Which is the preferable transport fuel on a greenhouse gas basis; biomethane or ethanol?

Biomethane and ethanol are both biofuels which are generated from agricultural crops that can be utilised to meet the Biofuels Directive. In Ireland with the demise of the sugar industry 48,000 Ha of land is readily available for biofuel production, without unduly effecting food production. Which biofuel should dominate? This paper investigates biofuel production for three different crop rotations: wheat, barley and sugar beet; wheat, wheat and sugar beet; wheat only. A greenhouse gas balance is performed to determine under what conditions each biofuel is preferable. For both biofuels, the preferred crop on a weight basis is wheat, while on an area basis the preferred crop is sugar beet. Biomethane scenarios produce more gross energy than ethanol scenarios. Under the base assumption (7.41% biogas losses, and biomethane utilised in a converted petrol engine, such as a bi-fuel car, and thus underperforming on a km/MJ basis) ethanol generated more net greenhouse gas savings than biomethane. This was unexpected as biomethane produces twice the net energy per hectare as ethanol. If either biogas losses were reduced or biomethane was utilised in a vehicular engine optimised for biomethane (such as a bus powered solely on gaseous biofuel) then biomethane would generate significantly more net greenhouse gas savings than ethanol. It was found that if biogas losses were eliminated and the biomethane was used in a vehicle optimised for biomethane, then the net greenhouse gas savings are 2.4 times greater than those from ethanol generated from the same feedstock.     

What crop rotation will provide optimal first-generation ethanol production in Ireland, from technical and economic perspectives?

This paper describes a technical and economic analysis of the potential ethanol production from wheat, barley and sugar beet in Ireland for three different combinations of the crops. Scenarios are investigated which include for three crop rotations: (1) wheat, barley and sugar beet; (2) wheat, wheat and sugar beet; and (3) wheat only.Ethanol production facilities typically employ either starch or sugar feedstocks which may not be optimised if both starch and sugar feedstocks are used. Thus, the scenarios which include sugar beet require two separate facilities.The study shows that technical optimisation gives a different rotation to an economic optimisation. It was found that the starch feedstocks (wheat and barley) produce more ethanol per tonne of feedstock than the sugar feedstock (sugar beet). However, on a land area basis, sugar beet produces significantly more ethanol, and hence more energy, than either wheat or barley. In order to meet the EU Biofuels Directive, it is crucial to maximise the energy return per unit of land. Thus, optimisation on the basis of minimisation of land take gives a rotation of wheat, wheat and sugar beet, as this scenario produces the greatest quantity of energy per hectare, whereas optimisation on an economic basis suggests wheat alone with the lowest production cost of €0.6/l.     

An argument for using biomethane generated from grass as a biofuel in Ireland

The Biofuels Directive proposes 5.75% of transport fuel (by energy) to be replaced by biofuel in the year 2010. This equates to 11.3 PJ in Ireland, which equates to 538 million litres of ethanol or 323 million litres of biodiesel. However, if using biodiesel produced through bioesterification of rapeseed oil, then 6.3% of Irish agricultural land is required to produce 5.75% of transport fuel. Furthermore this equates to 70% of arable land.Using ethanol produced from wheat, 3.9% of Irish agricultural land is required to produce 5.75% of transport fuel. Ethanol produces less energy from a crop, than the energy in the biogas generated when the crop is digested. The ethanol production process uses up to 60% of the produced energy in the final ethanol product. It is shown for compressed biomethane generated from silage that the total parasitic demand of the process is of the order of 25%.Grass/silage is a crop that Irish farmers are familiar with, over 90% of Irish agricultural land is under grass. Grass does not require rotation, it does not require annual ploughing (releasing NO_x), and it sequesters carbon into the soil. Digesting silage, scrubbing the biogas to biomethane, and compressing and utilizing it as a transport fuel, is suggested to be the optimum biofuel for Ireland. The 2010 biofuels target can be met with 1.6% of agricultural land; this is four times less land than required using rapeseed. A conservative economic analysis would suggest a lower cost than ethanol produced from wheat.     

Cost-effectiveness analysis of algae energy production in the EU

Today’s society relies heavily on fossil fuels as a main energy source. Global energy demand increase, energy security and climate change are the main drivers of the transition towards alternative energy sources. This paper analyses algal biodiesel production for the EU road transportation and compares it to the fossil fuels and 1st generation biofuels. A cost-effectiveness analysis was used to aggregate private and external costs and derive the social cost of each fuel. The following externalities were internalized: emissions (GHG and non-GHG), food prices impact, pesticides/fertilizers use and security of supply. Currently the social cost of producing algal biodiesel at 52.3 € GJ⁻¹ is higher than rapeseed biodiesel (36.0 € GJ⁻¹) and fossil fuels (15.8 € GJ⁻¹). Biotechnology development, high crude oil prices and high carbon value are the key features of the scenario where algal biodiesel outcompetes all other fuels. A substantial investment into the biotechnology sector and comprehensive environmental research and policy are required to make that scenario a reality.     

Ethanol production from energy crops and wastes for use as a transport fuel in Ireland

The Biofuels Directive places an onus on EU member states to ensure biofuels are available on their markets. This paper investigates the use of ethanol derived from biomass type 1 (residues and wastes) and biomass type 2 (energy crops). The technology involved in generating ethanol from energy crops is mature; the same cannot be said for generation of ethanol from residues; many proposals are mooted to generate ethanol from lignocellulosic biomass, but they are not at a commercial scale. Literature is available however on expected yields and economics of ethanol production from lignocellulosic biomass. This paper investigates three options which produce ethanol: 50 million Lpa of ethanol from sugar beet, 50 million Lpa of ethanol from waste paper and 200 million Lpa of ethanol from waste paper. The economics of ethanol production from sugar beet were the worst of the three due to the requirement to buy the sugar beet. Economies of scale are significant: larger plants produce cheaper ethanol. Indeed it was found that for the large plant, the production cost was zero if a gate fee of €100/t was charged for waste paper. The three options were applied to Ireland. It was found that an investment in an ethanol industry of €561 million would produce 5.7% of the energy value of petrol and diesel in Ireland; the reference value for the minimum portion of biofuels placed on the market in 2010 is 5.75%. The greenhouse-gas savings would equate to 18% of the 1990 transport emissions.     

Biomass and energy yield of industrial hemp grown for biogas and solid fuel

This study examined the energy yield of hemp (Cannabis sativa L.) cultivated for energy purposes under cold climate conditions in Northern Europe. Split-plot field trials were carried out over three consecutive years to investigate different nitrogen fertilisation regimes. Dry matter yield per hectare, moisture content, hydrogen content and heating value were determined at roughly monthly intervals from July until the following spring every season. The energy yield was calculated and adjusted for a fair comparison with those of other energy crops commonly grown in the study region.Two harvest periods for optimal energy yield have been determined; harvest in September to October, when the hemp is used for biogas production, yielded 14.4 Mg ha⁻¹ and 296 GJ ha⁻¹; harvest in February to April, when the hemp is used as a solid fuel, yielded 9.9 Mg ha⁻¹ and 246 GJ ha⁻¹. For biogas production, the adjusted biomass energy yield of hemp was similar to that of maize and sugar beet and 24 and 14% greater than that of lucerne and clover-grass ley, respectively. As a solid fuel, the adjusted biomass energy yield of hemp was 120% higher than that of wheat straw and similar to that of reed canary grass. Annual variations in dry matter yield depending on weather conditions and sowing dates exceeded variations due to nitrogen fertilisation.Hemp is suitable as an energy crop in cold climate regions of Northern Europe, as it has similar or often higher energy yields than other common energy crops grown in these regions.     

A simple rule for bioenergy conversion plant size optimisation: Bioethanol from sugar cane and sweet sorghum

Fuel ethanol from agricultural crops, “bioethanol”, is more expensive than petrol. Here we consider ways to reduce ethanol costs, by using mixed crops to extend the processing season and by optimising plant capacity. We derive a simple model of general applicability by balancing crop transport costs (which increase with plant size) against the (decreasing) production costs. We show that at the optimum, the cost of transporting crop, per unit quantity of alcohol, must be a predictable proportion of the unit cost of production, generally in the range 0.4–0.6. Under current Australian conditions, cane sugar and cane plus sweet sorghum bioethanol plants have optimum capacities around 245,000 and 175,000 kl/year, respectively. the model is equally applicable to any other bioenergy conversion plant which requires biomass to be transported from surrounding areas. The model also shows quantitatively how more efficient transport allows larger scale production, while lower production costs make smaller plants more economic.     

Sugar beet as a biogas substrate? A discrete choice experiment for the design of substrate supply contracts for German farmers

Biogas production using biomass of agricultural origin plays a key role in Germany's energy transition process. As the main substrate, maize usage has been increasingly criticized in recent years leading to a reduction of this crop for the use in biogas plants by an adjustment of Germany's Renewable Energy Sources Act in 2012. Thus, at least 800 biogas plants are obliged by law to find suitable substrate alternatives to maize. This study explores German farmers' willingness to grow sugar beets for biogas production based upon the analysis of a discrete choice experiment conducted with 118 arable farmers. Models are estimated in terms of willingness to accept. Results reveal that at least two-thirds of the participating farmers assess biogas production from sugar beets as a suitable alternative to maize. However, with respect to their own farms, farmers are rather reluctant to choose a contract. Findings also indicate that experience with growing energy crops on contract does not enhance contract acceptance. Furthermore, risk-averse farmers are more likely to contract sugar beet as a biogas substrate than less risk-averse farmers, resulting in a lower price demand. However, risk-averse farmers prefer short contract periods and a small share of their arable land for contracted production, otherwise they demand a markup. Regarding a viable biogas production from agricultural biomass, our study is useful for biogas plant operators, farmers and policy makers to gain insight into the contract design for a possible substrate alternative from the perspective of farmers.     

Technical/economic/environmental analysis of biogas utilisation

Biogas may be utilised for Combined Heat and Power (CHP) production or for transport fuel production (CH₄-enriched biogas). When used to produce transport fuel either electricity is imported to power the plant or some of the biogas is used in a small CHP unit to meet electricity demand on site. The potential revenue from CH₄-enriched biogas when replacing petrol is higher than that for replacing diesel (Irish prices). Transport fuel production when replacing petrol requires the least gate fee. The production of greenhouse-gas is generated with cognisance of greenhouse-gas production with the scheme not in place; landfill of the Organic Fraction of Municipal Solid Waste (OFMSW) (20% of biomass) with and without combustion of landfill gas is investigated. The transport scenario with importation of brown electricity generates more greenhouse-gas than petrol or diesel, when the ‘do-nothing’ case involves combustion of landfill gas. The preferred solution involves transport fuel production with the production of CHP to meet electricity demand on site. A shortfall of this solution is that only 53% of biogas is available for export.     

Energy use and economical analysis of sugar beet production in Tokat province of Turkey

The purposes of this study were to determine energy consumption of input and output used in sugar beet production, and to make a cost analysis in Tokat, Turkey. Data were collected from 146 sugar beet farms in Tokat, Turkey by using a face-to-face questionnaire performed in January and February 2005. Farms were selected based on random sampling method. The results revealed that total energy consumption in sugar beet production was 39 685.51 MJ ha⁻¹, and accounted for 49.33% of fertilizer energy, and 24.16% of diesel energy. The output/input energy ratio was 25.75 and energy productivity was 1.53 kg MJ ha⁻¹. Results further indicated that 82.43% of total energy input was in non-renewable energy form, and only 12.82% was in renewable form. Economic analyses showed that profit–cost ratio of farms was 1.17. The highest energy cost items were labor, land renting, depreciation and fertilizers. Although intensive energy consumption in sugar beet production increased the yield, it also resulted in problems such as global warming, land degradation, nutrient loading and pesticide pollution. Therefore, there is a need to pursue a new policy to force producers to undertake energy-efficient practices to establish sustainable production systems without disrupting the natural resources. In addition, extension activities are needed to improve the efficiency of energy consumption and to sustain the natural resources.     

Improvement potential for net energy balance of biodiesel derived from palm oil: A case study from Indonesian practice

Biodiesel derived from palm oil has been recognized as a high-productivity oil crop among the first generation of biofuels. This study evaluated and discussed the net energy balance for biodiesel in Indonesia by calculating the net energy ratio (NER) and net energy production (NEP) form the total energy input and output. The results of the calculation of energy input for the default scenario demonstrated that the primary energy inputs in the biodiesel production lifecycle were the methanol feedstock, energy input during the biodiesel production process, and urea production. These three items amounted to 85% of the total energy input. Next, we considered and evaluated ways to potentially improve the energy balance by utilizing by-products and biogas from wastewater treatment in the palm oil mill. This result emphasized the importance of utilizing the biomass residue and by-products. Finally, we discussed the need to be aware of energy balance issues between countries when biofuels are transported internationally.     

Sugar beet for bioethanol production: An approach based on environmental agricultural outputs

The EU imports both bioethanol and the raw material needed to produce it. Thirty percent of bioethanol is produced from sugar beets in the EU. However, sugar beet cultivated area and yields have fallen due to the 2006 sugar regime reform. Given the potential uncertainty about the future for sugar beet farmers, biofuels may represent an alternative market. This paper analyses potential contribution to the efficiency, in terms of environmental output, of the sugar beet crop both when production is oriented toward bioethanol and regarding the use of input.An empirical application is performed in Spain by Data Envelopment Analysis (DEA). The results show that 4% of farms have full technical efficiency, while the rest have an average efficiency of 55.9%. The figures show that inputs can be reduced over 40%, and also show the low average level of input-use efficiency. In addition, it cannot be said that there is a relationship between efficiency and farm scale. The consideration of aspects such as the environmental advantages of using sugar beet production for bioethanol can open new lines of action to support this crop in the EU. In addition, boosting sugar beet production may reduce potential dependency on importation.     

Life cycle analysis for bioethanol production from sugar beet crops in Greece

The main aim of this study is to evaluate whether the potential transformation of the existing sugar plants of Northern Greece to modern bioethanol plants, using the existing cultivations of sugar beet, would be an environmentally sustainable decision. Using Life Cycle Inventory and Impact Assessment, all processes for bioethanol production from sugar beets were analyzed, quantitative data were collected and the environmental loads of the final product (bioethanol) and of each process were estimated. The final results of the environmental impact assessment are encouraging since bioethanol production gives better results than sugar production for the use of the same quantity of sugar beets. If the old sugar plants were transformed into modern bioethanol plants, the total reduction of the environmental load would be, at least, 32.6% and a reduction of more than 2 tons of CO₂e/sugar beet of ha cultivation could be reached. Moreover bioethanol production was compared to conventional fuel (gasoline), as well as to other types of biofuels (biodiesel from Greek cultivations).     

Industrial sugar beets to biofuel: Field to fuel production system and cost estimates

Specialized varieties of sugar beets (Beta vulgaris L.) may be an eligible feedstock for advanced biofuel designation under the USA Energy Independence and Security Act of 2007. These non-food industrial beets could double ethanol production per hectare compared to alternative feedstocks. A mixed-integer mathematical programming model was constructed to determine the breakeven price of ethanol produced from industrial beets, and to determine the optimal size and biorefinery location. The model, based on limited field data, evaluates Southern Plains beet production in a 3-year crop rotation, and beet harvest, transportation, and processing. The optimal strategy depends critically on several assumptions including a just-in-time harvest and delivery system that remains to be tested in field trials. Based on a wet beet to ethanol conversion rate of 110 dm³ Mg⁻¹ and capital cost of 128 M$ for a 152 dam³ y⁻¹ biorefinery, the estimated breakeven ethanol price was 507 $ m⁻³. The average breakeven production cost of corn (Zea mays L.) grain ethanol ranged from 430 to 552 $ m⁻³ based on average net corn feedstock cost of 254 and 396 $ m⁻³ in 2014 and 2013, respectively. The estimated net beet ethanol delivered cost of 207 $ m⁻³ was lower than the average net corn feedstock cost of 254–396$ m⁻³ in 2013 and 2014. If for a mature industry, the cost to process beets was equal to the cost to process corn, the beet breakeven ethanol price would be $387 m^-3 (587 $ m⁻³ gasoline equivalent).     

Cost efficient utilisation of biomass in the German energy system in the context of energy and environmental policies

The possible uses of biomass for energy provision are manifold. Gaseous, liquid and solid bioenergy carriers can be alternatively converted into heat, power or transport fuel. The contribution of the different utilisation pathways to environmental political targets for greenhouse gas (GHG) emission reduction and energy political targets for the future share of renewable energy vary accordingly to their techno-economic characteristics. The aim of the presented study is to assess the different biomass options against the background of energy and environmental political targets based on a system analytical approach for the future German energy sector. The results show that heat generation and to a lower extent combined heat and power (CHP) production from solid biomass like wood and straw are the most cost effective ways to contribute to the emission reduction targets. The use of energy crops in fermentation biogas plants (maize) and for production of 1st generation transportation fuels, like biodiesel from rapeseed and ethanol from grain or sugar beet, are less favourable. Optimisation potentials lie in a switch to the production of 2nd generation biofuels and the enhanced use of either biomass residues or low production intensive energy crops.     

Potential of bio-hydrogen production from dark fermentation of crop residues: A review

This study provided an estimate of the potential of bio-hydrogen production from dark fermentation of crop residues on a worldwide scale. The different crop residues reviewed included sugarcane tops, leaves and bagasse, corn straw, corn cob and corn stover, wheat straw, rice straw and husk, soybean straw, oil palm trunk and empty fruit bunch, sugar beet pulp, cassava residue, barley straw and sweet sorghum bagasse. Among these crop residues, wheat and rice straws are produced in the highest amount although sugarcane dominates crop production on a worldwide scale. Based on the bio-hydrogen yields reported in literature, estimated worldwide bio-hydrogen potential is highest for untreated rice straw at 58,002 Mm³/year followed by untreated wheat straw at 34,680 Mm³/year. This corresponds to a bio-energy potential of 623 PJ/year and 373 PJ/year for raw rice straw and wheat straw respectively while pre-treatment of the crop residues significantly increases the bio-hydrogen and bio-energy potential. While dark fermentation of crop residues offers a huge bio-energy potential, the process suffers from several constraints that hinder its implementation. As such, coupling of the dark fermentation process with the anaerobic digestion process as a two-stage process seems the most economically viable option for large-scale implementation.     

Tax exemption for biofuels in Germany: Is bio-ethanol really an option for climate policy?

In 2002 the German Parliament decided to exempt biofuels from the gasoline tax to increase their competitiveness compared to conventional gasoline. The policy to promote biofuels is being justified by their allegedly positive effects on climate, energy, and agricultural policy goals. An increased use of biofuels would contribute to sustainable development by reducing greenhouse-gas emissions and the use of non-renewable resources. The paper takes a closer look at bio-ethanol as a substitute for gasoline. It analyzes the underlying basic German, European, and worldwide conditions that provide the setting for the production and promotion of biofuels. It is shown that the production of bio-ethanol in Germany is not competitive and that imports are likely to increase. Using energy and greenhouse-gas balances we then demonstrate that the promotion and a possible increased use of bio-ethanol to reduce greenhouse-gas emissions are economically inefficient and that there are preferred alternative strategies. In addition, scenarios of the future development of the bio-ethanol market are derived from a model that allows for variations in all decisive variables and reflects the entire production and trade chain of bio-ethanol, from the agricultural production of wheat and sugar beet to the consumption of bio-ethanol in the fuel sector.     

Optimization of bioenergy yield from cultivated land in Denmark

A cost minimization model for supply of starch, oil, sugar, grassy and woody biomass for bioenergy in Denmark was developed using linear programming. The model includes biomass supply from annual crops on arable land, short rotation forestry (willow) and plantation forestry. Crop area distributions were simulated using cost data for year 2005. Five scenarios with different constraints, e.g. on food and feed supply and on nitrogen balance were considered focusing on: a) constraints as the year 2005, b) landscape aesthetics and biodiversity c) groundwater protection, d) maintaining current food and feed production, or e) on site carbon sequestration. In addition, two oil price levels were considered. The crop area distributions differed between scenarios and were affected by changing fossil oil prices up to index 300 (using 55$ per barrel in 2005 as index = 100). The bioenergy supply (district heating, electric power, biogas, RME or bioethanol) varied between 56 PJ in the “2005” scenario at oil index 100 and 158 PJ at oil index 300 in the groundwater scenario. Our simple model demonstrates the effect of prioritizing multiple uses of land resources for food, feed or bioenergy, while maintaining a low nitrogen load to the environment. In conclusion, even after drastic landuse changes the bioenergy supply as final energy will not exceed 184 PJ annually (including 26 PJ processed biowaste sources) by far lower than the annual domestic total energy consumption ranging between 800 and 850 PJ yr^?1.     

Liquid biofuels potential and outlook in Iran

Iran’s diversity of terrain and climate enables cultivation of a variety of energy crops suitable for liquid biofuels production. In Iran, the easily and readily available biofuel feedstock today for production of bioethanol is molasses from sugar cane and sugar beet. There is also about 17.86 million tons of crops waste from which nearly 5 billion liters of bioethanol could be produced annually. This amount of bioethanol is sufficient to carry out E10 for spark ignition engine vehicles in Iran by 2026. There is also enormous potential for cultivation of energy plants such as cellulosic materials and algae. Iran has 7%of its area covered with forest products which are suitable sources for liquid biofuels such bioethanol and biodiesel. Iran also has a long tradition of fishing in Caspian Sea and Persian Gulf with about 3200 km coastline and on inland rivers. The produced fish oil and other plant oils such as palm tree, jatropha, castor plant and algae are suitable biodiesel feedstock. Out of 1.5 million tons of edible cooking oil consumed in Iran annually, about 20% of it can be considered as waste, which is suitable biodiesel feedstock.This quantity along with the other possible potential feedstock are favorable sources to carry out B10 step by step until 2026.     

Co-digestion of poultry manure and residues from enzymatic saccharification and dewatering of sugar beet pulp

This study investigates the co-digestion of poultry manure (PM) with sugar beet pulp residues (SBPR) obtained from saccharification and dewatering of sugar beet pulp. The laboratory-scale experiments were conducted under batch and semi-continuous conditions at mesophilic temperatures (35 °C). Batch tests gave specific biogas and methane yields of 590 dm³/kgVS_fed and 423 dm³CH₄/kgVS_fed, respectively for SBPR, whereas the corresponding values for PM were 434 dm³/kgVS_fed and 300 dm³CH₄/kgVS_fed. The co-digestion of PM with SBPR was found to increase biogas and methane yields compared to the manure alone. In semi-continuous reactor experiments, the highest methane yield of 346 dm³ CH₄/kgVS_fed was achieved for the mixture containing poultry manure with 50% SBPR (weight basis) and a solids retention time (SRT) of 20 days. However, when poultry manure was digested as a sole feedstock, the biogas production was inhibited by ammonia, whereas the co-digestion of PM with 25% SBPR was slightly affected by volatile fatty acids, which concentrations exceeded 4000 g/m³.