Just listened to this and he himself is not advocating “a World Without Money” whatever the organiser of the event at which he spoke might have in mind. The argument he puts forward about a society charging interest being mathematically impossible in the long run because it requires an impossible exponential growth was refuted long ago by Marx in chapter 24 of Volume III of Capital where he quotes the Rev Dr Richard Price as writing in 1774:
Money bearing compound interest increases at first slowly. But, the rate of increase being continually accelerated, it becomes in some time so rapid, as to mock all the powers of the imagination. One penny, put out at our Saviour’s birth to 5 per cent compound interest, would, before this time, have increased to a greater sum, than would be contained in a hundred and fifty millions of earths, all solid gold.
But Price entirely forgets that the interest of 5% presupposes a rate of profit of 15%, and assumes it to continue with the accumulation of capital. He has nothing whatsoever to do with the actual process of accumulation, but rather only with lending money and getting it back with compound interest. How that is accomplished is immaterial to him, since it is the innate property of interest-bearing capital.
Professor Hörmann makes the same mistake. The capitalist economy does not expand because banks lend at compound interest but because workers produce surplus value. As interest has to be paid out of surplus value it cannot be greater than this and in fact is a great deal smaller. It is profit not interest that drives the capitalist economy.