increasing supply curve and non-binding constraint: scarcity rent=0, producer surplus is positive

constant supply curve and binding constraint: scarcity rent = producer surplus

Definition:

scarcity rent is the forgone oppotunity cost of the resource for future generation.

producer surplus is the totoal difference between the price and willingness to pay (WTP)

生产者剩余与经济租都是供给一方所实际取得的收入高于其要求的收入，在这一点上是等同的。但是经济租是相对于要素供给者而言的，而生产者剩余是相对于厂商而言的。