Fossil fuels, natural gas oil

Today Production of -65 M tonnes hydrogen [mainly from fossil fuels (natural gas, oil, coal...)] at a cost of EUR 1.8/kg [USD 2.3/kg] essentially for fertilisers and refinery of heavy crude oil. 

Presently, hydrogen is mostly being produced from fossil fuels (natural gas, oil, and coal). Hydrogen is used in refineries to upgrade crude oil (hydro treating and hydro cracking), in the chemical industry to synthesize various chemical compounds (such as ammonia, methanol), and in metallurgical processes (as a reduction or protection gas). 

The main advantage of natural gas is that it burns cleanly, producing only carbon dioxide and water. Of all the fossil fuels, natural gas is considered the cleanest form of energy. It emits less sulfur, carbon, and nitrogen when burned than coal or oil and it leaves almost no solid ash particles. 

We see that the incomplete combustion of hydrocarbons yields undesirable products —carbon monoxide and elemental carbon (soot), which pollute the air. Unfortunately, all fossil fuels—natural gas, coal, gasoline, kerosene, oil, and so on—also have undesirable nonhydrocarbon impurities that burn to produce oxides that act as additional air pollutants. At this time it is not economically feasible to remove all of these impurities from the fuels before burning them. 

The pathways involving fossil fuels (natural gas, refinery oil and coal) that provide for almost 96% of the total production of hydrogen, release carbon dioxide in the atmosphere. 

The primary source of CO2 is the burning of fossil fuels - specifically gas, oil, and coal - so stabilization of atmospheric CO2 concentration will clearly require substantial reductions in CO2 emissions from these sources. For example, one commonly discussed scenario to stabilize at 500 ppm by the mid-twenty-first century suggests that about 640 Gt CO2 (c. 175 GtC) would need to be avoided over 50 years, with further emission reductions beyond 50 years. As references, a 1000 MW pulverized coal plant produces 6-8MtC02 c. 2MtC) per year, while an oil-fired single-cycle plant produces about two-thirds this amount and a natural gas combined cycle plant produces about half this amount. Thus the above scenario would require that the atmospheric emissions from the equivalent of 2000-4000 large power plants be avoided by approximately the year 2050. 

For the next few decades, saving of uranium resources by nuclear fuel breeding will not be of primary importance for countries with a significant nuclear power sector. This is caused by a number of factors, namely (a) accumulation of plutonium as a result of reprocessing of spent fuel of the operating NPPs (b) release of considerable amount of plutonium and enriched uranium owing to disarmament (c) decrease of uranium consumption in the military industry (d) slowing down of the rate of nuclear power development and (e) ready availability of fossil fuels (natural gas and oil). 

Fossil fuels—natural gas, petroleum, and coal—are the principal sources of hydrocarbons. Natural gas is primarily methane with small amounts of ethane, propane, and butane. Petroleum is a mixture of hydrocarbons from which gasoline, kerosene, fuel oil, lubricating oil, paraffin wax, and petrolatum (themselves mixtures of hydrocarbons) are separated. Coal tar, a volatile by-product of the steel industry s process of making coke from coal, is the source of many valuable chemicals, including the aromatic hydrocarbons benzene, toluene, and naphthalene. 

The LCA process takes into account all of the energy, raw materials, water, and fossil fuels required in the production of PET pellets. The first step is the extraction of crude oil. The process requires electricity, fossil fuels, natural gas, water, and other materials. The second step is the production of naptha with the use of fossil fuels, electricity, water, and other materials. The third step is the production of benzene and ethylene oxide with the use of electricity, fossil fuels, water, and other materials. The fourth step is the production of ethylene glycol and terephthalic acid with the use of fossil fuels, electricity, water, and other materials. The last step is the polymerization of PET and conversion into PET pellets with the use of electricity, fossil fuels, water, and other materials. 

In spite of advances in coal-fired power plants design and operation worldwide, they are stUl considered as not environmental friendly due to producing a lot of carbon dioxide emissions as a result of the combustion process plus ash, slag, and even acid rains. However, it should be admitted that known resources of coal worldwide are the largest compared to those of other fossil fuels (natural gas and oil). 

Atmospheric particulate emissions can be reduced by choosing cleaner fuels. Natural gas used as fuel emits negligible amounts of particulate matter. Oil-based processes also emit significantly fewer particulates than coal-fired combustion processes. Low-ash fossil fuels contain less noncombustible, ash-forming mineral matter and thus generate lower levels of particulate emissions. Lighter distillate oil-based combustion results in lower levels of particulate emissions than heavier residual oils. However, the choice of fuel is usually influenced by economic as well as environmental considerations. 

A further positive economic impact, besides increased investment, is the change of imports of fossil fuels. For crude oil, this amounts to a value of 12 billion of savings in the year 2030, with a minor compensation of increased imports of natural gas reaching more than one billion in 2030 (see Fig. 18.15). 

The crust is the largest carbon reservoir in the crustal-ocean-atmosphere factory (8 x 10 Pg C including the sediments). Most of this carbon is in the form of inorganic minerals, predominantly limestone, with the rest being organic matter, predominantly contained in shale and secondarily in fossil fuel deposits (coal, oil, and natural gas). The oceanic reservoir (4 X lO" Pg C) and the terrestrial reservoir (2 to 3 x 10 Pg C) are both far smaller than the crustal reservoir. The smallest reservoir is found in the atmospheric, primarily as CO2 (preindustrial 6 x 10 Pg C, now 8 x 10 Pg C and rising). The flux estimates in Figure 25.1 have been constrained by an assumption that the preindustrial atmospheric and oceanic reservoirs were in steady state over intermediate time scales (millennia). 

About 96% of the worlds hydrogen is currently produced from natural gas, oil or coal (48% from natural gas, 30% from oil- most of which is consumed in refineries, 18% from coal, and the remaining 4% via water electrolysis). In general the purity of hydrogen from fossil fuels is about 98% although purity in excess of 99.99% can be... 

Fossil fuels, such as oil, coal and natural gas, all contain some sulfur. When these fuels are burned they produce many different gases. Concern has grown in recent years about the effects of one of these gases, sulfur dioxide. When sulfur dioxide dissolves in rainwater it forms an acidic solution which has become known as acid rain. 

A wood pellet is a small, hard piece of bioenergy. Normally pellets have a cylindrical form, 6-8 mm in diameter and of varying length. In the last decade, softwood pellets have emerged as a renewable energy resource that can be considered as a potential future substitute, in many aspects, for fossil fuels such as oil and natural gas. The energy value of 1 ton of pellets is about 5.0 MWh, which is equal to 0.5 m3 oil. 

Hydrogen can be produced from most fossil fuels (e.g. coal, natural gas, oil, etc.). The complexity of the processes varies. Since carbon dioxide is produced as a byproduct, C02 should be captured and stored to ensure a sustainable (zero-emission) process. The feasibility and viability of the processes will vary with respect to a centralised or distributed hydrogen production plant. 

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