TITLE:
Energy-Exergy Analysis and Carbon (IV) Oxide Emission of an Aluminium Extrusion Plant in Nigeria
AUTHORS:
Mufutau Adekojo Waheed, Peter Olaitan Aiyedun, Wasiu Oyediran Adedeji, Adekunle Adedapo Obisanya, Semiu Taiwo Amosun, Adeniyi Oluwole Adesina
KEYWORDS:
Exergy, Energy, Carbon (IV) Oxide, Emission, Pollution
JOURNAL NAME:
Engineering,
Vol.9 No.12,
December
29,
2017
ABSTRACT: Energy security, cost of production and environmental constraints have necessitated the need for proper energy utilisation in the manufacturing industries. This work analysed energy and production data from an aluminium extrusion plant in Lagos, Nigeria for energy efficiency, exergy efficiency (or processefficiency), energy cost per unit of production, CO2 emission and pollutionrateindex. The input-output energy analysis method was used to estimate theembodied energy intensity. The pollution rate, energetic and exergetic efficiencies were estimated from the exergy analysis. The CO2 emission was estimatedfrom IPCC guideline on greenhouse inventories and the energy cost of unitproduce was estimated from energy cost accounting method. The five-year average thermal and electrical utilisation ratio was 45/55, which deviated from the 70:30 of the global best practices. The embodied energy intensity for the five years’ ranges between 2.31 - 162.3 GJ/t which is in excess of the recommendedrange of (2.9 - 3.2 GJ/t). The mean energy efficiency for the five year was 79.4% and the mean exergetic efficiency was 57.8% indicating that production was wellmanaged (>50%) with energy wastages very high in boiler energy conversion. The total energy used was 16 MJ and CO2 emitted is 1.01 × 1011 g during the study period. The average pollution rate index for the plant was 0.8695 indicating that the plant is negatively impacting the environment due to technological limitation of the energy conversion process employed in the manufacturing plant. The study reveals a distortion of the recommended best practice in energy balance ratio which accounted for the high average cost of production (N 4418.3/t); process efficiency was generally low thereby negatively affecting industrial output for the company.