Nice one David

Biomasses concentrated release of pollutants to be counted as neutral is problematic.
The timber used is exotic with a faster life cycle than indigenous timber so an acceleration in growth is an acceleration in green house gas production as well.
Better sure but neutral?

Michael:

If you're pointing out that biofuels currently use fossil fuels in the planting, tending, and harvesting processes then I agree.

What I said was:

... from this perspective, biofuels can be said to be carbon neutral, because it's theoretically possible to manufacture and use them without adding to the overall amount of carbon dioxide in the atmosphere.

The key word here is "theoretically". The point I was trying to make is that it's possible to grow biofuels without adding to atmospheric carbon dioxide levels (i.e. without use of fossil fuels), so long as the crops are continually replanted. In fact, it's even theoretically possible to use the crop biofuels themselves for all the processing energy inputs. This is not done at the moment, but there is no scientific obstacle to it (in theory).

In contrast, of course, fossil fuels burnt in the ordinary way will always add carbon dioxide to the atmosphere, i.e. they will always be carbon positive (unless, of course, you remove the carbon dioxide post-combustion, and sequester it forever somewhere).