Fossil Energy Demand Research Articles

A straw-soy protein composite (SSPC) material: preparation, physical properties and wetting drying stability

The use of bio-based biomass construction materials has the advantage of helping to reduce fossil energy demand, protecting the environment from carbon dioxide emission and reducing the production of non-degradable waste. This paper used resin-modified soy protein (SP) adhesive to combine rice straw stalks, and made straw-soy protein composites (SSPC) material. The physical properties, compressive behavior and stability during wetting drying cycles of SSPC were measured. Due to water evaporation, the SP matrix is full of connected pores, resulting to its physical properties of small density, high shrinkage ratio and low thermal conductivity, which are 0.24 g/cm3, 16.2%, and 0.065 W/(m•K), respectively. Adding straw is helpful to the physical properties of SP matrix, leading to an obvious decrease in shrinkage ratio and thermal conductivity of SSPC, which are 8.51% and 0.075 W/m•K. Furthermore, the compressive load–displacement curves of SSPC groups divide into two types: divergent and convergent. The compressive strength of divergent samples is decided by the critical displacement determined according to the convergent specimens. It shows that straw stalk proves the positive effect on the compressive property of SP matrix. As to the mass of SSPC samples during the wetting drying cycles, it drops apparently in the initial three cycles, and becomes negligible from the fifth cycle, meaning that the stability of SSPC during wetting drying cyclic process is quite good. The research result would be helpful for using SSPC as building material, especially as thermal insulation material.

The environmental performance of zero-emission buildings in a fossil-free energy system

Buildings can play an important role in reducing GHG emissions through increased energy efficiency. The European Commission mandates that all new buildings should be “zero emission buildings” (ZEB), aiming at a zero GHG emission building stock by 2050. The extent to which ZEB can contribute to reduced GHG emissions, however, varies between countries, due to different energy systems. It is also important to consider other environmental effects to avoid that climate benefits come with unintended consequences. Here, we explore the life-cycle environmental performance for a ZEB in a case where electricity and heating are largely fossil-free. The assessment concentrates on i) environmental impact of the use stage in relation to the product stage, ii) the interrelation between different energy sources, with focus on household electricity, and iii) the performance for more impact categories than primary energy use and climate change. While our results generally support the use of ZEBs from an environmental perspective, they also show that the climate benefit in this setting is marginal. However, given that energy systems are connected and energy savings in one place can reduce the demand for fossil energy elsewhere, the climate benefit of ZEBs is likely underestimated. Besides methodological implications for future studies, this indicates that current EU policy is promising, as incentives for implementation of ZEBs are unaffected by domestic effects.

Mitigating policies for pollutant emissions in a DSGE for the Brazilian economy

This paper examines the dynamic behavior of the Brazilian economy under policy regimes aimed at controlling pollutant emissions and limiting environmental damage. Greenhouse gas (GHG) emissions are assumed to be of two types: carbon from fossil resources burning for energy generation (i.e., thermoelectric) or carbon and non-carbon outputs from production processes (i.e., methane from cattle). Firms optimally decide on the demand for fossil and green energy, as the level of effort dedicated to abating emissions coming from production processes. Two alternative policies for emissions, which include emissions taxation (fixed cost) and emission permits trade (quantity caps), are introduced into an open-economy DSGE model for the Brazilian economy. Departing from the estimated parameters of the original version of the model, ratios in the new block of equations for the energy and emissions are calibrated using sectoral data, and some elasticities are set to reproduce the sensibility to some shocks implicit in the NGFS11Network for Greening the Financial System. scenarios (Net Zero 2050). Simulations indicate neither of the emissions policies can induce transition in the energy matrix without a green investment policy. The approach adopted here is a first step in building a macroeconomic model capable of challenging scenarios from more specialized models dedicated to energy and emissions by better assessing possible effects and feedback related to the iterations with macroeconomic dynamics. Despite the difficulties concerning the limited availability of data in higher frequency, results indicate those modeling approaches are sufficiently flexible to incorporate the main aspects of energy and emission, serving as valuable tools for policy analysis.

Environmental impacts of Australian pork in 2020 and 2022 determined using lifecycle assessments

Context The Australian pork industry is highly efficient, with a history of ongoing productivity and environmental improvement. The introduction of economy-wide environmental targets require delivering and tracking performance improvement. Aims This study determined carbon footprint (greenhouse gas [GHG] and land use [LU] and direct land use change [dLUC] emissions, reported as kg CO2-e), fossil energy (MJ), freshwater consumption (L), water stress (L H2O-e), land occupation (m2) and eutrophication potential (nitrogen and phosphorus) for Australian pork for 2020 and 2022. Variability between housing, manure management systems, and regions were identified, and systems analysed to determine new options for low-impact pork. Methods In the largest Australian study of its kind, data for ~70% of pigs produced were collected using a stratified design. Using attributional life cycle assessment, impacts were reported per kilogram of liveweight (LW), post-processed, retail, and boneless, fat-corrected pork. Results are presented as industry averages ± 2 × s.d. Key results Key results were 3.0 ± 0.1 and 3.0 ± 0.1 kg CO2-e GHG, 0.4 ± 0.07 and 0.3 ± 0.03 kg CO2-e LU and dLUC, 12.9 ± 0.5 and 13.4 ± 0.5 MJ, 93.8 ± 9.6 and 52.5 ± 3.6 L, 68.4 ± 6.7 and 43.2 ± 3.3 L H2O-e, and 12.0 ± 0.9 and 12.7 ± 0.9 m2/kg LW in 2020 and 2022, respectively. Due to industry growth, total emissions were higher in 2022. Eutrophication potential for Australian pork (2.2 × 10−4 ± 3.0 × 10−5 kg phosphorus and 8.7 × 10−3 ± 3.5 × 10−4 kg nitrogen/kg LW), reported for the first time, was low compared with grazing systems and European piggeries. Conclusions Industry has demonstrated long-term performance improvement, though the rate slowed between 2020 and 2022. Ongoing interventions are required to return to trend. Covered pond, deep litter, and outdoor systems produce lower carbon footprint pork and can provide other environmental benefits from renewable energy, and reduced fossil energy demand. Implications There is potential to further reduce environmental impacts through practice change. If industry is to meet formal targets, investment and proactive policy settings are required to overcome barriers to adoption of existing technology and support the techno-economic case for novel strategies.

The stimulating effects of international emission price fluctuations on bioenergy development of an energy-importing economy

An increase in emission price creates economic incentives because bioenergy producers could sell bioenergy and realize values attached to emission offset. Recently, the termination of the short-term goal of carbon neutrality in some European countries has skyrocketed, and demand for fossil energy has increased, as has the emission price. This situation brings challenges and opportunities to an energy-importing economy like Taiwan, which relies on fossil imports and is vulnerable to price distortions but also gets a chance to develop low-carbon energy domestically. This study proposes a mathematical programming model to investigate how such variations in emission price would affect bioenergy development from energy crops and how bioenergy producers with different production possibilities would behave in uncertain market conditions. Some insightful results are explored. First, bioenergy producers would change their production strategies from energy-focused technologies to emission-oriented ones because the gain from co-products would make emission offset more profitable. At a high emission price, biopower production declines from 11,492 GWh to about 3315 GWh. Still, more than 8.73 million tons of biochar is produced, and the total offset from bioenergy and biochar sequestration expands to 33.7 million tons of CO2. Second, the production pattern of energy crops varies substantially under market conditions. Energy crop plantation at low energy prices is 227,000–263,000 ha but expands to 638,000–798,000 ha when energy and emission prices increase. Third, reducing bioenergy production does not necessarily minimize social welfare because the gain from carbon sequestration may outweigh the loss from reduced bioenergy production at high emission prices. Potential policies that can be applied to adjust production strategies are also discussed in detail.

Advances in electrocatalytic carbon dioxide reduction reactors, electrolytes and catalysts

With the advance of The Times, people's demand for fossil energy has greatly increased, and it is the main energy for people to develop economy and science and technology. However, the large-scale exploitation of fossil energy has led to environmental pollution and energy crisis, and the concentration of CO2 in the air continues to rise, and the greenhouse effect is becoming more and more serious. Therefore, the conversion of CO2 into the high value-added fuels and chemicals we need will be a major measure to solve environmental problems. So, converting CO2 into fuels or high value-added chemicals using CO2 electrocatalytic reduction (CO2RR) technology is an effective way to alleviate the current problems of energy and environment. In this paper, we summarize the research progress in reaction systems, electrolyte effects, and catalyst development in CO2RR experiments, focusing on the electrocatalytic aspects of CO2. Finally, we provide an outlook on the CO2 electrocatalysis industry.

Is lithium from geothermal brines the sustainable solution for Li-ion batteries?

The rising demand for Li, paramount for energy storage, necessitates expanded supply. As the supply is concentrated in a few countries, this poses supply chain risks for Li-ion battery makers. To diversify suppliers, alternative Li ore deposits such as geothermal brines are being explored. However, Li extraction from geothermal brines is challenging due to the unique chemistry and elevated temperatures. Since Li-extraction from geothermal brines is in its infancy, data availability and quality are still poor, hampering life cycle assessments. Hence, this study provides a parametrized life cycle inventory model of Li carbonate production from geothermal brines. The model accounts for site-specific environmental conditions and technological features. Life cycle impacts at the Salton Sea in the US (1686 cases) and the Upper Rhine Graben in Germany (1982 cases) are quantified. The high case numbers are chosen to mitigate the high uncertainties in input parameters. Specifically, the brine chemistry, adsorption yield, drilling required and energy inputs are varied. Climate change impacts of selected cases vary within 18–59 kg CO2eq/kg Li carbonate at the Salton Sea and within 5.3–46 kg CO2eq/kg Li carbonate at the Upper Rhine Graben, compared to 2.1–11 kg CO2eq/kg Li carbonate in existing ecoinvent data sets. The wide range of potential impacts underscore the necessity of early-stage assessments of the technologies. In case of high drilling demand and use of fossil energy, climate change impacts of Li-ion batteries using Li carbonate from geothermal brines can increase by 30–41 % compared to literature values.

Life cycle assessment of mycelium-based composite materials

Mycelium-based composites (MBCs) show promising acoustic and thermal insulation, fire safety, and mechanical strength properties and are suitable for multiple applications in the construction, packing or furniture industry. A life cycle assessment confirmed climate change and fossil energy demand benefits in a laboratory scale production modelled for Germany. MBC are associated with 0.3668 kg CO2e / kg MBC (EN 15804 + A2). The electricity required to run MBC production and hemp cultivation, if used as a substrate, contribute significantly to the environmental impact categories considered. Compared to conventional insulation materials, environmental advantages of MBC can be confirmed. Particularly, MBC has a better climate change impact than extruded polystyrene, quadcore sandwich panel, foam concrete and rockwool. However, since the end-of-life is not assessed, the wood-fiber and straw panels perform better regarding climate change. Moreover, MBC has lower fossil energy demand than all conventional insulation materials. Land-use and water demand are higher than for conventional materials.

An evaluation of the impact of China's green credit policy on different pathways using a CGE model.

The objective of the study was to quantitatively analyze the heterogeneous effects of different green credit implementation methods on energy, environmental, and economic systems by developing a computable general equilibrium model. The specific green credit implementation methods are divided into interest-penalty policy for energy-intensive industries andinterest preferential policy for green industries. Various approaches to implementing green credit can lead to distinct impacts on energy consumption, environmental outcomes, and economic performance. Green credit policy experiments are carried out utilizing short-, medium-, and long-term scenarios to investigate how the consequences of green credit policies evolve. The findings demonstrate that (1) implementing a penalty interest policy for energy-intensive industries can have substantial short-term environmental effects, cutting total demand for fossil energy and lowering carbon dioxide emissions significantly. As the cycle progresses, this effect will progressively fade and have a negative economic impact. (2) The interest preferential policy for the green industry has a significant promoting effect on green technology, and its energy and environmental effects will be reflected in the long term, and the effect will continue to increase, which has a positive promoting effect on the economy. (3) There are significant differences in the policy effects brought about by the different implementation methods of green credit policies. Both policies can positively affect social energy and the environment, but the effect cycles are different. When two types of interest policies are implemented in the economy, the negative economic effect of the penalty interest policy is greater than the positive effect of the preferential interest policy, which harms the macroeconomy. These conclusions will provide theoretical and practical references for the government and banks to choose a better green credit implementation path.

Retraction: Fossil energy demand and economic development in BRICS countries

Retraction: Fossil energy demand and economic development in BRICS countries

Uncertainty quantification of reservoir performance using machine learning algorithms and structured expert judgment

The increasing demand for fossil energy necessitates forecasting of reservoir performance and informed decision-making under various production scenarios. Although reservoir models are used to make such forecasts, neglecting geological uncertainties and history matching can limit the understanding of reservoir production behavior. While performing reservoir simulation on multiple models for uncertainty quantification is a direct approach, it is associated with significant time and computational costs and low convergence rates. This study proposes a method to address these limitations using Bayes' theorem integrated with Machine Learning (ML) algorithms, sampling methods (Markov Chain Monte Carlo and rejection), and Structured Expert Judgment (SEJ) based on the Cooke's Model (CM). The tuned ANN model outperforms traditional simulation methods in terms of computational cost when predicting posterior probability distributions, while also displaying high accuracy as confirmed by R2-score and k-fold cross-validation analyses. Furthermore, using trained ANN models in conjunction with representative samples drawn from posterior probability distributions enables the rigorous prediction of reservoir production parameters. Finally, the CM is implemented to generate a robust model by combining the statistical quantiles, including P10–P25–P50–P75–P90 estimations obtained from MCMC and rejection sampling. The applicability of this methodology is demonstrated for Teal South reservoir with eight uncertain parameters.

Intervening long-run fundamentals of fossil energy demand-an effort towards responsible and clean energy consumption.

Energy is crucial for growth, but over-reliance on fossil energy undermines sustainability. COP27 has emphasized over transition towards clean energy. Empirical studies have pointed out that energy transition requires infrastructure development which is costly in the short run. Global and national efforts to transition to renewable energy require investigating what matters in global fossil energy demand. While empirical studies have focused on motivating renewable energy, this study explores the determinants of fossil energy in anticipation of reducing its reliance and moving towards sustainable development goals. A non-linear panel quantile ARDL regression was deployed using data from 137 countries and showed that increased forest and natural resource rents and health expenditures are already playing their role. The quadratic models highlighted the importance of optimizing resource rents to nudge the renewable resource decision. Now, policymakers need to intervene in terms of income, education, and fossil energy rents to help households and firms prefer renewable energy sources and move towards sustainability.

Driving factors of energy related CO2 emissions at a regional level in the residential sector of Iran

Iran has increased its CO2 emissions significantly during the past few decades. The household sector in Iran contributes one of the largest sectors of CO2 emissions. Despite this significant contribution, the existing policies have predominantly concentrated on large-scale initiatives while overlooking the regional role in shaping and implementing these plans. Therefore, this study investigates the relationship between CO2 emissions and the efficient factors in three major groups including energy, climate, and household socio-economic factors. This study aims to address regional carbon emissions and develop CO2 reduction policies tailored to each region's specific circumstances. It focuses on planning strategies at the regional level to effectively tackle CO2 emissions. Household panel data of 28 provinces of Iran are employed by using both static and dynamic panel models for the years 2001 to 2019. Static estimation includes Fixed Effect (FE), Random Effect (RE) and pooled Partial least squares (PLS), Dynamic estimation includes difference Generalized Method of Moments (GMM) and system Generalized Method of Moments (GMM). The empirical result of the static method showed positive dependence of household CO2 emissions on Heating Degree Days (HDD), Cooling Degree Days (CDD), precipitation level, oil consumption, gas consumption, household income, size of household, and also building stocks. In more detail, educational rate, dummy variable (removal of energy subsidy), and oil price reveal the greatest negative impact on the emissions with elasticities of − 0.428, − 0.31, and − 0.15; It represents 1% increase causes − 0.428, − 0.31, − 0.15, decrease CO2 emissions, respectively. however, household size, gas consumption, and oil consumption show the most significant positive effects on CO2 emissions with 1 percent increase causes CO2 emissions increases by 0.1, 0.044, and 0.026, respectively. Regarding the impact of climate factors, a 1% increase in Heating Degree Days, Cooling Degree Days, and precipitation level causes CO2 emissions increase by 0.024%, 0.004%, and 0.011% respectively, due to an increase in fossil energy demand. Results of the dynamic method of the system Generalized Method of Moments are similar to the static estimation results, except for that household size and urbanization are not significant. Also, removing the energy subsidy for fossil fuels due to substantial subsidy in fossil fuels in Iran or implementing a re-pricing energy policy can be a beneficial way to control carbon emissions from households within the provinces of the country. However, it is important to consider that this shift could potentially transfer subsidies to investments in the private sector for renewable energies.

China's carbon emissions and energy demand under different methods of global mitigation cooperation: Application of an extended RICE model with energy details

This study extends the classic RICE model by introducing energy factors into the economic module and comprehensively describes different types of energy demands. Taking China as an example, we constructed the RICE-China model and further explored the impact of different cooperation methods on China's carbon emissions and energy demand. The main results are as follows. First, there are significant differences in China's emission reduction under different cooperation scenarios. In the Lindahl cooperation scenario, China's carbon emissions in 2100 have reduced by 90.5 % to achieve the two-degree goal, which is lower than the utilitarian cooperation scenario. Second, the decline in China's fossil energy under the utilitarian scenario is higher than that under the Lindal scenario. Specifically, China's fossil energy demand decreased by 91.4 % in 2100 under the Lindal scenario, with non-fossil energy accounting for 94.7 % of total energy consumption. Third, China's emission reduction in the later period under the RICE-China model is lower than that of the RICE model, and the corresponding GDP loss has also decreased. Specifically, China's GDP losses under the RICE-China model are approximately 1.5–2.8% points lower than those under the RICE model. This study provides new insights for China to participate in international climate cooperation.

From straw to salmon: a technical design and energy balance for production of yeast oil for fish feed from wheat straw

BackgroundAquaculture is a major user of plant-derived feed ingredients, such as vegetable oil. Production of vegetable oil and protein is generally more energy-intensive than production of the marine ingredients they replace, so increasing inclusion of vegetable ingredients increases the energy demand of the feed. Microbial oils, such as yeast oil made by fermentation of lignocellulosic hydrolysate, have been proposed as a complement to plant oils, but energy assessments of microbial oil production are needed. This study presents a mass and energy balance for a biorefinery producing yeast oil through conversion of wheat straw hydrolysate, with co-production of biomethane and power.ResultsThe results showed that 1 tonne of yeast oil (37 GJ) would require 9.2 tonnes of straw, 14.7 GJ in fossil primary energy demand, 14.6 GJ of process electricity and 13.3 GJ of process heat, while 21.5 GJ of biomethane (430 kg) and 6 GJ of excess power would be generated simultaneously. By applying economic allocation, the fossil primary energy demand was estimated to 11.9 GJ per tonne oil.ConclusionsFossil primary energy demand for yeast oil in the four scenarios studied was estimated to be 10–38% lower than for the commonly used rapeseed oil and process energy demand could be met by parallel combustion of lignin residues. Therefore, feed oil can be produced from existing non-food biomass without causing agricultural expansion.

Regulating the Electronic Structure of Ni Sites in Ni(OH)2 by Ce Doping and Cu(OH)2 Coupling to Boost 5-Hydroxymethylfurfural Oxidation Performance.

Biomass is a sustainable and renewable resource that can be converted into valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be converted to high-value-added 2,5-furandicarboxylic acid (FDCA) via a green and renewable electrocatalytic oxidation route under mild reaction conditions, but efficient electrocatalysts are still lacking. Herein, we rationally fabricate a novel self-supported electrocatalyst of core-shell-structured copper hydroxide nanowires@cerium-doped nickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu) for electrocatalytically oxidizing HMF to FDCA. The integrated configuration of composite nanowires with rich interstitial spaces between them facilitates fast mass/electron transfer, improved conductivity, and complete exposure of active sites. The doping of Ce ions in nickel hydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide nanowires (CuH_NWs) regulate the electronic structure of the Ni active sites and optimize the adsorption strength of the active sites to the reactant, meanwhile promoting the generation of strong oxidation agents of Ni3+ species, thereby resulting in improved electrocatalytic activity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst is able to achieve a HMF conversion of 98.5% with a FDCA yield of 97.9% and a Faradaic efficiency of 98.0% at a low constant potential of 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity attenuation can be found after 15 successive cycling tests. Such electrocatalytic performance suppresses most of the reported Cu-based and Ni-based electrocatalysts. This work highlights the importance of structure and doping engineering strategies for the rational fabrication of high-performance electrocatalysts for biomass upgrading.

The carbon reduction puzzle in stock market: Evidence from China’s “Dual-Carbon Target”

ABSTRACT By analysing the ‘Dual-Carbon Target’ event in China as a quasi-experiment, we conduct an empirical research using event study method to reveal an interesting reversal phenomenon where the cumulative abnormal returns of carbon-intensive firms first fall, then grow, and eventually return to positive values. The research also reveals that the financial performance of carbon-intensive firms is not weakened by the ‘Dual-Carbon Target’, which could explain the reversal of stock returns of carbon-intensive firms. Compared with firms with less green innovation and private firms, the cumulative abnormal returns of firms with more green innovation and state-owned-firms experience a more pronounced decline in the short term. While carbon risk has been incorporated into the stock market, our results indicate that the low-carbon transition would be slow and iterative because of the current situation of high dependence on and rigid demand of fossil energy.

A hybrid deep learning framework driven by data and reaction mechanism for predicting sustainable glycolic acid production performance

AbstractSelective oxidation at low temperatures without alkali of biomass is a promising and sustainable avenue to manufacture glycolic acid (GA), a biodegradable functional material to protect the environment. However, producing glycolic acid with high selectivity and yield using the traditional research and development approach is time‐consuming and labor‐intensive. To this context, a hybrid deep learning framework driven by data and reaction mechanisms for predicting GA production was proposed, considering the lack of related reaction mechanisms in the machine learning algorithms. The proposed hybrid deep learning framework involves the kinetic reaction mechanism, catalyst properties, and reaction conditions. Results showed that the fully connected residual network exhibited superior performance (average R2 = 0.98) for the prediction of conversion rate and product yields. Then, the multi‐objective optimization and experimental verification guided the research are carried out. The experimental verification is comparable to the modeling results, with errors of less than 4% for conversion rate and GA yields. The life cycle assessment further identifies that using the optimized operating parameters, the fossil energy demand and greenhouse emissions have decreased by 2.96% and 3.00%, respectively. This work provides new insight and strategy to accelerate the engineered selective oxidation for desired GA production.

Techno-Economic Analysis of Carbon Dioxide Separation for an Innovative Energy Concept towards Low-Emission Glass Melting

The currently still high fossil energy demand is forcing the glass industry to search for innovative approaches for the reduction in CO2 emissions and the integration of renewable energy sources. In this paper, a novel power-to-methane concept is presented and discussed for this purpose. A special focus is on methods for the required CO2 capture from typical flue gases in the glass industry, which have hardly been explored to date. To close this research gap, process simulation models are developed to investigate post-combustion CO2 capture by absorption processes, followed by a techno-economic evaluation. Due to reduced flue gas volume, the designed CO2 capture plant is found to be much smaller (40 m3 absorber column volume) than absorption-based CO2 separation processes for power plants (12,560 m3 absorber column volume). As there are many options for waste heat utilization in the glass industry, the waste heat required for CO2 desorption can be generated in a particularly efficient and cost-effective way. The resulting CO2 separation costs range between 41 and 42 EUR/t CO2, depending on waste heat utilization for desorption. These costs are below the values of 50–65 EUR/t CO2 for comparable industrial applications. Despite these promising economic results, there are still some technical restrictions in terms of solvent degradation due to the high oxygen content in flue gas compositions. The results of this study point towards parametric studies for approaching these issues, such as the use of secondary and tertiary amines as solvents, or the optimization of operating conditions such as stripper pressure for further cost reductions potential.

Cost Model for Biogas and Biomethane Production in Anaerobic Digestion and Upgrading. Case Study: Castile and Leon.

The increase in pig production is a key factor in the fight against climate change. The main problem is the amount of slurry which causes environmental problems, therefore optimal management is needed. This management consists of an anaerobic digestion process in which biogas is produced and a subsequent upgrading process produces biomethane. In this study, a comparison of different biomethane production systems is completed in order to determine the optimum for each pig farm, determining that conventional upgrading systems can be used on farms with more than 11,000 pigs and, for smaller numbers of pigs, the biological upgrading system. The implementation of these technologies contributes to reducing fossil energy demand and greenhouse gas emissions by using biogas and biomethane as heat, electricity or vehicle fuel.