Natural Gas Production in the Brazilian Pre-Salt and Sustainable Development with the Generation of Blue Hydrogen and Blue Ammonia
Authors: Santos A. F. 
Published: October 2023

Non-renewable sources such as coal, oil and natural gas are currently the most widely used resources in energy generation in the world, representing more than 80% of the energy matrix.

Brazil has its largest oil and natural gas producing region in the Pre-Salt reservoirs. In view of the high gas-oil ratio of the reservoirs, using natural gas as a source for the generation of blue hydrogen and consequently blue ammonia is an important option for sustainable development.

It is an initiative to promote decarbonization, based on the use of the component with the greatest presence in natural gas after the removal of contaminants, especially CO2 (carbon dioxide), which is methane (70%). In this sense, stationary production units should incorporate processes aiming at the transformations necessary to obtain blue hydrogen and blue ammonia.

Methane (CH4) is one of the gases that most influences the increase in the greenhouse effect, even though it has a much lower volume in the atmosphere when compared to the presence of carbon dioxide. In equal volumes, methane generates about 28 times more global warming than carbon dioxide. Due to this characteristic, it is the gas, following carbon dioxide, that most contributes to the increase of the greenhouse effect. Thus, actions to reduce their emissions in the atmosphere will curb the temperature rise.

For this purpose, the stationary production units must provide for carbon dioxide separation processes present in natural gas, separation of methane for internal consumption with calorific energy generation and transformation into electricity, injection of natural gas into reservoirs with carbon dioxide and methane remaining, and finally, transport, by pipeline, of methane-free natural gas to natural gas processing plant.

In addition to meeting the operational activities of the stationary production units the electric energy must be applied in the electrolysis of seawater generating blue hydrogen, so called was originated from the burning of methane (fossil fuel) which will react with nitrogen captured from atmospheric air and will result in blue ammonia.

On the other hand, it will not be the dimensions and structures of the stationary units, the insertion of investment costs and the increase in operating costs, in addition to safety factors that should limit or prevent the implementation of this offshore alternative as a sustainable energy source.

The use of support vessels for the installation of complementary equipment includes, mainly, those necessary for the production process of hydrogen and ammonia important, because it will have as fundamental functions the storage and transport and blue hydrogen and blue ammonia. Therefore, it should be an integral part of the process beyond the stationary production units being part of the studies of technical and economic feasibility, observed by the physical and chemical characteristics and properties of the products (blue hydrogen and blue ammonia).

Sustainable development is an incentive to the production, storage and maritime transport of blue hydrogen and blue ammonia providing mobilizations and deliveries of clean energy, enhancing the creation of corridors and maritime terminals to reach and to provide industrial segments of low decarbonization.

Both fuels can be used individually and prorated to their volumes according to the needs of the consumer media. For example, the transport of blue hydrogen can carry the fuel cells of the vessels, while blue ammonia can be consumed as liquid fuel, with the largest volume being transported to the final consumers.

Hydrogen is one of the main sources of clean energy generation. In the liquid state, the volume of the hydrogen is hundreds of times smaller than the gaseous state, however, its liquid state is only reached and maintained at temperatures below -253°C (cryogenics).

The amount of ammonia transported in the maritime environment is the limited, however, it is a source of clean energy demanding consumption in Europe, Japan, and China. Its great difference compared with hydrogen is the ease of reaching the liquid state whose lowest temperature is –77.73◦ C.

The chemical reaction N2 + 3 H2 → 2 NH3 is convertible, that is, ammonia (NH3) can generate hydrogen (H2) and nitrogen (N2), a factor of great flexibility for energy efficiency and systematic transport and consumption.