The potential of coffee stems gasification to provide bioenergy for coffee farms:a case study in the Colombian coffee sector

The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas

The potential of coffee stems gasification to provide bioenergy for coffee farms: a case study in the Colombian coffee sector

From Springer Nature via Jisc Publications RouterHistory: received 2019-04-24, rev-recd 2019-07-01, registration 2019-07-15, accepted 2019-07-15, pub-electronic 2019-08-03, online 2019-08-03, pub-print 2020-12Publication status: PublishedFunder: Fondo de CTeI del Sistema General de Regalías del Departamento del Atlántico; Grant(s): Doctoral scholarship call 673 of 2014 “Formación de Capital Humano de Alto Nivel para el Departamento del Atlántico”Abstract: The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas

Challenges to the use of BECCS as a keystone technology in pursuit of 1.5⁰C

Biomass energy with carbon capture and storage (BECCS) is represented in many integrated assessment models as a keystone technology in delivering the Paris Agreement on climate change. This paper explores six key challenges in relation to large scale BECCS deployment and considers ways to address these challenges. Research needs to consider how BECCS fits in the context of other mitigation approaches, how it can be accommodated within existing policy drivers and goals, identify where it fits within the wider socioeconomic landscape, and ensure that genuine net negative emissions can be delivered on a global scale

Sustainability of bioenergy – mapping the risks and benefits to inform future bioenergy systems

Bioenergy is widely included in energy strategies for its GHG mitigation potential. Bioenergy technologies will likely have to be deployed at scale to meet decarbonisation targets, and consequently biomass will have to be increasingly grown/mobilised. Sustainability risks associated with bioenergy may intensify with increasing deployment and where feedstocks are sourced through international trade. This research applies the Bioeconomy Sustainability Indicator Model (BSIM) to map and analyse the performance of bioenergy across 126 sustainability issues, evaluating 16 bioenergy case studies that reflect the breadth of biomass resources, technologies, energy vectors and bio-products. The research finds common trends in sustainability performance across projects that can inform bioenergy policy and decision making. Potential sustainability benefits are identified for People (jobs, skills, income, energy access); for Development (economy, energy, land utilisation); for Natural Systems (soil, heavy metals), and; for Climate Change (emissions, fuels). Also, consistent trends of sustainability risks where focus is required to ensure the viability of bioenergy projects, including for infrastructure, feedstock mobilisation, techno-economics and carbon stocks. Emission mitigation may be a primary objective for bioenergy, this research finds bioenergy projects can provide potential benefits far beyond emissions - there is an argument for supporting projects based on the ecosystem services and/or economic stimulation they may deliver. Also given the broad dynamics and characteristics of bioenergy projects, a rigid approach of assessing sustainability may be incompatible. Awarding ‘credit’ across a broader range of sustainability indicators in addition to requiring minimum performances in key areas, may be more effective at ensuring bioenergy sustainability

Comparison of two different vertical column photobioreactors for the cultivation of Nannochloropsis sp

A photobioreactor (PBR) for microalgae culture is a highly efficient system for biomass production. In the present study, the performance of an airlift (ALR) (with a centric-tube column) and a bubble column (BC) photobioreactors were compared considering Nannochloropsis sp. growth. The experiments were carried out keeping average light intensity, temperature, volume culture, and CO2 supply constant, while cell concentration and pH level were measured and examined. Furthermore, a computational fluid dynamics (CFD) simulation in cfx, ansys 11.0, was developed using a multiphase flow model with an Eulerian approach to evaluate the hydrodynamic behavior of both systems. The results showed that a higher cell concentration (375 × 105 cell/ml) was obtained in the airlift PBR yielding a better growth rate than the bubble column PBR. In terms of hydrodynamic performance, the existence of the centric-tube in the airlift system shows a well-defined flow pattern, better light distribution cycle, and more effective mixing. These hydrodynamic characteristic of the airlift PBR may allow a better yield for the microalgae biomass production.</jats:p