Thus, it is not surprising that the abundant resources of oil shale in the United States were given consideration as a major source for these fuels. In fact, the Mineral Leasing Act of 1920 made crude oil and oil shale resources on federal lands available for development under the terms of federal mineral leases. This enthusiasm for oil shale resources was mitigated to a large extent by the discoveries of more economically producible and easy-to-refine liquid crude oil in commercial quantities, which caused the interest in oil shale to decline markedly.
However, the interest in oil shale resumed after World War II, when military fuel demand and domestic fuel rationing and rising fuel prices made the economic and strategic importance of the oil shale resource more apparent. After the war, the booming postwar economy drove demand for fuels ever higher, starting with the commencement of the development, in 1946, of the Anvil Point, Colorado, oil shale demonstration project by the United States Bureau of Mines. Significant investments were made by commercial companies to define and develop the US oil shale resource and to develop commercially viable technologies and processes to mine, produce, retort, and upgrade oil shale into viable refinery feedstocks and by-products. Once again, however, major crude oil discoveries in the lower-48 United States, off-shore, and in Alaska, as well as other parts of the world, reduced the foreseeable need for shale oil and interest and associated activities again diminished.
By 1970, oil discoveries were slowing, demand was rising, and crude oil imports into the United States, largely from the Middle Eastern oil-producing nations, were rising to meet demand. Global oil prices, while still relatively low, were also rising, reflecting the changing market conditions. Ongoing oil shale research and testing projects were reenergized and new projects were envisioned by numerous energy companies seeking alternative fuel feedstocks (Speight, 2008, 2011c). These efforts were significantly amplified by the impact of the 1973 Arab oil embargo which demonstrated the vulnerability of the oil-consuming nations, particularly the United States, to oil import supply disruptions, and were underscored by a new supply disruption associated with the 1979 Iranian Revolution.
By 1982, however, technology advances and new discoveries of offshore oil resources in the North Sea and other bodies of water provided new sources for oil imports into the United States. Thus, despite significant investments by energy companies, numerous variations and advances in mining, restoration, retorting, and in-situ processes, the costs of oil shale production relative to current and foreseeable oil prices, made continuation of most commercial efforts impractical.
Despite the huge resources, oil shale is an underutilized energy resource. In fact, one of the issues that arise when dealing with fuels from oil shale is the start-stop-start episodic nature of the various projects. The projects have varied in time and economic investment and viability. The reasons comprise competition from cheaper energy sources, heavy front-end investments and, of late, an unfavorable environmental record. Oil shale has, though, a definite potential for meeting energy demand in an environmentally acceptable manner (Bartis et al., 2005; Andrews, 2006; Speight, 2020).
1.3.3 Biomass
Biomass is a renewable resource that has received considerable attention due to environmental considerations and the increasing demands of energy worldwide (Brown, 2003; NREL 2003; Wright et al., 2006; Tsai et al., 2007; Speight, 2008; Langeveld et al., 2010; Speight, 2011c; Lee and Shah, 2013; Hornung, 2014). Biomass is produced by a photosynthetic process (photosynthesis) which involves chemical reactions occurring on the Earth between sunlight and green plants within the plants in the form of chemical energy. In the process, solar energy is absorbed by green plants and some microorganisms to synthesize organic compounds from low-energy carbon dioxide (CO2) and water (H2O). For example,
The general formula of the organic material produced during photosynthesis process is (CH2O)n which is mainly carbohydrate material. Some of the simple carbohydrates involved in this process are the simple carbohydrates glucose (C6H12O6) and sucrose (C12H22O11) and constitute biomass, which is a renewable energy source due to its natural and repeated occurrence in the environment in the presence of sunlight. The amount of biomass that can be grown certainly depends on the availability of sunlight to drive the conversion of carbon dioxide and water into carbohydrates. In addition to limitations of sunlight, there is a limit placed by the availability of appropriate land, temperature, climate and nutrients, namely nitrogen, phosphorus and trace minerals in the soil.
Biomass is clean for it has negligible content of sulfur, nitrogen and ash, which give lower emissions of sulfur dioxide, nitrogen oxides and soot than conventional fossil fuels. Biomass resources are many and varied, including (i) forest and mill residues, (ii) agricultural crops and waste, (iii) wood and wood waste, (iv) animal waste/s, (v) livestock operation residues, (vi) aquatic plants, (vii) fast-growing trees and plants, (viii) municipal waste, and (ix) and industrial waste. The role of wood and forestry residues in terms of energy production is as old as fire itself and in many societies wood is still the major source of energy. In general, biomass can include anything that is not a fossil fuel that is based on bio-organic materials other than natural gas, crude oil, heavy crude oil, extra heavy crude oil and tar sand bitumen (Lucia et al., 2006; Speight, 2008, 2011c; Lee and Shah, 2013).
There are many types of biomass resources that can be used and replaced without irreversibly depleting reserves and the use of biomass will continue to grow in importance as replacements for fossil fuel sources and as feedstocks for a range of products (Narayan, 2007; Speight, 2008, 2011c; Lee and Shah, 2013). Some biomass materials also have particular unique and beneficial properties which can be exploited in a range of products including pharmaceuticals and certain lubricants. In this context, the increased use of biofuels should be viewed as one of a range of possible measures for achieving self-sufficiency in energy, rather than a panacea to completely replace the fossil fuels (Crocker and Crofcheck, 2006; Worldwatch Institute, 2006; Freeman, 2007; Nersesian, 2007).
Worldwide biofuels production is still small at approximately 70 billion (70 x 109 tons) oil equivalent. With the volatility of crude oil prices of crude oil, the relative competitiveness of renewable and alternative fuels is drastically improving. Further, technological advances in the alternative renewable energy areas as well as public awareness backed by strong governmental supports and incentives, make the outlook of the alternative and renewable energy very promising (Energy Security Leadership Council, 2013). There are seven countries that can be considered the leaders in biofuels (particularly bioethanol) production. The leaders are (as a percentage of the total production): United States (43.5%), Brazil (24%), France (3%), Germany (4%), Argentina (3%), China (3%), and Indonesia (2.5%). But this still represents minor amounts of the total energy consumption in these countries.
Ethanol (bio-ethanol) from corn has been used in an accelerated pace as gasoline blending fuel as well as a new brand of fuel E85, which contains 85% ethanol and 15% gasoline. The majority of the gas stations in the United States supply E85 fuels regularly and many automakers are offering multiple lines of automobiles that can be operated on either conventional gasoline or E85. This not only contributes to cleaner burning fuels but also supplements the amount of gasoline sold.
One extremely important aspect of biomass use as a process feedstock is the preparation of the biomass (also referred to as biomass cleaning or biomass pretreatment), the removal of any contaminants that could have an adverse effect of the process and on the yields and quality of the products. Thus, feedstock preparation is, essentially, the pretreatment of the biomass feedstock to assist in the efficiency of the conversion process. In fact, pretreatment of biomass is considered one of the most important steps in the overall processing in a biomass-to-biofuel program and can occur using acidic or alkaline reagents (Table 1.3) as well as using a variety of physical methods (Table 1.4) and the method of choice depends very much upon the process needs. With the strong advancement in developing lignocellu-lose
