Updated: Jul 25, 2019
As great as it was for introducing the world to the idea of decentralized currency, Proof-of-Work is an extremely energy inefficient algorithm. Let's face it, Proof-of-Work is specifically designed to measure how much "Work" miners have done, where 90% to 95% of the cost of mining is electricity (source).
This work simply involves picking and hashing random numbers. In order to reduce or eliminate transaction fees while maintaining security as well as fighting CO2 pollution, the cryptocurrency movement must find a more energy efficient alternative.
This blog post is dedicated to calculating the difference in energy usage between Proof-of-Work and Proof-of-Person. Whether using Proof-of-Person, or Proof-of-Work for our calculations we assume every user is running a mobile wallet on their phone. On top of this, every system has its own mining system which uses further energy.
How much energy does Frink use per user?
Frink mining is so optimized that it barely requires more energy than required by an SPV wallet which must verify the block headers. We tested the energy usage of a SPV Bitcoin wallet for Android. For our testing we used the wallet recommended by bitcoin.org simply called “Bitcoin Wallet”. We also used AccuBattery to measure the energy usage of the application running on the mobile phone. We found that this APV wallet uses an average of about 600mA to run. Assuming a 4V battery, this means it takes 2.4 W per user to run the wallet. This makes it fair to estimate that POW, and POP all use roughly 2.4 W to run a wallet.
We can estimate that 99% of the time the average Frink miner only needs to expend as much energy as an SPV wallet to keep up to date with the network. But let’s be fair and add on the extra energy due to everyone mining. With Frink at any point in time only 1% of the network needs to be monitoring all transactions as Frink miners will know in advance when it is their turn to mine. Only during this time do they need to be checking transactions to validate the fork they intend to mine off of.
Let’s estimate the average number of transactions per second Frink has to support. Frink subdivides the network into connected communities each having a size of 1 million members at the high end. Bitcoin currently has roughly 30 million users and is maintaining roughly 3 transactions per second. This means that 18 times less users, who would make 1 transaction every 6 seconds on average.
Assume we have 10 second blocks meaning roughly 2 transactions per block and this means that the size of a block is roughly equivalent to the size of a transaction.
Also assume that the amount of energy used while mining is roughly linear with the number of transactions being processed. This means that users are using roughly 3 times more energy 1% of the time. Or in other words Frink uses roughly 3% more energy to mine than to run the smartphone wallets. This estimate means that Proof-of-Person uses roughly 2.5W for the users wallets and phones.
How much energy does Proof-of-Work use per user?
The Bitcoin network miners are currently using an estimated annual 73 TWh to support the previously mentioned 30 million users according to Digiconomist.net This works out to 2.43 TWh per year per user used by Proof-of-Work currencies.
How much more efficient is Proof-of-Person?
Now, let’s determine the estimated amount of energy used per year per user for Proof-of-Person. Considering a year has 8760 hours in it, 2.5W * 8760 hours/year = 21.9 kWh/year per user.
2.43 TWh/ 21.9 kWh = 111,000,000
In other words, if Bitcoin were to use Proof-of-Person rather than Proof-of-Work it would currently be consuming roughly 110 million times less energy!