Carbon Dioxide Removal.
The world needs to remove between 100 and 1000 billion tons of CO2 before 2100
The world has delayed reducing carbon emissions for so long that humanity will need to suck enormous amounts of carbon dioxide back out from the air to avoid catastrophic global warming. Humans have added around 1 500 billion tons of CO2 to the atmosphere since the burning of fossil fuels for energy began with industrialization. Now, to manage the Paris goals we need to aggressively cut carbon emissions AND permanently remove up to around 1 trillion tons of CO2 between now and 2100.
Options of Carbon Removal Technologies.
Direct Air Capture (DAC)
A process that removes CO2 from ambient air and concentrates it for storage deep underground or use in a wide variety of products.
Geological Storage: the injection of CO2 into a geologic formation deep underground for essentially permanent timescales. This activity is not considered a CDR approach by itself, but rather, is a way of safely storing carbon removed from the atmosphere through DAC and BECCS.
Bioenergy with Carbon Capture and Storage (BECCS)
Biomass feedstock is converted to electricity, hydrogen, heat, and/or liquid fuels. The process simultaneously separates and stores some portion of the carbon dioxide which is released in the process in deep geological formations below the earth's surface.
Afforestation and Reforestation
Involves growing new forests in places where they did not exist before (afforestation) or restoring forests in areas where they used to grow (reforestation). Other land management practices designed to increase the quantity of carbon stored in forests, or other ecosystems such as wetlands, relative to baseline conditions (e.g., by modifying harvest schedules) may also be considered. The carbon storage is highly sensitive to policy changes and thus reversible. So-called "coastal blue carbon involves increasing carbon in standing biomass and, in particular, in soils in mangroves, tidal marshes, seagrass meadows, and other coastal habitats.
Enhanced soil carbon sequestration
The use of land or altered agricultural practices to increase the soil organic carbon (SOC). The carbon storage is highly sensitive to policy changes and thus reversible.
Biochar
Biochar is produced when biomass is thermally converted in an oxygen-depleted atmosphere. This process is called pyrolysis and takes place at temperatures up to around 600° C. During this process three products are generated in different ratios depending on process design: a carbon-rich solid i.e. biochar, a gas (syngas) and a liquid (bio-oil). Biochar can then be used to enrich agricultural lands and consequently fixing carbon by keeping a large portion of the carbon in soil for hundreds of years preventing the return of biotic carbon to the atmosphere via decomposition and, therefore, serving as a carbon sink.
Enhanced weathering
CO2 mineralization processes by which certain minerals react and form a bond with CO2, removing it from the atmosphere and resulting in inert (stable) carbonate rock.
Ocean Fertilisation
Ocean fertilization enhances biological production, and thereby carbon uptake, deliberately adding essential nutrients to the upper waters where these are in short supply. One proposed approach builds on fertilization with the macronutrients nitrogen and phosphorus, another involves addition of iron to the open ocean.
