World energy revolution. What Is Combustible Ice?
What are methane hydrates
Methane hydrates were discovered in northern Russia in the 1960s and are classified as non-conventional gases. They are a solid substance with the appearance of ice, which traps in its interior methane molecules, the major component of natural gas that we usually use.
Methane Hydrate. It is a resource composed of crystalline accumulations formed by natural gas and water, which, when found under conditions of high pressures and low temperatures, form ice-like solids. It is the cleanest fossil fuel with the environment due to its high hydrogen/carbon (H / C) ratio and increasing applicability not only as fuel but also as a chemical raw material, and the potential volume available is enormous.
Methane hydrates receive different names: gas hydrates, methane clathrate, methane ice, combustible ice, flammable ice. They have been formed from the methane originated after the anaerobic decomposition by bacterial action of the organic matter deposited in the seabed and due to the combination of high pressures and low temperatures.
Most of the reserves of methane hydrates are found in the ocean floor, at depths greater than 500 meters and at low temperatures, with a minority of the Arctic regions, under the permafrost, the permanently frozen soil layer.
Huge world reserves
Trapped under seabeds and wide expanses of permafrost, it is estimated that 160 cubic meters of gas can be extracted from a cubic meter of the compound. With the global reserves being considered, the global gas demands of 80 to 800 years could be satisfied taking into account the current consumption rates. Because the methane hydrate exceeds in quantity all the oil, coal and gas added that contains the Earth.
It is estimated that the total volume of global reserves of methane hydrates far exceeds those of conventional gas, and even to the total sum of coal, oil and gas reserves combined. They have a high energy potential, so much so that a cubic meter of combustible ice can release some 160 cubic meters of methane.
Potentially, methane hydrates are a future energy source of enormous importance, capable of replacing other sources of fossil energy. For example, only in the Nankai Trench (Japan) are sufficient reserves estimated to supply Japan's gas demand for a decade. There are large deposits under all oceans, especially on the edges of continental shelves. Being a source of energy widely distributed throughout the planet, its potential reach extends to many regions and several countries have exploration and research programs underway.
Extraction Challenges
In addition to having to reach them at the bottom of deep oceanic platforms and operate at low temperatures and extremely high pressure, there is the potentially serious risk of destabilizing the seabed, which can cause underwater landslides. Methane leaks are an even greater potential threat. The extraction of gas from a localized area does not present many difficulties, but avoiding the decomposition of hydrates and the subsequent release of methane in surrounding structures is more complicated. And the methane released has serious consequences for global warming: recent studies suggest that gas is 30 times more harmful than CO2.
The risks to the environment
According to the industry, its commercial development will not happen until 2030, although on a small scale it could happen as early as 2020. The United States and India also have a research program aimed at finding out how to extract this massive source of energy that hosts arctic permafrost and the Antarctic ice.
Methane is a greenhouse gas with a global warming potential much higher than that of CO2, therefore, the exploitation and use of methane hydrates involves serious risks. Although it is recognized that it would be a revolution, defenders of the environment remember that it should not displace work with renewable energies. The 'combustible ice' will be less dirty than coal, but it does not stop being a hydrocarbon that heats the planet.
Currently, the presence of methane in the atmosphere contributes 20% to the greenhouse effect. If there were massive exploitation of existing methane hydrate resources, we could incur an increase in the presence of CO2, due to the combustion of methane, since it is a carbon-dependent energy, and also in an increase of the presence of free methane in the atmosphere, by the punctual and diffuse emissions derived from the mining of methane hydrates.
In any case, we will have to wait to find out if we are facing a real revolution in the energy field. "The real importance of this advance will depend on the technical and economic feasibility on a commercial scale of the extraction technologies experienced and the level of commitment to the agreements signed to limit global warming.