"so he is touting something that really won't be a major source of energy. maybe 1 or 2%? "
That has nothing to do with your initial statement that implied the US was looking to corner the algae market.
"how much should taxpayers be on the hook this time?"
As little as is feasibly possible, like any other new technology.
"how many solyndras do we have to see go bust before we realize govt doesn't know how to pick winners in the market?"
How many more successful wind farms does there need to be before you admit that sometimes they can?