Carbon capture and storage using wood
It is generally agreed that the earth is warming due to the release of greenhouse gasses due to human activity. Industry is investigating carbon capture from products of burning natural gas and coal by capturing C02 from combustion and storing this gas underground. Gas stored underground may still seep to the surface and be released and this requires suitable geologic formations. This also does nothing about CO2 released by automobiles, airplanes and ships.
In 2013 global emissions of C02 were estimated to be 36 billion metric tons. Slightly less than 1/3 of the weight of a C02 molecule is contained in the carbon atom so Carbon emissions would be slightly less than 13 billion metric tons.
Storing Carbon in a solid form would be much easier. Biochar is a possibility but according to the Biochar page it is uncertain if this would work and the wood used would be partly burned reducing the amount of carbon stored. At least some of the carbon would be returned to the atmosphere after being used by plants or microorganisms as well. The above being said, biochar may still be a worthwhile possibility. Wood naturally contains 50% Carbon by dry weight. The process for storing Carbon in wood is very straightforward:
- Collect wood from either discarded sources such as used building products, discarded furniture etc.
- or Collect wood from fallen trees and remember to replace the nutrients using something such as river silt but be careful not to transport significant pollutants.
- Transport the wood to a location where it will not rot due to climate or other conditions such as deserts or the permanently frozen (so far) high arctic. Placing it in a place where erosion or plate tectonics is depositing material could ensure that it gets buried deeper over time. The exact method of storage would be left up to microbiologists and others with relevant expertise.
This would require 23 billion metric tons of dry wood to defray one year of global emissions at 2013 levels. Since an average tree weighs 70 kg (this number is from Wolfram Alpha and it may be low since a mature tree of most species can be much larger than this but that would be in our favor and reduce the number of trees needed) this would require the equivalent of 3.286 x 10^11 trees per year.
The area of earths forests is 3.856 × 10^13 square meters (Wolfram Alpha.) If we estimate one tree per square meter we have about 3.856 x 10^13 trees so we would require about 0.0085 of the earth's trees or just under the equivalent of 1% of the earths current trees to be stored, however use of used wood would negate the need for removing trees from forests and seeding new forests would speed up the process. Rolling back the Carbon content of the atmosphere to pre-industrial levels would require storing more wood but should be done in order that ecosystems such as coral reefs can recover as much as possible. The atmospheric Carbon content increased from 280ppm to 395 ppm during the Industrial Revolution as of 2013 according to Wikipedia (https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere). That is 29% of 2013 levels. The carbon content of the atmosphere is 720 Gt (http://www.wolframalpha.com) so to remove the additional 29% we need to remove 209.6 Gt of Carbon or 419.2 Gt of wood or 6.0 x 10^12 trees or the equivalent of 16% of the wood in existing forests remembering again that we would likely use reclaimed used wood and can do this over years.
This method is only intended as a short term solution to stop CO2 increases and return levels to normal as we change over to a non-carbon emiting energy system. Using this method we give up soil fertility in the form of nutrients in the wood we store in exchange for also getting rid of atmospheric CO2. We can get away with doing this for a certain amount of time but the less we need to do it the better.
Links[edit | edit source]
A Possible Climate Crisis Management Plan
other numbers from http://www.wolframalpha.com
Desert Reclamation the Easy Way