Almost everyone has heard of methane. It is one of the most sought after and utilized hydrocarbons on the planet. Its simple molecular structure, CH4, means that, when used responsibly, it can provide more power with less pollutants than many other fuels including coal, gasoline, and diesel.
Natural Gas (another name for Methane) is used in most homes for heating and is the primary energy source for power generation in many US States(1). Since 2005, the transition in many states from coal to Natural Gas power generation has seen a reduction in CO2 emissions by 42%.
With that being said, many states have come out against the use of Natural Gas, going as far as banning future Natural gas hookups, forcing builders to install electric boilers in lieu.
When we consider the vast amount of energy consumed from methane as a fuel, it is hard to imagine where an alternative source of energy will come from in a relatively short time frame. From this perspective, it is clear that the use of Methane is not going away any time soon; however, we need to be intentional about finding ways of using the fuel source in the most efficient and responsible manner.
Before we go any further, let’s understand a little more about methane: where it comes from, how it stacks up against other energy producing solutions, and how it can be put to use in an environmentally responsible way.
Where Does Methane Come From?
There are 5 main ways that methane is generated:
| Methane Generation Type | Description | Typical Example |
| Biogenic Methane | This is methane produced by biological processes, primarily by methanogenic archaea.
Biogenic methane is the largest source of methane emissions globally. |
Typically found in environments such as wetlands, marshes, rice paddies, and the digestive systems of animals. |
| Thermogenic Methane | This type of methane is formed by the thermal breakdown of organic matter under high temperature and pressure conditions.
Thermogenic methane is the primary component of natural gas. |
Typically found in fossil fuel deposits such as coal, oil, and natural gas. |
| Abiotic Methane | Methane can also be formed through non-biological processes. Abiotic methane is generated through chemical reactions, such as the interaction of water and rocks containing hydrocarbons under high temperatures and pressures. This process is known as abiogenic methane formation. | Methane can be released during volcanic eruptions as a result of the heating and degassing of organic matter, such as buried plant material, or the decomposition of organic compounds in magma or volcanic gases |
| Methanogenesis from CO2 and H2 | Some micro-organisms known as methanogens are capable of producing methane by using carbon dioxide (CO2) and hydrogen (H2) as substrates. | This process occurs in environments with low oxygen levels, such as peatlands, sediments, and the gastrointestinal tracts of animals. |
| Anthropogenic Methane* | Human activities contribute to methane emissions through various processes. | Examples include the production and transport of coal, oil, and natural gas, as well as the management of agricultural waste and landfills. |
*Other than anthropogenic methane, all forms of methane production are naturally occurring.
When released into the environment, these naturally occurring forms of methane are considered a Greenhouse Gas (GHG) and can be 23 times more impactful toward climate change than Carbon Dioxide.
Before we explore the potential uses of methane, we need to define greenhouse gases (GHG) and why they need to be minimized.
What Are Greenhouse Gas (GHG) Pollutants?
A greenhouse gas pollutant is a gas that exists in the atmosphere that traps heat from the sun within the atmosphere and potentially contributes to the warming of our planet. Notable GHG pollutants include; carbon dioxide, methane, nitrous oxide, and fluorinated gases.
The current theories around the warming of our planet show that the temperature of the atmosphere increases as the concentration of GHGs in the atmosphere increases.
Obviously, this is something that we want to avoid so we need to do all we can to reduce or eliminate as many man-made GHG emissions as is reasonably possible.
If the first step in this process is to understand what gases are GHG pollutants (which we identified above), the second step is to establish a comparison standard or a common language so we all understand what is being measured and its potential impact.
One of the current comparison standards for GHG pollutants is to convert them to kilograms of CO2 equivalent per 1000 BTUs of energy produced (e.g., kg CO2e/1000BTU). This measurement tells us the equivalent amount of CO2 created by generating 1000BTUs of energy using the fuel in question.
The list below normalizes the GHG potential impact of various energy sources against the CO2e standard:
| Diesel car | 73 kg CO2e/1000 BTU |
| Gasoline car | 62 kg CO2e/1000 BTU |
| Vented methane | 53 kg CO2e/1000 BTU |
| Flared methane | 45 kg CO2e/1000 BTU |
| Lithium-ion battery (1MWh) | estimated between 17 to 31 kg CO2e/1000 BTU |
| Methane fueled reciprocating engines | 13 kg CO2e/1000 BTU |
| Solar PV (1MW) | 11.7 kg CO2e/1000BTU (2) |
| Wind Turbine (1MWh) | 3.2 kg CO2e/1000BTU (3) |
Although it is not surprising to see that diesel, gas, vented or flared methane have higher GHG emissions than solar or wind, it may be surprising to some to see that methane fueled reciprocating engines have significantly less GHG emissions. In fact, methane fueled reciprocating engines are similar in emissions to solar PV and are less than a 1MW lithium-ion battery.
This is because solar, wind, and battery storage systems require large amounts of material and energy in their manufacturing and installation processes. In addition to this, we must consider that most microgrids require a battery system to store electricity. This means that a 1MW solar installation must include the battery and solar GHG emissions. So, for this example, the total GHG emissions would be 17+11.7 or 28.7 kg CO2e/1000 BTU which is more than double a Methane fueled reciprocating engine.
The Importance of Methane Capture
While methane emissions are a contributor to global greenhouse gas emissions, these emissions can be significantly reduced by capturing and utilizing methane in a responsible manner. The “low-hanging” fruit for methane capture would be things like:
- Eliminating methane venting and flaring from every oil and gas facility worldwide, onshore and offshore. North American European producers generally do a good job in this area so focusing on assisting other world areas with technology support and infrastructure upgrades would provide the biggest return on investment.
- Implement biogas digesters and capture systems at all wastewater treatment facilities
- Implement biogas digesters and capture systems for agricultural and livestock waste
- Implement recovery of methane gas from all landfill sites
Capturing methane with techniques like this would go a long way to reducing methane emissions. The next step in this process is to determine how to use the methane to benefit humanity while minimizing the downside to our environment.
Reciprocating Engines
Reciprocating engines are commonly used in a variety of applications, including power generation, transportation, and industrial processes. These engines can run on a variety of fuels, including methane, propane, gasoline, and diesel.
When used with methane, reciprocating engines can provide significant environmental and economic benefits. Methane is a cleaner-burning fuel than propane, gasoline or diesel and when used in a reciprocating engine, results in lower greenhouse gas emissions and improved air quality (see list of GHG gases emitting power sources above).
These engines can produce electricity when they are coupled with an alternator and, if you add a heat recovery system to it, you can build a system that is close to 93% efficient (e.g., only loses 7% of the energy burned) while reducing emissions by over 300% compared to vented methane (e.g., allowing methane for wastewater plants to vent directly to the atmosphere).
The Future of Methane Fuel in Reciprocating Engines
While methane emissions are a contributor to global greenhouse gas emissions, they can be significantly reduced through responsible management practices and, at the same time, used to generate cost-effective and reliable electrical power.
Strong regulations and policies are necessary to ensure that methane is managed responsibly, and advancements in technology are playing an important role in methane detection and measurement. As the world continues to transition to a low-carbon economy, the responsible management of methane emissions will be an important part of the solution to address global climate change.
Summary
In conclusion, using natural gas in reciprocating engines can provide significant environmental and economic benefits, but it requires responsible management practices, including methane capture. Methane capture allows methane emissions to be reduced and utilized as a fuel source, resulting in a significant reduction in greenhouse gas emissions. Advancements in technology are playing an important role in methane detection and measurement, and as the world continues to transition to a low-carbon economy, the responsible management of methane.
If you have any questions around this article or if you have a methane source that you would like to use to create electricity, give us a call at Collicutt at 888.682.6888.
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