A lot of articles have been written and published that select a few factors relevant to climate and then do some number crunching to support a preconceived notion. It's like political economics where ways are sought to make a desired policy add up. It never works out as predicted, but accurate prediction isn't the point. For example:

A new study finds that it will take more than 75 years for the carbon emissions saved through the use of biofuels to compensate for the carbon lost when biofuel plantations are established on forestlands. If the original habitat was peatland, carbon balance would take more than 600 years. . .

Conversion of forest to oil palm also results in significant impoverishment of both plant and animal communities. Other tropical crops suitable for biofuel use, like soybean, sugar cane and jatropha, are all likely to have similar impacts on climate and biodiversity.

"Biofuels are a bad deal for forests, wildlife and the climate if they replace tropical rain forests," says research scientist Finn Danielsen, lead author of the study. "In fact, they hasten climate change by removing one of the world's most efficient carbon storage tools, intact tropical rain forests." . . .

According to the study, reducing deforestation is likely to represent a more effective climate-change mitigation strategy than converting forest for biofuel production, and it may help nations meet their international commitments to reduce biodiversity loss.

Alternatively, planting biofuels on degraded grasslands instead of tropical rain forests would lead to a net removal of carbon from the atmosphere in 10 years. Any biofuel plantations in tropical forest regions should be considered only in former forest land which has already been severely degraded to support only grassy vegetation.

I agree that biofuels are a bad idea, especially in places like Indonesia where peat bogs are burned as part of field preparation for palm oil plantations and the like. But it is a mistake to imagine that using grasslands to grow biofuel crops, even when they where once forest lands, is better. When those lands are repurposed for biofuels it drives existing users into the forest for more land.

No matter how you slice it growing crops specifically for fuels increases pressure on forests. The only way that biofuels can be positive is when they are made from agricultural byproducts, and only when those byproducts do not have higher value as soil amendments to grow more crops.

There is an exception. It may be that there are aquatic sources of biofuel feedstocks that do not harm the environment. High oil algae grown on waste water bodies may be OK.

It would also be smart to renovate the grasslands since healthy perennial grasslands increase in soil organic matter for decades. This sequesters carbon as well or better than forests while also producing a forage crop and habitat for many species.