Cactus cactus should also be considered an excellent source of carbon credits, it can be successfully applied on very cheap or donated land. The cost of implementation is similar to any other plantation and also requires technified irrigation.
Basically there are two alternatives voluntary bonds, are those in which companies concerned about the environment agree to finance these carbon sequestration projects. And the second alternative are mandatory when a state forces a polluting company to offset carbon dioxide emissions.
Carbon offset projects require at least 1000 hectares, the costs of studies, monitoring, protocol are the same regardless of size.
In the case of agro-industrial projects we have two alternatives to apply for carbon credits.
1. Bonds for plantations
The nopal is a great biomass producer, in plants of high densities it is not complicated to reach 1.000 tons of biomass per year,
In the process of photosynthesis the plant captures carbon dioxide which is transformed into chemical components of carbon chain.
These chemical bonds in the fermentation process are destroyed by anaerobic bacteria, releasing their energy and then expelling waste in this case carbon dioxide and methane as part of their metabolism.
In energy crops it is well known that the balance is carbon neutral or slightly negative, in a cactus crop maybe 98 - 99 % of the plant is transformed into energy, but always a fraction are non-digestible elements such as fibers, lignin, which are incorporated into the soil.
If we do the calculations we have:
1 hectare produces 1.000 ton fresh nopal per year
Solid content 13 %
The structures formed are basically carbon chains with hydrogen, the solid content is 130 tons, 100 - 115 tons are elemental carbon, this is very simple to determine in a laboratory.
When performing the chemical balance we have that every 12 gr/mol of carbon it was necessary to sequester 44 gr/mol of carbon dioxide from the air.
100 ton carbon = x ton carbon dioxide
12 gr / mol carbon 44 gr / mol carbon dioxide
With this ratio we have that 1 hectare can sequester 366 tons of carbon dioxide per year.
The value of carbon credits varies in each country, in Europe it has a value of €70/ton, the industry has already defined how much it is willing to pay and its values
"In the absence of global measures, at Repsol we have established an internal carbon price that we apply to every new investment we undertake. Within the European Union, the values we have set are US$70/t in 2025, reaching US$100/t from 2030 onwards. In the rest of the countries we will consider a price of 60US$/t from 2025." (Repsol)
A hectare with these values produces 366 ton/ha x 70 US = 25.620 US
Simulating a 2.000 hectares for carbon credits
At 2.000 hectares would be US 51,240,000 which is equivalent to 46,897,922 euros (11/03/2024) This corresponds to the income per year by sequestering carbon.
In this case the crops are dedicated only to capture carbon credits without use as energy
2. Bonus crops for energy.
This alternative is a dual-use plantation, crops are developed to produce biogas and its transformation into electrical energy or direct use as fuel.
Calculations based on a production of 1.000 tons / hectare are similar.
1.000 ton fresh biomass = 130 ton dry basis + 870 ton water
In the biodigestion process the cells of the cactus are destroyed which releases the water from the cactus.
1 ton dry = 450 m3 methane 65 %
130 dry ton = 58.500 m3 methane 65% (reactor output)
The calorific value of natural gas : 39.957 KJ /m3 (9,550 kcal/m3).
Diesel's caloric power : 42.600- 43,200 KJ/ kg
Heating power of 1 hectare = 58,500 m3 x 0.65 % x 39,957 kJ/m3 = 1,519,364.925 KJ
If we use the average caloric power of oil: 42.900 KJ/kg
We obtain that 1 hectare replaces the equivalent of 1.519,364,925 KJ / 42,900 KJ/Kg = 35,416 kg of diesel
The density of diesel = 0.85 kg / liter.
35.416 kg of diesel equals 41,666 liters diesel.
One liter of diesel creates 2.68 kg of CO2 in combustion. Therefore, we can simply multiply the number of liters consumed by 2.68 to find out how many kilograms of CO2 equivalent
Thus we have: 41.666 liter x 2.68 kg / liter = 111.665 kg carbon dioxide
One hectare replaces the emission of 111.66 Tons carbon dioxide/ hectare x 70 US/ton = 7.816 US/hectare
On 2,000 hectares would be US 15,632,000 which is equivalent to 14,308.985 euros (04/03/2024)
Income from this is significant after the third year of growth.
In addition, the energy produced also has an income.
In a 2,000 hectare project the annual income from Biogas sales is double compared to the income from carbon credits sales.
When adding the revenue from carbon credits and energy the revenue is similar to just planting cacti and selling the carbon credits.
3. Certification
In the world there are several institutions dedicated to carbon credits, however, we should always give preference to those that are located in the country of project development, this will keep the cost of the studies at a more reasonable value, in addition to knowing the internal bureaucracy.