Gas price defines how much one unit of computation costs in an EVM compatible network like Ethereum Mainnet or POA Core. Gas price is denominated in fractions of the native token, known as Wei. For example, a simple transaction consumes 21,000 units of gas. It equals one GWei (1,000,000,000 Wei) per a unit of gas. One GWei is 1/1,000,000,000 of one POA coin. Thus, a simple transaction consumes 21,000 GWei.
How many transaction users can put into a block? It depends on types of transactions and the amount of gas they consume. Per any given block all transactions have the same gas limit per block. At POA Network the gas limit is set almost as in Ethereum and equals to 8,000,000 gas per block. To fill a block a user needs to spend 8 MM GWei. On Jul 15, 2018, the price of one POA is equal to $0.165446. Multiplying it by 8MM GWei or 0.008 POA we will get the price of $0.001323568 per a block of computation.
While the cost of computations is meager, the POA Core Network can be abused by DoS (Denial of Service) attacker. The attacker can flood the network with fluffy transactions and consume all blocks with them. You could see that type of attack on Feb 5 to Feb 18, 2018, on Core Network where a script filled blocks with transactions without purpose but to fill blocks. https://explorer.web3scan.net/n/poa/analysis/chart/txCumulativeByDay
At the moment, the gas price is set on nodes of validators. There is a social agreement between validators to keep the gas price at 1 GWei. Although, there are no technical limits to stop them from modifying the gas price.
We expect to see a form of voting by validators to increase the gas price on nodes to adjust it with the cryptoeconomy of the network.
In the next part, we will discuss a technique to peg the gas price to US dollars.