Complex sentence: The carbon released into the atmosphere from the combustion of biogas has been removed by plants for them to grow in the recent past, usually within the last decade, but more typically within the last growing season.
Split into simpler sentences: The carbon released into the atmosphere from the combustion of biogas has been removed by plants in order for them to grow in the recent past. This could have occurred within the last decade, but more typically within the last growing season.