BIOMETHANE


Biomethane is a gaseous biofuel obtained from biogas processing. In turn, biogas originates from the anaerobic digestion of organic material (decomposition by action of bacteria), composed mainly of methane (CH4) and carbon dioxide (CO2).

It is produced from organic products and wastes agro-forestry, agricultural residues, animal manures, domestic sewage and urban solid wastes (sanitary landfills).

1Biomethane from organic waste

Biomethane obtained from essentially organic waste is that from agro-forestry activities or from certain commercial activities (e.g. food discarded by bars and restaurants), excluding landfill gas and from sewage treatment plants, since these may contain other non-organic wastes.

After the biogas purification steps, a gaseous fuel (biomethane) with a high content of methane in its composition, resulting in characteristics that makes it interchangeable with natural gas in all its applications or capable of being transported in the form of gas compressed by means of a truck-beam (virtual pipeline). The quality of biomethane is regulated with different standards depend on each country.

In case of Brazil is regulated through government resolutions as follow: ANP Resolution 8/2015 and ANP Resolution No. 685/2017. The first deals with the specification of biomethane from agrosilvopastoral and commercial organic products and wastes; the other deals with the specification of biomethane from landfills and sewage treatment plants.

2Application of biomethane as an alternative to partially substitute diesel

Biogas, after purification and compression, can be used as a fuel gas instead of diesel, extracted from non-renewable resources.

In order for the produced biogas to be used in diesel-powered engines, it is necessary to follow an industrial biogas process. This process consists of:

• Extract the sulfuric gas (H2S) and the humidity (H2O) from the biogas.

• Eliminate possible undesirable gases within the biogas, such as ammonia (NH3), oxygen (O2), hydrogen (H2) and nitrogen (N2).

• The gas resulting from the steps of the above process will be a gas composed basically of methane gas (CH4) and carbon dioxide (CO2).

• In this step it is necessary to separate the methane gas (CH4).

• Compress the methane gas (CH4) at a pressure of 250 bar, so that it can be transferred to cylinders adapted to diesel powered vehicles.

The carbon dioxide (CO2) separated in the process can be burned or stored for later sale.

It should be noted that diesel replacement is not total and requires an engineering adaptation in diesel trucks. The diesel cycle engines will be adapted to function as a bi-fuel vehicle (diesel and methane). The diesel fleet will use a compound that may have from 40% to 100% diesel, or from 0% to 60% methane (CH4). The mixture will always have a diesel content.

The diesel fleet will use a compound that may have from 40% to 100% diesel, or from 0% to 60% methane (CH4). The mixture will always have a diesel content.

The advantages of this transformation go beyond financial costs, encompassing environmental liabilities and the possible lack of diesel.

The calorific equivalence of one litre of diesel with one m3 of biomethane equals 1.

3Application of biomethane as an alternative to CNG (natural gas vehicles)

Biogas, after purification and compression, can be used as a fuel gas instead of CNG (natural gas vehicle), extracted from non-renewable resource.

In order for the biogas produced to be used in Otto Cycle engines (gasoline and ethanol cars), it is necessary to pass the biogas through an industrial process. This process consists of:

• Extract the sulfuric gas (H2S) and the humidity (H2O) from the biogas.

• Eliminate possible undesirable gases within the biogas, such as ammonia (NH3), oxygen (O2), hydrogen (H2) and nitrogen (N2).

• The gas resulting from the steps of the above process will be a gas composed basically of methane gas (CH4) and carbon dioxide (CO2). In this step it is necessary to separate the methane gas (CH4).

•Compress the methane gas (CH4) at a pressure of 250 bar, so that it can be transferred to the adapted cylinders in vehicles driven by gasoline and / or ethanol.

The carbon dioxide (CO2) separated in the process can be burned or conditioned and stored for later sale.

It is worth noting that methane (CH4) replacement of NGV is direct and total and requires a simple engineering adaptation in automobiles and / or vehicles.

NGV is actually the natural gas of oil, after cleaning and compression and in turn methane (CH4) is the main component of natural petroleum.

Many people and companies adopt the transformation of Otto Cycle engines, aiming at the financial cost, mainly Taxis fleets in regions where NGV is abundant and cheap as the state of São Paulo.

The advantages of this transformation go beyond financial costs, encompassing environmental liabilities and the possible lack of Gasoline or Ethanol.

The calorific equivalence of one litre of NGV with one m3 of biomethane equals 1.

4Application of biomethane for combined generation of electric and thermal energy and sales of commercial CO2.

Biogas, after purification, can be used as fuel gas for the generation of electric and heat energy in Otto Cycle engines powered by biogas. These motor-generators are specially developed to operate the biogas explosion.

In order for the produced biogas to be used in Otto cycle biogas engines, it is necessary to pass the biogas through an industrial process. This process consists of:

• Extract the sulfuric gas (H2S) and the humidity (H2O) from the biogas.

• Eliminate possible undesirable gases within the biogas, such as ammonia (NH3), oxygen (O2), hydrogen (H2) and nitrogen (N2).

• The gas resulting from the steps of the above process will be a gas composed basically of methane gas (CH4) and carbon dioxide (CO2). In this step it is necessary to separate the methane gas (CH4).

The gas resulting from the steps of the previous process is biomethane (methane CH4) and will directly feed the exclusive engines to Natural Gas and no adaptation is necessary.

The advantages of this alternative of using biomethane (natural gas) engines are many, such as availability, low cost and diversity of engine models available on the market. In addition, a maintenance (OPEX) much smaller than the usual engines to biogas.

Another indirect advantage is the application of carbon dioxide (CO2) in the process, which can be stored for later sale to the industry. Or it can still simply be burned.

These combined heat and power (CHP) combined heat and power (CHP) units have many suppliers around the world (Caterpillar, GE, Cummins, Scania, MAN, Volvo and others).

The Otto Cycle engine powered by biogas has an electricity generator coupled to its axis. The torque of the motor rotates the generator, which in turn produces electricity. Power generation is constant as long as the motor is powered and fully operational.

These motors are designed to run 8,000 hours in a year and usually achieve a superior energy efficiency of 91%. The electric efficiency of these engines’ ranges from 38-41%. The thermal efficiency of these engines, the capacity to generate thermal energy, would come from 40-43%.

As every Otto cycle engine runs by explosion, a large amount of heat is released, by the "exhaust" of the gases from this explosion and by the block engine. Recovering this heat from the "exhaust" and "engine block" and utilizing them internally in productive processes of the biogas plant or the industry where the plant is installed is perfectly feasible from a financial and technical stand point.

However, this study is specific to the conditions of each installation, making it difficult to quantify theoretical cases.

For example, the electric energy generated by 500 m3 per hour of biogas (being the biogas with 55% of CH4) is 1.13MWh. The total produced heat energy is 1.22MWh, with 0.84MWh produced by the engine "exhaust" and 0.38MWh produced by the engine block. Some of the heat energy produced by the "engine block" is used to heat the Biodigester and is not available for commercial use.

5Application of biomethane as an alternative for the generation of Steam and also possible sale of commercial CO2.

Biogas, after purification, can be used as fuel gas for the generation of Steam in boilers that use Natural Gas as fuel.

In order for the biogas produced to be used in Natural Gas Boilers, it is necessary to pass the biogas through an industrial process. This process consists of:

• Extract the sulfuric gas (H2S) and the humidity (H2O) from the biogas.

• Eliminate possible undesirable gases within the biogas, such as ammonia (NH3), oxygen (O2), hydrogen (H2) and nitrogen (N2).

• The gas resulting from the steps of the above process will be a gas composed basically of methane gas (CH4) and carbon dioxide (CO2). In this step it is necessary to separate the methane gas (CH4).

The gas resulting from the steps of the previous process is biomethane (methane CH4) and will feed directly into the Boilers exclusive to Natural Gas and no adaptation is necessary.


BIOMETHAN

high calorific fuel.


Economically viable for the energy sector


High fuel power

Automobiles or cargo vehicles


  • Behavior equal to CNG
  • Diesel replacement
  • energetically independent
Dólar
5,4440
Euro
6,3907