Without compromises during the introduction phase, the gardener would determine how many giga tons of CO2 may be emitted per year in order to effectively slow down the greenhouse effect by 2050, e.g. 15 giga tons. These 15 giga tons are to be purchased by the total budget of 8.4e13 REU for mankind (see 8).
This results in a price of 5.6 REU per kilo of CO2 (8.4e13 REU / 15e12 kg). In other words, with the available REU budget, we can pay as much CO2 emissions as are allowed to meet the climate target. Each one should produce 12,000 REU / 5.6 REU per kg of CO2, which is equivalent to the 2000Kg of CO2 found in the literature.
At the moment, however, much more CO2 is emitted and the gardener has to accept a compromise. Instead of the 15 gigatons, it will start with the global 34.5 giga tons of CO2 emissions from a reference year 2012  to the point of being a good man. This results in a price of 2.43 REU per kilogram of CO2 (8.4e13 REU / 34.5e12 kg). But please note: This price is too low and would make the much too high 34.5 giga tons of CO2 possible.
The gardener has to bring this special price of 2.43 REU closer to the real price (5.6 REU per kilo CO2) within a few years, so that we have to reduce CO2 emissions.
But even with this advantageous price some frightening concluseion can be recognized and the ecological dimension of our CO2 footprint get apparent:
Even more worrying is the fact that per capita annual emissions in India are only 1600 kg CO2, i.e. an Indian would have to pay a total of 3888 REU (1/3 of his budget) per year for his CO2 emissions, but would have an unused budget of 12,000 - 3,888 REU = 8,112 REU at the end of the year. He could sell this REU amount to other people who cause more CO2 emissions. However the REU total budget cannot be exceeded.
Lignite versus photovoltaics can also be compared well in REU:
According to  a kilowatt hour of brown coal electricity has production costs of about 6.3ct on average and causes a CO2 emission of 0.36kg i.e. 0.87 REU.
Photovoltaic installations have production costs of 9.39 ct / kWh (average small plant) and produces about 0.05Kg CO2 / kWh, i.e. 0.12 REU.
This makes it clear how advantageous ecological energy sources will be:
6.3 ct / 0.87 REU or 9.4 ct / 0.12 REU. The choice shouldn't be difficult.
The price advantage could lead to a higher classic price being charged for green electricity. To a certain extent, this would even be desirable, since investments in regenerative technologies should also be worthwhile.