CO₂ convert sustainably into methanol

What about the global warming that is subject for discussion everywhere?

Regardless of whether or not carbon dioxide (CO₂) emissions contribute to global warming, it is undisputed that human actions create enormous amounts of carbon dioxide (CO₂).

Unclear is however how much carbon dioxide (CO₂) is released to the environment totally and how much carbon dioxide is the result of human activities.

How much carbon dioxide can our planet manage when it comes to decomposing carbon dioxide naturally or converting it into oxygen and biomass by photosynthesis processes?

The knowledge about emission sources of carbon dioxide and its temporal quantities allows conclusions about the reasons for global warming and the influence of human activities.

It is a matter of fact that we are observing a change of climate during the recent decades. We should take such observations serious if we want to preserve the habitat on our planet on a long term basis and in a sustainable manner.

Do we consider the photosynthesis process of green plants and trees in nature that convert significant amounts of carbon dioxide to biomass and oxygen, then their protection appears as an major aim by all countries all over the world.

How can carbon dioxide be avoided or reduced to a tolerable level?

Do there exist applicable processes that allow the conversion of carbon dioxide into other valuable materials?

This blog post describes a process for the chemical conversion of carbon dioxide to methanol, which is referred to as "methanol synthesis".

"Methanol synthesis" is a process that allows among other the conversion of carbon dioxide to methanol by reaction with hydrogen and by using suitable catalysts.

Methanol itself is an important commodity for the chemical industry, from which numerous highquality chemical products can be produced. Additionally, Methanol represents a fuel that could be used in conjunction with mobility.

The installation of an appropriate “Methanol Synthesis Plant” should be considered in close proximity to facilities with significant emission sources for carbon dioxide.

This applies, for example, to power plants, chemical and petrochemical plants or other industrial plants. Usually, these industrial plants require enormous demands for thermal energy, which will be covered by the combustion of fossil or renewable raw materials.

The hydrogen required for carbon dioxide conversion could be generated by water electrolysis. The electric power required for water electrolysis can be provided by excessive renewable energies (wind, water, sun).

Thus, methanol could be produced sustainable.

The following equation of reaction illustrates the process of water electrolysis that splits Water into Hydrogen and Oxygen. The 2nd equation of reaction illustrates the process of methanol synthesis, at which Methanol is formed from Carbon Dioxide and Hydrogen. The process of methanol synthesis represents an exothermal reaction.

2H₂O → 2H₂ + O₂
CO₂ + 3H₂ ↔ CH₃OH + H₂O

Considering the molecular weights for aforesaid equations of reactions and a complete conversion of its educts to reaction products, there would be required 9 kg Water (H₂O) for the generation of 1 kg Hydrogen (H2). 8 kg Oxygen (O₂) would be generated as by-product.

The generation of 1 kg Methanol (CH3OH) would require 1,3750 kg Carbon Dioxide (CO₂) and 0,1875 kg Hydrogen (H2) theoretically. Simultaneously, there would be created 0,5625 kg Water (H₂O) as by-product that, theoretically could be reused for water electrolysis process.

For a better illustration, a heating system of German home built in the middle of the 80s is considered in a 1st example. Home’s heating system is used for heat supply and generation of hot water. Fuel oil “Heizöl EL” is considered as heating material, whereby 3.000 liters per year are consumed.

„Heizöl EL“ fuel consist of 86 … 88 wt.% of Carbon (C) and 12 … 14 wt.% Hydrogen (H). Traces of Nitrogen (N) and Sulfur (S) are neglected. The average mass density of “Heizöl EL” fuel amounts to approx.. 840 kg/m³ at 15 °C. Thus, 3.000 Liters “Heizöl EL” fuel equals to 3,00 m³ or 2.520 kg.

Considering aforesaid composition, „Heizöl EL” fuel would contain 2.192 kg chemically bound Carbon (C) and 328 kg chemically bound Hydrogen (H).

The following equations of reactions illustrate the oxidation of Carbon (C) to Carbon Dioxide (CO₂) as well as the oxidation of Hydrogen (H2) to Water (H₂O) and represent the combustion of “Heizöl EL” fuel.

C + O₂ → CO₂
H₂ + ½ O₂ → H₂O

The oxidation of 2.192 kg Carbon (C) require 5.845 kg Oxygen (O₂) and result in 8.037 kg Carbon Dioxide (CO₂). The oxidation of 328 kg Hydrogen (H2) require 2.624 kg Oxygen (O₂) and result in 2.952 kg Water (H₂O).

Assuming that 8.037 kg Carbon Dioxide (CO₂) result by the combustion of 3.000 Liters „Heizöl EL“ fuel and that can be converted into Methanol (CH3OH), there could be produced 5.845 kg Methanol (CH3OH) theoretically.

Above mentioned example illustrates the annual average amount of Carbon Dioxide (CO₂) that is created by one home in Germany where “Heizöl EL” fuel is used for heat supply and hot water generation.

In comparison, an average-sized tree (e.g. beech) can convert an average of 12.5 kg of Carbon Dioxide (CO₂) per year only. This means that 643 trees (beech) are required to neutralize carbon dioxide emissions of an individual home. Imagine the forest area that the owners of a home would have to plant and to maintain to compensate carbon dioxide emissions generated by their home’s heating system.

A 2nd Example considers a technical unit for process heat supply of an industrial facility with a heat transfer capacity of 3.000 KW (equals to 3,0 MW)

There is assumed a technical unit for heat supply with a firing efficiency of approx. 90 %.

This amounts to a firing duty of 3.333 KW. “Heizöl EL” fuel will be considered again for the generation of heat supply. “Heizöl EL” fuel’s lower caloric value amounts to 42.000 kJ/kg.

Considering a 24/7 operation and 8.000 operating hours per year, the unit for heat supply would consume 285,71 kg/hr respectively 2.289 tons/a.

Assuming that the composition of “Heizöl EL” fuel is the same as this was considered in 1st example, then 7.301 tons of Carbon Dioxide (CO₂) would be created per year by such industrial firing unit. 5.310 tons methanol could be produced from 7.301 tons Carbon Dioxide (CO₂) theoretically.

A tree population of 584.080 trees is required to break down this amount of Carbon Dioxide (CO₂), assuming that a tree (e.g. beech) can convert approx. 12.5 kg of Carbon Dioxide (CO₂) annually.

A 3rd Example will illustrate the Carbon Dioxide emissions of a human while “breathing out”

The amount of Carbon Dioxide (CO₂) contained in the exhaled air is approx. 4 % by volume.

Depending on the human’s activities (e.g. resting phase, normal phase or high performance phase), the amount of exhaled air varies from approx. 5 ... 50 Liter/min. At human's normal day that considers a rest phase, a normal phase and a high performance phase, about 30.000 liters of air are exhaled with a Carbon Dioxide content of 4 vol.%. This represents 1.200 Liter Carbon Dioxide. At a mass density of 1,77 kg/m³ (@ 30 °C exhale air temperature), 2,124 kg Carbon Dioxide are exhaled to the environment by a human per day. Thus, 775 kg Carbon Dioxide (CO₂) are exhaled to the environment by a human per year.

A tree population of 62 trees is required to break down this amount of Carbon Dioxide (CO₂), assuming that a tree (e.g. beech) can convert approx. 12.5 kg of Carbon Dioxide (CO₂) annually.

The examples considered above illustrate the quantities of Carbon Dioxide (CO₂) released to the environment by the respective emission sources. The examples can be continued indefinitely and demonstrate the Carbon Dioxide emissions caused by humans to the environment.

An increase in average global warming of 1,5 °C should be considered like an increase in human's temperature (38.5 °C =Fever). How does a human feel in such case?

This blog post leaves it up to reader's imagination to decide what effects and challenges humans will have to face in the future if we continue as this was done in the past.

We need our planet - does our planet need us?

The next blog post will discuss the fuel cell technology that represents among other an alternative concept to maintain our mobility. Another application could be „Combined Heat and Power Unit“ that might be used in buildings in conjunction with installed photovoltaic system and where excessive electrical power can be converted into Hydrogen.