Bio-synthetic Natural Gas Research Articles

Drop-in and hydrogen-based biofuels for maritime transport: Country-based assessment of climate change impacts in Europe up to 2050

Alternative fuels are crucial to decarbonize the European maritime transport, but their net climate benefits vary with the type of fuel and production country. In this study, we assess the energy potential and climate change mitigation benefits of using agricultural and forest residues in different European countries for drop-in (Fast Pyrolysis, Hydrothermal Liquefaction, and Gasification to Fischer-Tropsch fuels or Bio-Synthetic Natural Gas) and hydrogen-based biofuels (hydrogen, ammonia, and methanol) with or without carbon capture and storage (CCS). Our results show the combinations of countries and biofuel options that successfully achieve the decarbonization targets set by the FuelEU Maritime initiative for the next years, including a prospective analysis that include technological changes projected for the biofuel supply chains until 2050. With the current technologies, the largest greenhouse gas (GHG) mitigation potential per year at a European scale is obtained with bio-synthetic natural gas and hydrothermal liquefaction. Among carbon-free biofuels, ammonia currently has higher mitigation, but hydrogen can achieve a lower GHG intensity per unit of energy with the projected decarbonization of the electricity mixes until 2050. The full deployment of CCS can further accelerate the decarbonization of the maritime sector. Choosing the most suitable renewable fuels requires a regional perspective and a transition roadmap where countries coordinate actions to meet ambitious climate targets.

Supercritical CO2 utilization in a CO2 zero emission novel system for bio-synthetic natural gas, power and freshwater productions

Supercritical CO2 utilization is of interest because its supercritical conditions are easily accessible. Supercritical CO2 was utilized in this study in a Brayton cycle driven by a biomass gasification for power production and preheating a humidification-dehumidification desalination system. Biomass gasification triggered a methanation reactor for production of a bio-synthetic natural gas which is a synthetic natural gas obtained from a biomass resource. This technology has a promising performance because it approximately does not have carbon dioxide emission and producing bio-synthetic natural gas from a biomass gasification using a methanation reactor is a carbon dioxide negative technology. Response surface methodology has been utilized for comprehensive investigation and multi-objective optimization of the novel tri-generation system considering power production, freshwater flow rate, and methane content in bio-synthetic natural gas as criteria and selecting biomass feed rate, steam to biomass ratio and pressure ratio of supercritical carbon dioxide Brayton cycle as variable parameters. What stands out in results of analysis of variance is the dominance of biomass feed rate in shares on outputs. Biomass feed rate of 1.2 mol/s, steam to biomass ratio of 1.5 and pressure ratio of 3.5 resulted in the optimum response variables of power production of 172.6 kW, freshwater flow rate of 778.8 kg/hr, and methane content of 50.8% in bio-synthetic natural gas.

Parametric Study on the Adjustability of the Syngas Composition by Sorption-Enhanced Gasification in a Dual-Fluidized Bed Pilot Plant

Finding a way for mitigating climate change is one of the main challenges of our generation. Sorption-enhanced gasification (SEG) is a process by which syngas as an important intermediate for the synthesis of e.g., dimethyl ether (DME), bio-synthetic natural gas (SNG) and Fischer–Tropsch (FT) products or hydrogen can be produced by using biomass as feedstock. It can, therefore, contribute to a replacement for fossil fuels to reduce greenhouse gas (GHG) emissions. SEG is an indirect gasification process that is operated in a dual-fluidized bed (DFB) reactor. By the use of a CO2-active sorbent as bed material, CO2 that is produced during gasification is directly captured. The resulting enhancement of the water–gas shift reaction enables the production of a syngas with high hydrogen content and adjustable H2/CO/CO2-ratio. Tests were conducted in a 200 kW DFB pilot-scale facility under industrially relevant conditions to analyze the influence of gasification temperature, steam to carbon (S/C) ratio and weight hourly space velocity (WHSV) on the syngas production, using wood pellets as feedstock and limestone as bed material. Results revealed a strong dependency of the syngas composition on the gasification temperature in terms of permanent gases, light hydrocarbons and tars. Also, S/C ratio and WHSV are parameters that can contribute to adjusting the syngas properties in such a way that it is optimized for a specific downstream synthesis process.

Techno-Economic and Life Cycle Impacts Analysis of Direct Methanation of Glycerol to Bio-Synthetic Natural Gas at a Biodiesel Refinery

An economic and environmental feasibility study were carried out on the thermochemical conversion of glycerol to medium methane content biological synthetic natural gas (bio-SNG). A plant that processed 497 kg·h−1 of glycerol to bio-SNG was modelled as an on-site addition to a soybean biodiesel plant based in Missouri (USA) that produced 30 million litres of soybean biodiesel per year. Assuming the glycerol contained only 80 wt% free glycerol, the bio-SNG could substitute up to 24% of the natural gas at the soybean biodiesel plant. The discounted cash flow analysis showed it was possible to generate positive NPVs and achieve internal rates of return within the hurdle rate (12%) for biomass gasification technologies. From the environmental analysis it was found that the bio-SNG could reduce global warming potential by 28% when compared to conventional natural gas in the USA and translates to roughly 7% reduction in biodiesel natural gas emissions, if the maximum 24% of natural gas were to be substituted by bio-SNG. The work highlights the potential to divert waste glycerol to an onsite energy vector at soybean biodiesel plants with minimal change to the main biodiesel production process and potential reductions to soybean biodiesel global warming potential.

The techno-economic viability of bio-synthetic natural gas production utilising willow grown on contaminated land

The growth of energy crops on contaminated land offers two potential advantages over their growth on agricultural land. Firstly, it can clean the land of contaminants, remediating it for future development or agricultural use. Secondly by growing energy crops on such land there is no conflict with land that is suitable for other uses (primarily agriculture). This study examines the opportunity to grow willow on contaminated land and to use this crop to produce bio-synthetic-natural-gas via the gasification processing route. The impact on the gasification system of using the contaminated materials as a feedstock is examined. A process that utilises a steam and oxygen blown gasifier with a plasma gas cleaning step and subsequent syngas cleaning is found most effective. An economic analysis of the process is undertaken to assess the viability of the opportunity. The results show that the costs associated with using the system to remediate land are lower than conventional alternatives, but require forward temporal planning which is not often evident or possible. Cost viability, if considered only for energy production, depends on the feedstock selling for a significantly lower price than virgin feedstock (in many cases requiring a gate fee), alongside a combination of strong policy incentives, natural gas prices and a long-term demand for gas products. For a 20 MW output system the feedstock would require a gate fee of £30 or £70 per tonne (depending on the policy support claimed), whilst for a 50 MW system a £25 gate fee or £30 cost per tonne are needed. Larger gasifiers are more economically viable, but provision of material grown from contaminated land would be unlikely to fulfil demand. Therefore, coupling systems with waste material as a feedstock is beneficial, but has resultant policy implications as current financial incentives are different for such materials.

Integration of an Electrolysis Unit for Producer Gas Conditioning in a Bio-Synthetic Natural Gas Plant

Producer gas from biomass gasification contains impurities like tars, particles, alkali salts, and sulfur/nitrogen compounds. As a result, a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into synthetic natural gas (SNG). A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of syngas produced. Internal rate of return (IRR) is evaluated as an economic indicator of the processes considered. Results indicate that, depending on process configuration, the production of SNG can be boosted by approximately 50–60% without the need of an additional carbon source, i.e., for the same biomass input as in standalone operation of the GoBiGas plant.

Systems analysis of different value chains based on domestic forest biomass for the production of bio-SNG

This study compares value chains based on domestic forest biomass for the production of bio–synthetic natural gas (SNG) with respect to economic performance, GHG emissions, and energy efficiency. Value chains in which raw material is upgraded to intermediate products before transportation to an SNG plant integrated with a district heating system for further upgrading are compared with a chain in which the raw material is transported directly to the SNG plant. The intermediates considered are either dried biomass from forest residues, or bark, upgraded at pulp mills, or pellets from sawdust upgraded at sawmills. The findings show that the difference in performance between the studied value chains is generally small. The highest cost and significantly lowest energy efficiency are associated with the value chain with pellets, which leads to the conclusion that more pretreatment than what is required by the SNG process, to lower transport costs, is not profitable. Drying forest residues at pulp mills before further transportation to and upgrading at an SNG plant leads to somewhat higher transportation costs because of the relatively high fixed costs associated with transportation. However, the benefit of drying the biomass using excess heat at pulp mills is that heat is “moved” from a location, where it can be hard to find profitable ways to use it, to the SNG plant, where the excess heat can be used for district heating. With these two factors working in opposition, the total cost is similar if forest residues are transported directly to the SNG plant or via a pulp mill. The lowest cost is achieved when falling bark from pulp mills is used because the first transportation step is avoided and no additional investment for biomass handling at the mill is required. However, there is a technical uncertainty regarding how much bark can be used in the SNG process.

The BioSCWG Project: Understanding the Trade-Offs in the Process and Thermal Design of Hydrogen and Synthetic Natural Gas Production

This article presents a summary of the main findings from a collaborative research project between Aalto University in Finland and partner universities. A comparative process synthesis, modelling and thermal assessment was conducted for the production of Bio-synthetic natural gas (SNG) and hydrogen from supercritical water refining of a lipid extracted algae feedstock integrated with onsite heat and power generation. The developed reactor models for product gas composition, yield and thermal demand were validated and showed conformity with reported experimental results, and the balance of plant units were designed based on established technologies or state-of-the-art pilot operations. The poly-generative cases illustrated the thermo-chemical constraints and design trade-offs presented by key process parameters such as plant organic throughput, supercritical water refining temperature, nature of desirable coproducts, downstream indirect production and heat recovery scenarios. The evaluated cases favoring hydrogen production at 5 wt. % solid content and 600 °C conversion temperature allowed higher gross syngas and CHP production. However, mainly due to the higher utility demands the net syngas production remained lower compared to the cases favoring BioSNG production. The latter case, at 450 °C reactor temperature, 18 wt. % solid content and presence of downstream indirect production recorded 66.5%, 66.2% and 57.2% energetic, fuel-equivalent and exergetic efficiencies respectively.

Biomass gasification for natural gas substitution in iron ore pelletizing plants

The ore fines' pelletizing is an important part of iron mining, which ensures better use of natural resources and increases the blast furnace efficiency. However, this process consumes high amounts of non-renewable energy, such as natural gas (NG) and coke. Due to fossil fuel scarcity and global warming issues, at least partial substitution for renewable energy is desirable. Biomass gasification projects are being successfully developed in Northern Europe and large-scale circulating fluidized bed (CFB) biomass gasifiers have been commissioned. This work compares different technologies, such as CFB air and oxygen gasification, dual fluidized bed (DFB) steam gasification, and bio-synthetic natural gas (bio-SNG) production, focusing on the use of the product gas in an iron ore pelletizing process located in the Southeast of Brazil. The main parameters evaluated were flame temperature and gaseous flow rates. Economical evaluation was also performed. Air gasification provided a product gas with the lowest energy content but it was the most attractive investment. Oxygen gasification is apparently the best option as it provides a product gas with higher heating value at almost the same cost as air gasification. In both cases changes to the burners would be required. Bio-SNG could be utilized without any adaption in the indurating machine; however, it is still more expensive than NG.

Evaluation of next generation biomass derived fuels for the transport sector

This paper evaluates next generation biomass derived fuels for the transport sector, employing the Analytic Hierarchy Process. Eight different alternatives of fuels are considered in this paper: bio-hydrogen, bio-synthetic natural gas, bio-dimethyl ether, bio-methanol, hydro thermal upgrading diesel, bio-ethanol, algal biofuel and electricity from biomass incineration. The evaluation of alternative fuels is performed according to various criteria that include economic, technical, social and policy aspects. In order to evaluate each alternative fuel, one base scenario and five alternative scenarios with different weight factors selection per criterion are presented. After deciding the alternative fuels’ scoring against each criterion and the criteria weights, their synthesis gives the overall score and ranking for all alternative scenarios. It is concluded that synthetic natural gas and electricity from biomass incineration are the most suitable next generation biomass derived fuels for the transport sector.

Bio-synthetic natural gas as fuel in steel industry reheating furnaces – A case study of economic performance and effects on global CO2 emissions

Climate change is of great concern for society today. Manufacturing industries and construction account for approximately 20% of global CO2 emissions and, consequently, it is important that this sector investigate options to reduce its CO2 emissions. One option could be to substitute fossil fuels with renewable alternatives. This paper describes a case study in which four future energy market scenarios predicting 2030 were used to analyse whether it would be profitable for a steel plant to produce bio-SNG (bio-synthetic natural gas) in a biomass gasifier and to substitute LPG (liquefied petroleum gas) with bio-SNG as fuel in reheating furnaces. The effects on global CO2 emissions were analysed from a perspective in which biomass is considered a limited resource. The results from the analysis show that investment in a biomass gasifier and fuel conversion would not be profitable in any of the scenarios. Depending on the scenario, the production cost for bio-SNG ranged between 22 and 36 EUR/GJ. Fuel substitution would reduce global CO2 emission if the marginal biomass user is a producer of transportation fuel. However, if the marginal user of biomass is a coal power plant with wood co-firing, the result would be increased global CO2 emissions.