Hemp is efficient at turning sunlight into biomass. It can produce up to four times more fiber per acre than trees. It's a very durable fiber and industrially useful fiber. It's outlaw status in the US is a shame because it forces the use of much less environmentally friendly alternatives for fiber and biofuel. Industrial hemp contains less than 1% THC, the psychoactive ingredient in marijuana. Hemp grown for drug use, contains more than 10% THC. Industrial hemp would not be sought for recreational drug use. Anyone who has ever tried to smoke marijuana of this quality would understand. The closest you would get to a high is a headache from carbon monoxide. Unfortunately, there is nothing rational about federal drug laws. Hemp grown for biomass could fuel a trillion-dollar-per-year energy industry, while improving air quality and distributing the wealth to rural areas and their surrounding communities, and away from centralized power monopolies. More than any other plant on Earth, hemp holds the promise of a sustainable ecology and economy.
1. Introduction
Hemp had been grown as a major product in America since colonial times by such men as George Washington and Thomas Jefferson and has had both governmental and popular support. Hemp´s long history in civilization and the multitude of products that can be derived from this single plant has made it one of the most valuable and sustainable plants in the history of mankind. More importantly to the biofuel industry, hemp provided the biomass that Ford needed for his production of ethanol. He found that 30% hemp seed oil is usable as a high-grade diesel fuel and that it could also be used as a machine lubricant and an engine oil.
Biodiesel (methyl esters) is an ASTM certified diesel fuel replacement. It is highly efficient and comprised of vegetable oils like soy, recycled restaurant oils or fats. Unlike traditional diesel, it contains no sulfur and has a higher flash point than diesel. Using hempoline does not require mechanical modifications of any kind, all one needs is a diesel-powered vehicle. Hempoline is also carbon neutral, meaning it will not increase greenhouse gas emissions. Also hempoline is one way to provide direct aid to America’s farmers. The Ford F-250, owned by the president of Vogelbilt, is now one year old with 50,000 miles of driving only using Biodiesel in the tank. There are many reasons to stop using petroleum-based energy products and convert to alternative fuels. Prevalent among these are health and safety. The Lovelace Respiratory Institute has confirmed that Biodiesel has: no pronounced toxicity at any level, no mortality/ clinical abnormality, no neurological/internal pathologic response, and no adverse effect on fertility/reproductive systems. The market for energy is rapidly changing and renewable energy is the way to ensure, healthy tomorrows.
COMPARISON OF BIODIESEL AND DIESEL SPECIFICATIONS
ASTM D 975 specifies acceptable properties of diesel. The biodiesel samples produced for this project met most of the specifications. Their Flash Points were at least 76°C (137°F) above the minimum. Ash for the samples were half or less of the maximum acceptable value, except for the yellow grease biodiesels (which may have been due to processing and could be corrected now that it is known). The Ramsbottom Carbon Residue maximum of 0.35% was met by the biodiesels, and all but one met the biodiesel specification of 0.05%. The biodiesels all met the requirement of a Cetane number of 40 by at least 7. Sulfur levels in biodiesel were below detectable limits for the test method specified by D 975.
However, the hempoline have problems meeting D 975 requirements in three areas. For the biodiesels, the 90% distillation fraction was at or above the maximum temperature specified by D 975. The viscosity of all the biodiesels was above the maximum value of 4.1 centiStokes. Cloud Point is a problem for all of the biodiesels because the temperatures are significantly higher than the tenth-percentile ambient temperature specified by D 975. Because each of these is related to the composition of the biodiesels, D 975 may need to be changed to reflect this.
Table compares the hempoline specifications with those of D 975. The applicability of these specifications for B20 (20% biodiesel / 80% diesel) can be considered.
Comparison of Hempoline Specifications and ASTM D 975 Specifications
Residual biomass includes: rice husk, sugarcane bagasse, cane trash, cassava, coconut shells (Fig. 1), maize, wood, bio-rubbish of the cities, agricultural residues etc.. However, studies have shown that these residues could be combusted/gasified to produce heat, electricity or combined heat and power (CHP) or processed into liquid fuels (Jekayinfa and Omisakin, 2005; Soltes, 1983; Barnard and Kristoferson, 1983; Enweremadu et al., 2004). Especially in Vietnam, these biomasses are resources that can be used for generation of electricity. The bagasse potential generated from existing mills is estimated to support 100 MWth per year (MWth- thermal power in MW) of cogeneration capacity. Especially, the technical potential of rice husk is estimated at 450 MWth per year. But the two-thirds of biomass are used for animal feed or cooking. The available potential is estimated to be around one-third to one-half of the theoretic potential and placed at around 150-200 MWth per year (IET, 2004). Beside sugar cane, other biomass sources are absolutely not exploited to generate power (Nguyen, 2006, and Pham, 2005).
The Properties of Experimental Materials.
The experimental fuel here is Hemp residues. This fuel has similar properties as some biomass in Asia. The chemical properties and NCV of this fuel will be analysed to clear the chemical components. The analyse results of the material above is compared with the biomass of Asia in Table 3 and Fig. 2. The comparison shows that the fuel properties of biomasses are basically the same. Rice husks attract attentions because of its high ash content. All values are produced in own analyses.
It has nearly the same properties such density, according to ISO net calorific value (NCV) of fuel etc. particularly the physical, chemical properties like components of carbon (C), oxygen (O), hydro (H), nitrogen (N), sulphur (S), ash (a), water (w) as rice husk, bagasse, coconut shells, cassava residues in Vietnam. But ash compositions can be different. In Table 3 these properties are presented and their characteristics with biomass in Vietnam can be compared.
Comparison of NCV, chemical compositions of biomasses (w, fuel-moisture; a, fuel-ash)
If no sulphur is in fuels the chlorine emission can be limited by feeding Ca-additives, e.g. CaO or
CaCO3.
A comparison between the chemical compositions of different fuels
Performance and Emissions Characteristics
One of themost important characteristics of diesel fuel is
its ability to autoignite, a characteristic that is quantified by a fuel’s cetane number or cetane index, where a higher cetane number or index means that the fuel ignites more quickly. U.S. petroleum diesel typically has a cetane index in the low 40s, and European diesel typically has a cetane index in the low 50s. Graboski and McCormick8 have summarized several experimental studies of biodiesel characteristics. They report that the cetane number for biodiesel ranges from 45.8 to 56.9 for soybean oil methyl esters, with an average of 50.9. In comparison the cetane index for petroleum diesel ranges from40 to 52. They imply that careful production control could result in biodiesel products with cetane numbers in the high end of the range, whereas petroleum diesel tends toward the low end of the range. U.S. refiners use the catalytic cracking and coking processes to increase gasoline output from oil refineries, yielding high-octane gasoline material but low-cetane diesel material.
Lubricity, another important characteristic of diesel fuel,
is ameasure of lubricating properties. Fuel injectors and
some types of fuel pumps rely on fuel for lubrication.
One study, published in 1998 and cited by the National
Biodiesel Board, found that one-half of samples of petro-
leum diesel sold in the United States did not meet the
recommended minimum standard for lubricity. Bio-
diesel has better lubricity than current low-sulfur petro-
leum diesel, which contains 500 parts per million (ppm)
sulfur by weight. The petroleum diesel lubricity problem is expected to get worse when ultra-low-sulfur petroleum diesel (15 ppm sulfur by weight) is introduced in 2006. A 1- or 2-percent volumetric blend of biodiesel in low-sulfur petroleum diesel improves lubricity substantially.
10 It should be noted, however, that the use of other lubricity additives may achieve the same effect at lower cost.
Biodiesel also has some performance disadvantages.
The performance of biodiesel in cold conditions is markedly worse than that of petroleum diesel, and biodiesel made from yellow grease is worse than soybean bio diesel in this regard. At low temperatures, diesel fuel forms wax crystals, which can clog fuel lines and filters in a vehicle’s fuel system. The “cloud point” is the temperature at which a sample of the fuel starts to appear cloudy, indicating that wax crystals have begun to form.
At even lower temperatures, diesel fuel becomes a gel that cannot be pumped. The “pour point” is the temperature below which the fuel will not flow. The cloud and pour points for biodiesel are higher than those for petroleum diesel.
Vehicles running on biodiesel blends may therefore exhibit more drivability problems at less severe winter temperatures than do vehicles running on petroleum diesel. This is a potential concern during the winter in much of the United States. The solvent property of biodiesel can cause other fuel-system problems. Bio-
diesel may be incompatible with the seals used in the
fuel systems of older vehicles and machinery, necessitating the replacement of those parts if biodiesel blends are
used.
The initial use of B20 or B100 in any vehicle or machine requires care. Petroleum diesel forms deposits in vehicular fuel systems, and because biodiesel can loosen those deposits, they can migrate and clog fuel lines and filters.
Another disadvantage of biodiesel is that it tends to reduce fuel economy. Energy efficiency is the percentage of the fuel’s thermal energy that is delivered as engine output, and biodiesel has shown no significant effect on the energy efficiency of any test engine. Volumetric efficiency, a measure that is more familiar to most vehicle users, usually is expressed as miles traveled per gallon of fuel (or kilometers per liter of fuel). The energy
content per gallon of biodiesel is approximately 11 percent lower than that of petroleum diesel. Vehicles running on B20 are therefore expected to achieve 2.2 percent (20 percent x 11 percent) fewer miles per gallon of fuel.
About 11 percent of the weight of B100 is oxygen. The presence of oxygen in biodiesel improves combustion and therefore reduces hydrocarbon, carbon monoxide, and particulate emissions; but oxygenated fuels also tend to increase nitrogen oxide emissions. Engine tests have confirmed the expected increases and decreases of each exhaust component from engines without emissions controls. Biodiesel users also note that the exhaust smells better than the exhaust from engines burning conventional diesel.
The increase in nitrogen oxide emissions from biodiesel is of enough concern that the National Renewable Energy Laboratory (NREL) has sponsored research to find biodiesel formulations that do not increase nitrogen oxide emissions. Adding cetane enhancers—di-tert-butyl peroxide at 1 percent or 2-ethylhexyl nitrate at 0.5 percent—can reduce nitrogen oxide emissions from biodiesel, and reducing the aromatic content of petroleum diesel from31.9 percent to 25.8 percent is estimated to have the same effect. In the case of petroleum diesel, the reduction in aromatic content can be accomplished by blending fuel that meets U.S. Environmental Protection Agency (EPA) specifications with fuel that meets California Air Resource Board (CARB) specifications. EPA diesel contains about 30 percent aromatics, and CARB diesel is limited to 10 percent aromatics.
Nitrogen oxide emissions from biodiesel blends could possibly be reduced by blending with kerosene or Fischer-Tropsch diesel. 16 Kerosene blended with 40 percent biodiesel has estimated emissions of nitrogen oxide no higher than those of petroleum diesel, as does Fischer-Tropsch diesel blended with as much as 54 percent biodiesel. These results imply that Fischer- Tropsch diesel or kerosene could be used to reduce nitrogen oxide emissions fromblends containing 20 percent biodiesel, although the researchers did not investigate those possibilities. Blending di-tert-butyl peroxide into B20 at 1 percent is estimated to cost 17 cents per gallon (2002 cents), and blending 2-ethylhexyl nitrate at 0.5 percent is estimated to cost 5 cents per gallon.
Oxides of nitrogen and hydrocarbons are ozone precursors. Carbonmonoxide is also an ozone precursor, but to a lesser extent than unburned hydrocarbons or nitrogen oxides. Air quality modeling is needed to determine whether the use of biodiesel without additives to prevent inreases in nitrogen oxide emissions will increase or decrease ground-level ozone on balance. Most biodiesel emission studies have been carried out on existing heavy-duty highway engines. The effects of biodiesel on emissions from heavy diesel engines meeting EPA’s stringent Tier II emissions standards (slated for introduction in model year 2007) have not been determined, and the EPA has concluded that the results of biodiesel tests in heavy-duty vehicles cannot be generalized to light-duty diesel vehicles or off-highway diesel engines.
Biodiesel from virgin vegetable oil reduces carbon dioxide emissions and petroleum consumption when used in place of petroleum diesel. This conclusion is based on a life cycle analysis of biodiesel and petroleum diesel, accounting for resource consumption and emissions for all steps in the production and use of the fuel. NREL estimates that the use of soybean B100 in urban transit buses reduces net carbon dioxide emissions by 78.45 percent.
The comparison of carbon dioxide emissions and energy use begins with soybean cultivation and petroleum extraction, proceeds with all applicable processing and transportation, and ends with combustion in the bus engine. The growth of the soybean plant is assumed to absorb as much carbon dioxide as is emitted by decomposition of crop residue after the harvest and by combustion of biodiesel in the engine.
Petroleum-based chemicals and fuels are used to produce the soybeans, but soybean oil biodiesel contains energy from other sources, including solar energy. NREL estimates that B100 reduces life cycle petroleum consumption by 95 percent relative to petroleum diesel, 22 assuming that the quantity of biodiesel is small enough not to affect production levels of soybeans or other crops. If crop production patterns changed significantly, then NREL's analysis might not be valid.
Conclusion
The results of this study show that biodiesel production from hemp is a promising possibility for production of vehicle fuel from energy crops. The harvest of year 2006 showed a high biomass yield for hemp, more than 14 tons TS per hectare, and if other harvest determinations will confirm this, hemp will be one of the highest yielding crops in Sweden, if not the highest. Already with the simple batch digestion used in the present study, the biodiesel yield from hemp gave one of the highest gross yields of vehicle fuel per hectare achieved in Sweden. Still, there is a large potential to improve the methane yield. The harvest time showed to have little effect on the specific methane yield but a large effect on the biomass yield and thus the methane yield per hectare. The best methane yield per hectare was achieved when harvesting in September through October. Caution should be taken if digesting hemp harvested early (July), and possibly also for later harvested hemp, because of the risk of inhibition of the process.
