Hydrothermal liquefaction is a process that converts biomass materials, in the presence of water, into bio-liquid products with high energy content at a temperature of between 280-370°C .and high pressure of between 10 to 25MPa. Water acquires unique characteristics under these conditions that facilitates hydrolysis, depolymerisation and biomass decomposition to produce a water-insoluble bio-oil (Tungal, 125). Hydrothermal liquefaction is a very robust process such that it accepts various forms of biomass materials including wood, algae and biomass waste like municipal waste, industrial manure or by-products. Sample drying is the best course for the problem. Solar drying is mostly used but takes a takes longer for the moisture content to be lowered.
The process also produces other gaseous, aqueous and solid phase by-products. The mechanism of the process is classified according to two types of feedstock, that is wet feedstock (algal biomass) and dry feedstock (lignocellulose) the sub-classification of the dry biomass is hemicellulose, lignin, and cellulose. The subclassification of wet stock is proteins carbohydrates, lipids, and algae nans. Therefore, HTL is the best method because it gives high energy efficiency whereby water is used as a solvent as well as a catalyst for organic compounds degradation. This process helps in the reduction of global warming.
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"Hydrothermal Liquefaction Processes Vs. Petroleum Refining Processes".
On the other hand, petroleum refining is a process where crude oil is separated into hydrocarbon groups through distillation or fractionation. The resulting products are related to the crude oil characteristics being processed. Some of the products are mostly converted into more usable products by changing their molecular and physical structures through reframing cracking and other processes of conversion (The Three Stages of Refining). Subsequently, the products are subjected to different separation and treatment processes such as hydrotreating, extraction and sweetening to produce the final products. Simple refineries mostly are limited to vacuum and atmospheric distillation whereas integrated refineries primarily incorporate conversion, fractionation, and treatment and blending with lubricants, asphalt manufacturing, and heavy fuels (Dedini 70). They may also integrate petrochemical processing. This process largely contributes to global warming.
How the HTL Reduce the emissions of Green House Gases?
Molecules of gas that are in significant quantity and can absorb thermal infrared radiations can cause climate change. These gases molecules are known as greenhouse gases. These gas molecules act as a blanket, whereby it absorbs the infrared emissions and prevent it from escaping into the outer space. This gradually leads to the earth’s surface, and the atmosphere is heating, a process called global warming. Examples of this kind of gases include nitrous oxide (N2O), CO2 methane and water vapour.
During the HTL process, the hydrogen donors are used for stabilisation of fragmented products of liquefaction. Generally, these gases inhibit cyclization, condensation, and re-polymerisation of free radicals. Although hydrogen is the most effective stabilising agent, it is expensive. Various gases like nitrogen gas, steam, synthesis gas, and argon are used as stabilising agents. Air cannot be used as a reducing agent since it leads to the combustion of the biomass. Reactive gases are generally better when compared to inert gases during the HTL process. Hydrogen gas and synthesis gas are the most recommended reducing gases. Most of the gases used as a reducing agent are made of elements of carbon, nitrogen, hydrogen, and steam. These are the same elements that make up the greenhouse gases. Therefore the HTL process reduces the emission of greenhouse gases by utilising their components. Steam, a greenhouse gas is also used during the HTL process.
How Oil refiners and Petroleum refining processes affect the Atmosphere
Gaseous emissions occur from the petroleum industry in every stage of the production process from extraction to consumption. During mining, pollutants such as carbon dioxide, nitrous oxide, and aerosols are emitted. During the burning of oil or petroleum distillates, combustion is not complete. The chemical reaction during this combustion leaves pollutant by-products. A large amount of pollution that occur in urban centres are caused by pollution from petroleum during the refinement stages. Combustion of petroleum also leads to an increase in the amount of carbon dioxide and other greenhouse gases (Colligan 89). The combustion of oil has led to the production of other by-products such as nitrates and carbon monoxide. The reaction of these by-products with the atmosphere produces the ozone and other greenhouse gases. The increased presence of these gases makes the atmosphere to act as a blanket, therefore, leading to increased heat (Gunderson). With high concentrations of carbon dioxide, the atmosphere traps more longwave radiation resulting in higher surface temperatures.
Effects of human activities on the atmospheres and global warming
Greenhouse gases absorb the thermal infrared radiations, therefore, acting like a blanket preventing the emissions from escaping. Greenhouse gases lead to global warming. People release greenhouse gases to the atmosphere by burning petroleum products. Deforestation also increases the levels of greenhouse gases. This is because plants reduce the levels of carbon dioxide by using it for photosynthesis. Since the industrial revolution began, the levels of carbon dioxide in the atmosphere has risen significantly (Colligan 89). The increasing concentrations of greenhouse gases combined with the greenhouse effect and global warming is expected to have drastic implications. At this rate, there will be a significant change in climate causing sea levels to rise, extreme weather events, and an increase in sea acidification among other extreme natural impacts (Gunderson). People should stop emitting greenhouse gases to the atmosphere. Emitting these gases to the atmosphere shows the level of ignorance possessed by these perpetrators. There should be a policy that limits these human activities to save the planet.
- Colligan, L. H. Global Warming. Marshall Cavendish Benchmark, 2012.
- Dedini, Michael. Petroleum Refining Processes. Syrawood Publishing House, 2016.
Evaluation of Hydrothermal Liquefaction of – m-Hikari.com. www.m-hikari.com/ces/ces2018/ces25-28-2018/p/gonzalezdCES25-28-2018-2.pdf. - Gunderson, Jessica. Global Warming. Creative Education, 2011. “Global Warming: News, Facts, Causes & Effects.” LiveScience, Purch, www.livescience.com/topics/global-warming.
- “OIL & PETROLEUM REFINING PROCESS.” Petroleum Refinery Equipment For Sale,Petroleum Product,Petroleum Machinery, 3 Dec. 2018, www.kineticpetro.com/oil-petroleum-refining-process/.
- “The Three Stages of Refining.” Planète Énergies, www.planete-energies.com/en/medias/close/three-stages-refining.
- Tungal, Richa. Catalytic Hydrothermal Processing of Biomass for Hydrogen and Biocrude Generation. 2013.
