Name two negative emissions technologies and describe a basic mechanism for each.

• A. BECCS—bioenergy with carbon capture and storage; CO2 produced during bioenergy use is captured and stored underground. Direct Air Capture—removes CO2 directly from ambient air and stores or utilizes it.
• B. BECCS—bioenergy with carbon capture and storage; CO2 released to atmosphere; Direct Air Capture—plants absorb CO2.
• C. BECCS—bioenergy with carbon capture and storage; CO2 is converted to formic acid; Direct Air Capture—CO2 is released.
• D. BECCS—CO2 capture from cement plants; Direct Air Capture—absorb methane.

Answer: (A)

Negative emissions technologies remove CO2 from the atmosphere. Two good examples are BECCS and Direct Air Capture. BECCS combines bioenergy production with carbon capture and storage: biomass grown for energy absorbs CO2 as it grows, and the CO2 released when that biomass is burned is captured and stored underground, yielding a net removal of CO2 if the biomass regrowth and secure storage continue. Direct Air Capture uses engineered systems to pull CO2 directly from ambient air; the captured CO2 is then stored or used in products, providing atmospheric removal regardless of where the CO2 originally came from. The other statements misstate how these technologies work: BECCS does not release CO2 to the atmosphere, Direct Air Capture is not about plants absorbing CO2, and converting CO2 to formic acid or releasing it afterward isn’t the standard mechanism for these NETs.