In BTC land PoW = fee. In RaiBlocks they use it more like a Captcha before sending a transaction, effectively getting rid of Fees because it's just as useful a

In BTC land PoW = fee. In RaiBlocks they use it more like a Captcha before sending a transaction, effectively getting rid of Fees because it's just as useful anti-spam. (However, I think that fee transactions are actually quite important in a blockchain because you don't want nodes wasting resource adding and checking nonsense even if the captcha was computed.)