How Is Your Offset Achieved?
Many offset providers count the carbon absorbed by the growth of a tree as a carbon offset. While it is true that trees absorb carbon as they grow it is not as clear precisely how much nor for how long over their lifetime the trees continue to absorb AND store carbon.
Due to the inherent uncertainties we have elected not to count the carbon from the growth of the Jatropha trees in our calculations. Instead we have chosen to focus on the produce of the trees. Jatropha trees produce a seed that can be pressed to produce an oil that can be converted to biodiesel. The residue from that pressing process leave a material called seedcake that can be used as fertilizer. Any left over biomass from the harvesting as well as biomass from pruning the trees can be converted into briquettes and used as a solid fuel. This solid fuel can be used at home in place of liquified petroleum gas (LPG) for cooking or used in industrial applications requiring high temperatures.
As a company we have decided to calculate only what we can be certain of, and to disregard any additional carbon or carbon equivalents we cannot precisely measure.
According to our research we can expect a crop of Jatropha trees to produce 7.5 tons of seed per hectare per year. When the seeds are pressed 30% of the weight is extracted as oil giving us 2.25 tons of oil per hectare. This oil is converted into biodiesel. The conversion process from oil into biodiesel is not 100% efficient and it is expected that for every 1 liter of crude Jatropha oil we should produce about .9 liter of biodiesel.
In order to allow a safe margin of error we calculate based on 80% efficiency; resulting 418.448 gallons of biodiesel per hectare. This displaces an equivalent amount of diesel resulting in the prevention of 4247.252 kilos per hectare of new carbon dioxide into the atmosphere. The displacement occurs because the carbon released from the combustion of biodiesel is the same carbon the tree absorbed while it produced the seeds. It is part of the existing carbon cycle, or recycled carbon. It neither increases nor decreases the total amount of carbon dioxide present in the atmosphere.
In comparison when traditional petroleum based diesel is combusted the carbon released is NEW carbon. carbon that was locked away underground for thousands of years and is just now NEWLY being released into the atmosphere, increasing the overall amount of carbon dioxide present in the atmosphere. By using biodiesel we displace ordinary diesel and prevent that NEW carbon from entering the atmosphere, preventing an increase in the total carbon dioxide in the atmosphere.
The remaining mass left over after pressing the seeds amounts to 5 tons of what is called seedcake. After being processed the seedcake results in 2.5 tons of fertilizer per hectare per year being produced. Seedcake fertilizer must be used in higher quantities per hectare than organic fertilizer but at a much lower cost to the farmer.
Inorganic nitrogen fertilizer are presently made using fossil fuels such as natural gas and contain approximately 45% nitrogen by weight, but it is not the nitrogen that is a problem for global warming, it is the nitrous oxide created by the nitrogen. The Intergovernmental Panel on Climate Change uses a default value of 1.25 percent of fertilizer nitrogen inputs are lost as nitrous oxide. Nitrous Oxide is 310 times as potent as carbon dioxide for global warming. One ton of Nitrous Oxide is equal to 310 tons of Carbon Dioxide.
One kilo of inorganic fertilizer releases just a small amount of nitrous oxide: only 0.005625 kilos but multiplied by its global warming potential of 310 and one kilo of inorganic fertilizer releases 1.743 kilos of NEW carbon dioxide equivalent (in the form of nitrous oxide) into the atmosphere. This does not count the carbon released in the manufacture of the inorganic fertilizer.
Seedcake fertilizer must be used in higher quantities than inorganic fertilizers, for example a field requiring 300 kilos of inorganic fertilizer would require 4 tons of seedcake fertilizer or 13.33 times as much, but at a much lower cost to the farmer. Per hectare of Jatropha the production of seedcake fertilizer is approximately 2.5 tons after preparation. A hectare of Jatropha will produce enough seedcake for fertilizer to displace 187.5 kilos of inorganic fertilizer and the 326.953 kilos of new carbon equivalent it will release into the atmosphere in the form of carbon.
Per hectare of Jatropha there is also produced 4 tons of solid biomass waste per year. This biomass can be converted into charcoal briquettes for use in residential applications like cooking or industrial applications. The biomass is converted into charcoal briquettes at an efficiency of 25% by volume resulting in 1 ton of charcoal briquettes produced per hectare of Jatropha.
The charcoal briquettes displace other types of fuel such as liquefied petroleum gas (LPG) or other forms of fuel as well as preventing the stripping of existing forests to produce charcoal; it is estimated that for every ton of charcoal briquettes produced, at least 75 trees are saved. By preventing these activities the charcoal briquettes also prevent the associated release of new carbon dioxide and equivalent gases into the atmosphere. Counting the avoided emissions depends heavily on the method of producing the charcoal briquettes and the fuel being displaced by its use. Estimates range from as low as 0.2 kilos per kilo of briquettes produced to as high as 14 kilos per kilo of briquettes produced.
GroPower has taken the decision to consider only the low side, worst case estimates and count only 0.2 kilos per kilo of briquettes produced. This results in another 200 kilos of carbon offset achieved per hectare. So the total carbon offset achieved per hectare of Jatropha is 4774.205 kilos of carbon offset per hectare per year.
It is important to note as mentioned above that every 1 ton of charcoal briquettes produced avoids 75 trees from being cut down and keeps the carbon they have stored safely locked away. This could account for as much as 10 additional tons of carbon preserved for every hectare of Jatropha planted. We do not include this in our calculations however because of the difficulties in accurately measuring the amount of carbon in a living tree. Instead we take comfort from knowing we are helping protect old growth forests and that our plantations operate on a zero waste policy using every kilo of biomass produced to a good and useful end.
GroPower is a DBA name of AMCG Ltd.,
a registered company of England and Wales. Registration No. 5136786
Tel. No. +44 207-193-2160 | Email (regarding GroPower): gropower@amcgltd.net
