HYDROGEN STORAGE AND TRANSPORTATION

                                                                   Methane

Methane is a powerful greenhouse gas emitted by human activities such as leakage from natural gas systems and the raising of livestock, as well as by natural sources such as wetlands. Methane is a short-lived climate pollutant with an atmospheric lifetime of around 12 years. While its lifetime in the atmosphere is much shorter than carbon dioxide (CO₂), it is much more efficient at trapping radiation. Per unit of mass, the impact of methane on climate change over 20 years is 84 times greater than CO₂; over a 100-year period, it is 28 times greater.

As the major constituent of natural gas, methane is important for electricity generation by burning it as a fuel in a gas turbine or steam generator. Compared to other hydrocarbon fuels, methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion is lower than that of any other hydrocarbon. However, it produces more heat per mass (55.7 kJ/g) than any other organic molecule due to its relatively large content of hydrogen, which accounts for 55% of the heat of combustion but contributes only 25% of the molecular mass of methane. In many cities, methane is piped into homes for domestic heating and cooking. In this context, it is usually known as natural gas, which is considered to have an energy content of 39 megajoules per cubic meter or 1,000 BTU per standard cubic foot. Liquefied natural gas (LNG) is predominantly methane (CH₄) converted into liquid form for ease of storage or transport.

Sources of Methane   

          

Agricultural emissions come primarily from livestock such as cattle and sheep, which burp methane as a result of how they digest their food. 

In the fossil fuel sector, methane is released by coal mining and leaks from oil and gas wells, pipelines as well as gas stoves in peoples’ homes.

The increases in emissions were sharpest in Africa and the Middle East; China; and South Asia and Oceania, which had each added 10 to 15 million tons of methane emissions per year by 2017, according to the report. China’s increasing methane emissions were largely due to an uptick in coal use, per the Times, while agriculture drove the rise in South Asia and Oceania as well as, to a lesser extent, Africa, according to Science News.

other sources include the release of methane from seas and soils in permafrost regions of the Arctic.

Arctic methane concentrations up to October 2019. A monthly peak of 2000 ppb was reached in October 2019

Loss of Permafrost

The water trapped in the soil doesn't freeze completely even below 32 degrees Fahrenheit (0 degrees Celsius). The top layer of the ground, known as the active layer, thaws in the summer and refreezes in the winter, and it experiences a kind of sandwiching effect as it freezes. When temperatures are right around 32 degrees Fahrenheit – the so-called "zero curtain" – the top and bottom of the active layer begin to freeze, while the middle remains insulated. Microorganisms in this unfrozen middle layer continue to break down organic matter and emit methane many months into the Arctic's cold period each year.

clathrate breakdown

Sea ice, and the cold conditions it sustains, serves to stabilize methane deposits on and near the shoreline, preventing the clathrate breaking down and outgassing methane into the atmosphere, causing further warming. Melting of this ice may release large quantities of methane, a powerful greenhouse gas into the atmosphere, causing further warming in a strong positive feedback cycle

METHANE IMPACTS

CLIMATE IMPACTS

Methane is generally considered second to carbon dioxide in its importance to climate change. The presence of methane in the atmosphere can also affect the abundance of other greenhouse gases, such as tropospheric ozone, water vapor and carbon dioxide.

Recent research suggests that the contribution of methane emissions to global warming is 25% higher than previous estimates.

HEALTH IMPACTS

Methane is a key precursor gas of the harmful air pollutant, tropospheric ozone. Globally, increased methane emissions are responsible for half of the observed rise in tropospheric ozone levels.

While methane does not cause direct harm to human health or crop production, ozone is responsible for about 1 million premature respiratory deaths globally.