UK biomass is estimated to have a total-lifecycle carbon footprint of 230g CO2 per kWh. This is much worse than wind, solar, or nuclear. But still a very significant improvement on burning coal and natural gas! Compared to coal, it's about a 4x improvement.

Let's not forget the simple logistical difficulty of using biomass. It is not as energy dense, which makes moving its own weight around more expensive too.

"The net energy ratio between energy output and input was 10.41.. Energy used for hauling hog fuel represented the largest part (36.27%) of the total energy input. The net energy ratio decreased 0.11 with each additional transportation mile

the net energy ratios reported here were on the high end of this range as energy input for possible active drying, storage, and final delivery was not included. " [0]

"The energy content was taken at 137,000 BTUs per gallon for diesel, and 125,000 BTUs per gallon for gasoline (Adams 1983)...

output: the mean HHV ranged from 8,946 to 9,105 BTUs/pound " [0]

A gallon weighs about 6 pounds, so it seems like pound-for-pound (pine-tree) biomass is less than half as productive as gasoline.*

Honestly, I was expecting worse. But over doubling energy costs isn't negligible, especially for poorer countries.

*this is at a glance work, not an actual deep dive

[0] Net energy output from harvesting small-diameter trees using a mechanized system Fei Pan Han-Sup Han Leonard R. Johnson

FOREST PRODUCTS JOURNAL VOL. 58, NO. 1/2 William J. Elliot

When you burn non-renewables, i.e. stuff dug up from the ground, you're adding pollution into the atmosphere.

Pollution that changes the climate.