Fossil Fuel-derived Energy Research Articles

Design and Construction of an Anaerobic Digester for the Ingestion of Waste from the Cocoa Industry in Nigeria

The Anaerobic Digester designed and constructed for waste ingestion from the Nigerian cocoa industry aims to harness abundant renewable energy from crop residues like cocoa rinds and groundnuts. This study evaluates the biogas potential of these sources in contributing to the country's overall energy needs, emphasizing the imperative for environmental sustainability. Focusing on reducing fossil energy consumption, greenhouse gas emissions, and minimizing environmental impact, the project advocates for a shift towards biogas for day-to-day energy requirements, presenting direct cost savings. The utilization of fossil fuel-derived energy is known to contribute to temperature increase, greenhouse gas emissions, noise pollution, and ground-level air pollution, all of which can be mitigated through biogas utilization. This initiative involves the design and construction of a 0.24m<sup>3</sup> pilot plastic fossil plant for biogas generation, aiming to "green" various applications, including domestic and industrial usage as well as transportation. The digester, constructed from high-density polyethylene (HDPE) plastic, demonstrates leak-free operation, further supporting its potential for long-term sustainability. Results from a 28-day retention period show a cumulative biogas yield, with a daily assessment indicating a gas yield of 0.0496 m<sup>3</sup> on the 12th day. The study highlights the positive and negative influences of temperature inequality gradients ≥34°C≤38°C on biogas production. This comprehensive research contributes valuable insights for the sustainable management of waste and the utilization of biogas as a viable alternative energy source.

Mining the brine

The era of fossil fuel-derived energy is drawing to a close. Electricity generation via renewable sources is a promising candidate to bridge the gap to a low-carbon future (Fig. 1), but it has created and will continue to generate an unprecedented demand for metals, such as copper, lithium and nickel. A global-scale transition to an […]

Long term relationship between food, energy and water inflation in South Africa

The food-energy-water (FEW) nexus provides leeway into the lateral transmission of price volatilities within the sectors. The problem is that any inflationary price tendencies in one of the FEW sectors will have direct and indirect effect on the others. The objective of the study was to ascertain the relationship between inflation in food, energy and water, and determine whether there were spill-overs, in South Africa. Monthly consumer price indices for food, energy and water for the period spanning from January, 2002 to December, 2020, were used. Parsimonious vector autoregressive (VAR) model was used in data analysis. The study found that prior to 2013, inflation rate was higher for food relative to water and energy, respectively. After 2017, water had a higher inflation rate relative to energy and food, respectively. Furthermore, energy inflation had positive impact on both water and food inflation, whilst water inflation also had positive impact on food inflation. The study concludes that there is a nexus in the lateral inflation between food, energy and water. Recommendations include building resilience within the nexus through decoupling food and other sectors from fossil fuel-derived energy. It is needed to strike a balance in biofuel and energy production policy to foster complementarities. Operational efficiencies within the sectors also need to be fostered.

Microbial fuel cell: Bio-energy production from Nigerian corn starch wastewater using iron electrodes

The emerging increasing issues with the use of fossil fuel-derived energy resources and related challenges like pollution, global warming and climate change are boosters for adoption of renewable energy resource. Energy is a key criteria for socio-economic development of any nation, thus the search for an environmentally-friendly solution. Microbial Fuel Cell (MFC) is a promising method for the generation of green energy from waste. This study investigated the use of Nigerian corn starch wastewater as substrate for a dual-chamber MFC set-up. Iron electrodes were used for electron transfer. Up to 1.43 mA current, 0.97 V, 8.10 mA/cm2 maximum current density and 7.7 mW/cm2 maximum power density was achieved in 9 days of the experiment. The results present a relatively improved version when compared to previous studies. The experiment proves a promising alternative energy source for off-grid power solution, during Covid-19 and post-Covid-19 era.

Anthropogenic energy and carbon flows through Canada’s agri-food system: Reframing climate change solutions

Abstract Greenhouse gas accounting for agricultural systems consider methane and nitrous oxide emissions, carbon emissions from liming and urea use, as well as carbon stock changes, but it ignores gross flows of bio-based energy and carbon. This study compiled data for Canada’s agri-food system over the 2010-13 period, from food supply and disposition to crop processing, animal production, and crop/pasture production. The data were converted to units of energy and carbon, tracked through the agri-food system and compared in scale and conversion efficiency with Canadian crude oil recovery to the production of refined petroleum products. Results showed domestic photosynthesis-derived energy and carbon flow equivalent to 75% and 98%, respectively, of the fossil fuel-derived energy and carbon in the crude oil recovered in Canada. This magnitude is substantial since Canada is a nation with high per capita oil demand that exports over 50% of its own production. Only 14% of the agri-food energy and carbon, respectively, emerged in agri-food products, compared to 91% of the energy and carbon in crude oil that resulted in refined petroleum products. The low conversion efficiency of the agri-food system derived, in part, from 40% of bio-based energy and carbon being diverted to crop and animal residues or waste. Per unit of energy in end products, the other energy inputs (e.g. electricity, fuels) needed to support the agri-food system were 5.3-folds higher in the agri-food system than in the crude oil to products system. This study highlights the need to develop strategies to better utilize the energy and carbon flows of the agri-food system, thereby reducing fossil energy use and greenhouse gas emissions associated with human activities.

Effect of CO2 and metal-rich waste water on bioproduct potential of the diazotrophic freshwater cyanobacterium, Tolypothrix sp.

Continued economic growth is reliant on stable, affordable energy, requiring at present fossil fuel-derived energy production. Coal-fired power stations produce metal-rich but macro-nutrient-poor waste waters and emit flue gas, containing ∼10% CO2. Algae and cyanobacteria remediate metals and CO2, but use of N2-fixing (diazotrophic) cyanobacteria can reduce nitrogen-fertilization costs. The resulting biomass represents a promising source for biofuel and bio-product development. This study investigated the effect of CO2- and trace metals on growth performance, biochemical profiles and metal content of the freshwater diazotrophic cyanobacterium Tolypothrix sp. to assess bioproduct potential. Aerated 2 L batch cultures were grown in simulated ash-dam water (SADW) and BG11 without nitrogen (BG11(-N) controls). Supplied air was supplemented with either 15% CO2 or not (non-CO2 controls). CO2 supplementation resulted in 2.4 and 3.3-fold higher biomass productivities and 1.3 and 1.2-fold higher phycocyanin and phycoerythrin contents, whilst metals (media) had no effect. Al, Cu, Ni and V were more efficiently removed (50–90%) with CO2-addition, while As, Mo, Se and Sr removal was higher (30–87%) for non-CO2 controls. No significant effect on Zn and Fe removal was evident. Calculated biomass metal concentrations, at quantities required to meet N-requirements of wheat, suggests no metal toxicity when applied as a mineral-nitrogen biofertilizer. With a carbohydrate content of 50%, the biomass is also suitable for bioethanol production. In summary, Tolypothrix sp. raised in ash dam waste water supplemented with flue gas CO2 could yield high-value phycobiliproteins, bioethanol or biogas, and mineral-rich nitrogen fertilizer which would offset remediation costs and improve agricultural productivity.

Bio-Refining of Carbohydrate-Rich Food Waste for Biofuels

The global dependence on finite fossil fuel-derived energy is of serious concern given the predicted population increase. Over the past decades, bio-refining of woody biomass has received much attention, but data on food waste refining are sorely lacking, despite annual and global deposition of 1.3 billion tons in landfills. In addition to negative environmental impacts, this represents a squandering of valuable energy, water and nutrient resources. The potential of carbohydrate-rich food waste (CRFW) for biofuel (by Rhodotorulla glutinis fermentation) and biogas production (by calculating theoretical methane yield) was therefore investigated using a novel integrated bio-refinery approach. In this approach, hydrolyzed CRFW from three different conditions was used for Rhodotorulla glutinis cultivation to produce biolipids, whilst residual solids after hydrolysis were characterized for methane recovery potential via anaerobic digestion. Initially, CRFW was hydrolysed using thermal- (Th), chemical- (Ch) and Th-Ch combined hydrolysis (TCh), with the CRFW-leachate serving as a control (Pcon). Excessive foaming led to the loss of TCh cultures, while day-7 biomass yields were similar (3.4–3.6 g dry weight (DW) L−1) for the remaining treatments. Total fatty acid methyl ester (FAME) content of R. glutinis cultivated on CRFW hydrolysates were relatively low (~6.5%) but quality parameters (i.e., cetane number, density, viscosity and higher heating values) of biomass extracted biodiesel complied with ASTM standards. Despite low theoretical RS-derived methane potential, further research under optimised and scaled conditions will reveal the potential of this approach for the bio-refining of CRFW for energy recovery and value-added co-product production.

An overview of climate and crop yield in closed greenhouses

SummaryThe closed greenhouse is a recent innovation in the horticulture industry. Cooling by ventilation is replaced partly (in semi-closed greenhouses) or completely (in closed greenhouses) by mechanical cooling. Excess solar energy is collected and stored to be reused to heat the greenhouse. In temperate climates, this concept combines improved crop production with energy savings. This paper presents an overview of climate, crop growth and development, and crop yield in closed and semi-closed greenhouses. The technical principles of a closed greenhouse are described and the macroclimate and microclimate arising from this are studied. The consequences of the typical growth conditions found in closed greenhouses for crop physiology and crop yield are examined. Finally, the experiences of commercial growers are presented. In temperate climates, closed greenhouses can reduce the use of fossil fuel-derived energy by 25 – 35%, compared with open greenhouses. With high global radiation, the climate in closed greenhouses is characterised by high CO2 concentrations, high air humidity, improved temperature control, and a vertical temperature gradient. An annual increase in production of 10 – 20% is realistic, with reduced amounts of supplied CO2. The yield increase is primarily obtained through increased rates of photosynthesis due to the higher CO2 concentrations in closed greenhouses. To introduce this innovation into practice, knowledge transfer was a key factor for its implementation and the realisation of increased production levels. Future trends will require minimising the use of fossil fuels and increasing the level of control of the production process. Closed and semi-closed greenhouses fit seamlessly into this trend as they allow for a more controlled climate and higher levels of production, combined with savings in fossil fuel use.

Soil health in agricultural systems

Soil health is presented as an integrative property that reflects the capacity of soil to respond to agricultural intervention, so that it continues to support both the agricultural production and the provision of other ecosystem services. The major challenge within sustainable soil management is to conserve ecosystem service delivery while optimizing agricultural yields. It is proposed that soil health is dependent on the maintenance of four major functions: carbon transformations; nutrient cycles; soil structure maintenance; and the regulation of pests and diseases. Each of these functions is manifested as an aggregate of a variety of biological processes provided by a diversity of interacting soil organisms under the influence of the abiotic soil environment. Analysis of current models of the soil community under the impact of agricultural interventions (particularly those entailing substitution of biological processes with fossil fuel-derived energy or inputs) confirms the highly integrative pattern of interactions within each of these functions and leads to the conclusion that measurement of individual groups of organisms, processes or soil properties does not suffice to indicate the state of the soil health. A further conclusion is that quantifying the flow of energy and carbon between functions is an essential but non-trivial task for the assessment and management of soil health.

Renewable Biomethane From Land and Ocean Energy Crops and Organic Wastes

Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This could replace fossil fuel-derived energy and reduce its environmental impacts, including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs with other biomass energy forms including heat, synthesis gases, and ethanol. The objective of this paper is to review the results and conclusions of research on biomass energy conducted under the sponsorship of the gas industry with periodic co-funding from other agencies. The scope of this program was to determine the technical and economic feasibility of production of substitute natural gas (SNG) from marine and terrestrial biomass and organic wastes using anaerobic digestion as a conversion process. This work began in 1968 and continued until about 1990, ending as a result of low energy prices in the U.S. and reduced emphasis on renewable energy. For each of these feedstock categories, growth or collection (in the case of wastes), harvesting, conversion by anaerobic digestion, and systems and economic analysis were addressed. More recently the potential use of anaerobic digestion for stabilization and recovery of nutrients from solid wastes during space missions was studied with funding from NASA. The application of this process for that function as well as treatment of wastewater and waste gases generated during space missions is addressed.

Renewable energy: a response to climate change

“We recognize the importance of renewable energy for sustainable development, diversification of energy supply, and preservation of the environment. We will ensure that renewable energy sources are adequately considered in our national plans and encourage others to do so as well. We encourage continuing research and investment in renewable energy technology, throughout the world”. Communique from the G8 Leaders’ Summit, Genoa, July 2001. The Third Assessment Report of the IPCC confirmed that the Earth’s climate is changing as a result of human activities, particularly from energy use, and that further change is inevitable. Natural ecosystems are already adapting to change, some are under threat, and it is evident that human health and habitats will be affected world-wide. Such climate changes could also affect the present supplies of renewable energy sources and the performance and reliability of the conversion technologies. This paper concentrates on the reduction of carbon dioxide emissions and the role that the global renewable energy industry might play in this regard. (The five other major greenhouse gases are given less emphasis here.) The paper compares the costs of renewable energy systems with fossil fuel-derived energy services and considers how placing a value on carbon emissions will help provide convergence. The move towards a de-carbonised world, driven partly by climate change science and partly by the business opportunities it offers, will need to occur sooner rather than later if an acceptable stabilisation level of atmospheric carbon dioxide is to be achieved. Government policy decisions made now will determine the sort of future world we wish our children to inherit. The renewable energy era has begun.

Renewable methane from anaerobic digestion of biomass

Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This would replace fossil fuel-derived energy and reduce environmental impacts including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through emission regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs to other biomass energy forms including heat, synthesis gases, and ethanol.