• Energy Research

Abstract A major challenge to commercial production of cellulosic ethanol pertains to the cost-effective breakdown of the complex and recalcitrant structure of lignocellulose into its components via pretreatment, the cost of enzymes for hydrolysis and fermentation, and the conversion rate of C5 sugars to ethanol, among others. While the industrialized and some emerging countries are gradually breaking grounds in cellulosic ethanol, most African countries have made little effort in research and development even though the continent is rich in lignocellulosic biomass. The paper estimates residues from widely available crops and municipal waste and determines their respective theoretical ethanol potential (around 22 billion litres annually). It further reviews stages involved in the production of cellulosic ethanol, focussing on processing methods that can be adapted to current situation in most African countries. The paper suggests that research and development should highlight favourable pretreatment methods such as extrusion, steaming/boiling, and chemical methods employing lime, KOH and crude glycerol (from biodiesel production), as well as the development of crude enzyme complexes from local materials. Though the falling price of enzymes is improving economic production of ethanol, advancements in heterogeneous catalytic hydrolysis will considerably favour economic production of ethanol in Africa due to the potential of recycling and reusing solid acid catalysts.

Abstract The global campaign to minimise greenhouse gas emissions and reduce fossil fuel dependency has led to the consideration of crop residue as feedstock for various bioenergy technologies. In this study, the extent to which various crop residues in the ten administrative regions of Ghana can contribute to the specific heat and electricity demands of each region was assessed. The conversion of residues from 22 crops to briquettes, biomethane and bioethanol-based electricity were examined using resource modelling to determine their potential contribution to wood fuels, Liquefied Petroleum Gas (LPG) and electricity demand respectively. The results indicate that, the Eastern Region generated the highest amount of crop residues at 2.3 Mt, mainly from cassava stalks while the Greater Accra Region generated the least amount of crop residue from the ten regions at 52.3 kt. The conversion of selected crop residues to briquettes would contribute to 53.6% of the national wood fuel demand, with Eastern and Brong Ahafo Regions recording the highest individual contributions of 27.7 and 20.5% respectively. Biomethane would contribute to 11.7% of LPG demand in all the ten regions. Electricity generated from bioethanol would supplement 91.2% of the national electricity demand. Overall, the prospects are highest for the production of electricity from bioethanol produced from crop residue to support regional energy demands.

Access to modern forms of energy continues to elude the majority of households in sub-Saharan Africa (SSA) and only about 30% of the population has access to electricity while 90% relies on traditional fuels for cooking and heating. The central question addressed in this review is whether or not SSA can provide access to modern energy services for its entire population by 2030. The review points out that efforts which succeed in integrating productive uses and income generation activities into energy access initiatives, whether based on conventional fuels or renewable energy, may well turn out to be the deciding factor if the dream of energy for all in sub-Saharan Africa is to become a reality in the foreseeable future.

Anaerobic digestion (AD) can bring benefits in terms of effective management of organic waste, recovery of nutrients and energy recovery, and is consistent with circular economy principles. AD has been promoted and implemented worldwide, but at widely differing scales, influenced by the availability and location of feedstocks. In developing countries, feedstock arises from small- to medium-scale agriculture and agro-processing operations, as well as from household and municipal waste. Biogas produced from residues from agro-processing facilities may be used for on-site heat and power, but the lack of a gas and electricity grid infrastructure can limit opportunities to distribute gas or generated electricity to wider users. This paper presents the findings of the first study to consider novel technologies for small-scale and low-cost biogas clean-up into biomethane, and compression into small bottles, suitable as a clean cooking fuel. The paper reports on the initial evaluation of biomethane for cooking in Ghana and Uganda.

Abstract As Ghana's economy grows, the choice of future energy paths and policies in the coming years will have a significant influence on its energy security. A Renewable Energy Act approved in 2011 seeks to encourage the influx of renewable energy sources in Ghana's energy mix. The new legal framework combined with increasing demand for energy has created an opportunity for dramatic changes in the way energy is generated in Ghana. However, the impending changes and their implication remain uncertain. This paper examines the extent to which future energy scenarios in Ghana could rely on energy from biomass sources, through the production of biogas, liquid biofuels and electricity. Analysis was based on moderate and high use of bioenergy for transportation, electricity generation and residential fuel using the LEAP (Long-range Energy Alternatives Planning) model. Results obtained indicate that introducing bioenergy to the energy mix could reduce GHG (greenhouse gas) emissions by about 6 million tonnes CO2e by 2030, equivalent to a 14% reduction in a business-as-usual scenario. This paper advocates the use of second generation ethanol for transport, to the extent that it is economically exploitable. Resorting to first generation ethanol would require the allocation of over 580,000 ha of agricultural land for ethanol production.

Nature Energy, 7 (11) ISSN:2058-7546

Crop residues are common in rural Ghana due to the predominant role agriculture plays in livelihood activities in these communities. In this paper we investigate the prospects of exploiting agricultural crop residues for rural development in Ghana through bioenergy schemes. A theoretical energy potential of 623.84 PJ per year, which is equivalent to 19,781 MW was estimated using crop production data from the Food and Agricultural Organization of the United Nations and residue-to-product ratios. Ghana has a total installed generation capacity of 4577 MW which is four times less the energy potential of crop residues in the country. Cocoa pod husks were identified as important biomass resources for energy generation as they are currently wasted. To further assess the energy potential of cocoa pod husks, different cocoa pod husks samples were collected across the six cocoa growing regions in Ghana and thermo-chemically characterised using proximate and ultimate analysis. The low levels of nitrogen and sulphur observed, together with the high heating value, suggest that cocoa pod husks and for that matter crop residues are eco-friendly feedstock that can be used to power rural communities in Ghana.

In the absence of the widespread distribution of modern cooking fuels in developing countries, efforts are being made to utilise biomass residues which abound in most of these countries. This is intended to replace portions of firewood and charcoal and thereby reduce the cutting down of forests for fuel purposes. Briquettes from agro-residues have therefore been promoted as a better replacement to firewood and charcoals for heating, cooking and other industrial applications in both urban and rural communities. This study sought to assess the physico-chemical properties of charcoal briquettes produced in Ghana and also establish demand for and willingness of potential users to substitute charcoal and firewood with a charcoal briquette. A laboratory experiment was conducted to determine the physico-chemical characteristics of the briquettes. This was done prior to the distribution of the briquette to potential users to collaborate their views or otherwise on the handling and burning characteristics of the charcoal briquette. A survey was undertaken a week later using questionnaires to access the willingness of the potential users to use the briquettes. Sixty respondents were purposively selected from households and the hospitality industry for the survey. Results of the physico-chemical assessment of the briquettes were as follows: length (75 to 120 mm), moisture content (5.7% dry basis), density (1.1 g/cm3), ash content (2.6%), fixed carbon (20.7%), volatile matter (71%) and calorific value (4,820 kcal/kg). Responses from the survey indicated that the briquette is easy to ignite, has a long burning time and has good heat output. Respondents also observed that the briquettes did not give off sparks and had less smoke and ash content as compared to the regular charcoal they often used. Finally, 93% of the respondents indicated their willingness to use the briquettes if the price was comparable to charcoal.