Bio-Energy with Carbon Capture and Sequestration (BECCS)

BECCS encompasses a wide range of different plans, but what they all share in common is the utilization of plants to draw CO₂ from the atmosphere (which they have perfected over millions of years) and then using the biomass to generate power. In one version, the plant material is fermented to yield biofuels like ethanol, but when the ethanol is burned, it releases the CO₂ back into the atmosphere — this is not going to result in negative carbon emissions. But in another form, a BECCS scheme combusts the biomass to electrical energy in a power plant equipped with CO₂ scrubbers on their emissions.

A schematic representation of a BECCS system, which utilizes fast-growing plants to remove CO2 from the atmosphere, turning it into biomass that is harvested and burned in a power plant to produce electricity. The combustion emissions are scrubbed to remove the CO₂, which is then sequestered in a suitable geologic formation below the surface.

Click for a text description of Bio-Energy with Carbon Capture and Sequestration diagram.

The image is a flowchart diagram illustrating the process of Bio-Energy with Carbon Capture and Storage (BECCS). Here's the step-by-step description:

Atmospheric CO₂: Represented by a green arrow labeled "Atmospheric CO₂" pointing downwards, indicating that CO₂ from the atmosphere is absorbed by plants.
Biomass (Trees): On the left side, there is an illustration of a forest or group of trees, representing biomass. These trees absorb CO₂ from the atmosphere through photosynthesis.
Harvest: A green arrow labeled "Harvest" leads from the trees to the next step, indicating that the biomass (trees) is harvested.
Biomass Burning Power Plant: The harvested biomass is directed into a blue structure labeled "Biomass burning power plant." This plant burns the biomass to generate electricity.
Electricity to Grid: From the power plant, there is an arrow leading off to the right labeled "Electricity to grid," indicating that the electricity generated is supplied to the electrical grid for distribution.
CO2 Scrubbed: A yellow arrow labeled "CO₂ scrubbed" exits from the power plant, showing that the CO₂ produced during the burning of biomass is captured instead of being released into the atmosphere.
Mixer: The CO₂ is then directed to a gray oval labeled "mixer." Here, the captured CO₂ is mixed with water, indicated by a blue arrow labeled "water" entering from the right side.
CO2-Water Mixture: A green arrow labeled "CO₂ + water" leads from the mixer downwards.
Storage Rock: At the bottom, there is a label "Storage Rock," indicating that the mixture of CO₂ and water is sequestered into geological formations (storage rock) for long-term storage.

This diagram visually represents the process where biomass (trees) absorbs CO2, is harvested, burned for energy in a power plant, and then the CO2 emissions from this process are captured, mixed with water, and stored underground, effectively removing CO₂ from the atmosphere.

The captured CO₂ from these power plants is then injected into a deeply buried geologic layer, where it is sequestered — just as with the DACCS approach. A BECCS system will reduce the amount of CO₂ in the atmosphere while at the same time producing energy, the sale of which helps offset the costs. Some estimates suggest that a system such as this could remove carbon at a net cost of \$15 per ton of CO2 — significantly cheaper than the DACCS systems (which might get to \$100/ton in the near future).

Deploying BECCS on a large enough scale to make a serious reduction in CO₂ would require a lot of land and water to grow the biofuels, and this imposes a limit since we will also need the land and water resources to grow food crops for a growing population. One estimate suggests that in order to remove 12 GT of CO₂ from the atmosphere each year, we would need to commit an area equal to one third of the present cropland area to BECCS, and we would need perhaps one half of the water currently used by agriculture. These are some pretty serious environmental constraints!

Nevertheless, BECCS holds great promise for being an important part of a negative emissions strategy that we will need to dramatically lower our net carbon emissions.