Is there any intrinsic scalability advantage to using proof of stake over proof of work?
Ignoring the environmental impact issue, and ignoring sidechains, can proof of stake achieve higher TPS rates than proof of work? (Presume identical block size and hardware)
No, the concerns limiting the number of transactions are orthogonal to the method of achieving consensus.
Blockspace is limited to prevent the cost of operating a node from ballooning to enable users to perform full validation. Neither the effort for PoS nor PoW scale with the number of transactions in any way.
It's a complex question because you can never just consider scalability on its own. Something to keep in mind when talking about scalability is Vitalik's infamous scalability trilema.
The trilema involves Scalability, decentralization, and security. It states that increasing one always sacrifices something in regards to one or two of the other components.
You characterize scalability as TPS. Sure it is possible to increase TPS. But to do so you have to sacrifice either
decentralization: for example, blockchains which increase block size, making nodes more resource intensive and decreasing the amount of full nodes in the network. ie BSV, BCH. This also goes for all kinds of Proof of Stake altcoins which have computationally intensive nodes to gain TPS, or which use dPOS consensus.
security: the network can resist a large amount of participants trying to attack it. 51% is usually taken as a secure amount (as for BTC or ETH), if this amount is low, ie 10%, you will usually be a permissioned network where people who run nodes are screened with KYC. A lot of high TPS alt networks hide the fact that they are actually permissioned for full nodes.
With that out of the way, does PoS intrinsically increase scalability? No, but the proponents of PoS say that it is the best way to enable SHARDING.
Sharding does claim to increase scalability without trade-off because for sharding, you get multiple connected chains and yet each node only has to process one shard chain (decided by some random selection process), therefore decentralisation is maintained while TPS of the whole goes up.
There are two problems with this narrative.
PoS is not necessarily a requirement for sharding. For example Kadena is a blockchain that does sharding with PoW.
There is a more important, insidious factor that stops scalability: state bloat. As the state of the chain increases, processing state updates becomes more and more complex. More memory is needed to store the full chain, and better processors are needed to validate state updates against the ever-growing history of the chain.
In fact the second problem, state bloat, is the reason why BTC may turn out to be wise to keep block size to only 1MB and TPS slow. Complexity of the Ethereum chain is rapidly increasing, much faster than BTC. It seems that because of state bloat, decentralisation+scalability may be doomed in the long run on ANY chain. Even with pruning it is inescapable that chain history and complexity will grow much more rapidly than computation abilities if TPS is too high.
Certain chains are focusing specifically on solving this problem, such as Nervos, which relies on a rented L1 chain to keep state small, and uses sidechains to address scalability rather than sharding or anything like that. Nervos L1 is proof of work chain.
So in conclusion, some people may claim staking increases scalability because of sharding, but this is a doubtful argument. The only thing it really does is reduce electricity costs, if it succeeds.
Is there any intrinsic scalability advantage to using proof of stake over proof of work?
Short answer: No
Long answer:
Can proof of stake achieve higher TPS rates than proof of work? (Presume identical block size and hardware)
Proof of stake is a different consensus mechanism which is based on holdings of native token. It changes lot of things but transactions per second should not be affected (tps is misleading when comparing cryptocurrencies though). Users still need to run a fully validating node, only miners are replaced with validators holding native tokens and participate in staking.
Since you mentioned blocksize and few other chains are mentioned in answer by divinesleeper, I tried to compare blocksize of Bitcoin and Ethereum:
Bitcoin: 4,000,000 weight units (WU) What's the blocksize limit after segwit and how do legacy nodes deal with segwit transactions?
Ethereum: 30,000,000 gas units https://etherscan.io/chart/gaslimit
We need to measure both in same unit (MB per 10 minutes) so that its easier to compare:
| Bitcoin | Ethereum |
|---|---|
| 4 MB | 500 MB |
500 MB is based on https://ethereum.stackexchange.com/questions/1106/is-there-a-limit-for-transaction-size/
So we don't have similar blocksize hence scaling and decentralization differs. Bitcoin developers have agreed on scaling in layers. This approach is considered better even by few altcoin developers. Decentralization involves lot of things. Most of the altcoins have premines, less people care to run nodes, supply is changed regularly etc. so even if they use proof of work it doesn't really matter.
Proof of stake helps people with lot of holdings so marketing is done to promote the advantages of a consensus mechanism that reduces decentralization. Moving from PoW to PoS on base layer is not an upgrade for any decentralized network.
Ignoring the environmental impact issue
There is no environmental impact associated with Proof of Work:
Comparison with other industries: https://bitcoinmagazine.com/business/bitcoin-energy-use-compare-industry
