concerns cause Bitcoin to be less popular and thus push the price lower, which in turn lowers miner's power consumption (lower Bitcoin price => less they can afford to spend on electricity). So it is a self-stabilizing system to begin with.

(b) Crazy power consumption may be a temporary problem, after the number of halving events economic attractiveness of mining will decrease and power consumption with it.

4. My counter-proposal to the community to address energy consumption problems would be to encourage users to allow only 'green miners' process their transaction. In particular:

(a) According to this source (https://www.blockchain.com/charts/transaction-fees-usd), fees represent approximately 12.5% of total miner reward. Not a lot, but not insignificant either.

(b) Based on the method used in this source (https://digiconomist.net/bitcoin-energy-consumption/) to offset CO2 emissions of bitcoin mining the miner would need to spend approx ~3.6% - 7.2% (depending how 'dirty' is his power source) x 87.5% (mined portion of its rewards) of its fees (assuming 50k Bitcoin price and 15$ / tonne of CO2 price of carbon offset).

(b) Should there be some non-profit organization(s) certifying green miners and giving them cryptographic certificates of conformity (either usage of green energy or purchase of offsets), users could encrypt their transactions and submit to mempool in such a format that only green miners would be able to decrypt and process them.

Users routing transactions specifically to 'green miners' (and posting potentially higher fees) would create economic incentives for miners to use green energy and/or buy CO2 offsets, as described above with ~3.1% - 6.8% of total revenue cost to offset CO2 vs.12.5% of fees component in mining, if majority of users would use the routing to green miners method - there is a chance that Bitcoin network will become significantly greener.

Anton.

On Sun, May 16, 2021 at 8:02 PM Karl via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:

[sorry if I haven't replied to the other thread on this, I get swamped
by email and don't catch them all]

This solution is workable but it seems somewhat difficult to me at this time.

The clock might be implementable on a peer network level by requiring
inclusion of a transaction that was broadcast after a 9 minute delay.

Usually a 50% hashrate attack is needed to reverse a transaction in
bitcoin. With this change, this naively appears to become a 5%
hashrate attack, unless a second source of truth around time and order
is added, to verify proposed histories with.

A 5% hashrate attack is much harder here, because the users of mining
pools would be mining only 10% of the time, so compromising mining
pools would not be as useful.

Historically, hashrate has increased exponentially. This means that
the difficulty of performing an attack, whether it is 5% or 50%, is
still culturally infeasible because it is a multiplicative, rather
than an exponential, change.

If this approach were to be implemented, it could be important to
consider how many block confirmations people wait for to trust their
transaction is on the chain. A lone powerful miner could
intentionally fork the chain more easily by a factor of 10. They
would need to have hashrate that competes with a major pool to do so.

> How would you prevent miners to already compute the simpler difficulty problem directly after the block was found and publish their solution directly after minute 9? We would always have many people with a finished / competing solution.

Such a chain would have to wait a longer time to add further blocks
and would permanently be shorter.

> Your proposal won’t save any energy because it does nothing to decrease the budget available to mine a block (being the block reward).

You are assuming this budget is directly related to energy
expenditure, but if energy is only expended for 10% of the same
duration, this money must now be spent on hardware. The supply of
bitcoin hardware is limited.

In the long term, it won't be, so a 10% decrease is a stop-gap
measure. Additionally, in the long term, we will have quantum
computers and AI-designed cryptography algorithms, so things will be
different in a lot of other ways too.
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