Subject: Re: [bitcoin-dev] Libre/Open blockchain / cryptographic ASICs

From: ZmnSCPxj <[email-masked]>
Date: Wed, 03 Feb 2021 03:17:48 +0000

Good morning again Luke,

> [my personal favourite is a focus on power-efficiency: battery-operated hand-held devices at or below 3.5 watts (thus not requiring thermal pipes or fans - which tend to break). i have to admit i am a little alarmed at the world-wide energy consumption of bitcoin: personally i would very much prefer to be involved in eco-conscious blockchain and crypto-currency products].

If you mean miner power usage, then power efficiency will not reduce energy consumption.

Suppose you are a miner.
Suppose you have access to 1 watt of energy at a particular fixed cost of 1 BTC per watt, and you have a current hardware that gives 1 Exahash for 1 watt of energy usage.
Suppose this 1 Exahash earns 2 BTC (and that is why you mine, you earn 1 BTC).

Now suppose there is a new technology where a hardware can give 1 Exohash for only 0.5 watt of energy usage.
Your choices are:

* Buy only one unit, get 1 Exohash for 0.5 watt, thus getting 2.0 BTC while only paying 0.5 BTC in electricity fees for a net of 1.5 BTC.
* Buy two units, get 2 Exohash for 1.0 watt, thus getting 4.0 BTC while only paying 1.0 BTC in electricity fees for a net of 3.0 BTC.

What do you think your better choice is?

That assumes that difficulty adjustments do not occur.
If difficulty adjustments are put into consideration, then if everyone *else* does the second choice, global mining hashrate doubles and the difficulty adjustment matches, and if you took the first choice, you would end up earning far less than 2.0 BTC after the difficulty adjustment.

Thus, any rational miner will just pack more miners in the same number of watts rather than reduce their watt consumption.
There may be physical limits involved (only so many miners you can put in an amount of space, or whatever other limits) but absent those, a rational miner will not reduce their energy expenditure with higher-efficiency units, they will buy more units.

Thus, increasing power efficiency for mining does not reduce the amount of actual energy that will be consumed by Bitcoin mining.

If you are not referring to mining energy, then I think a computer running BitTorrent software 24/7 would consume about the same amount of energy as a fullnode running Bitcoin software 24/7, and I do not think the energy consumed thus is actually particularly high relative to a lot of other things.

Regards,
ZmnSCPxj