Assessment of energy and exergy efficiencies and renewability of black tea, instant tea and ice tea production and waste valorization processes

Abstract

Cumulative degree of perfection (CDP), cumulative carbon dioxide emission (CCO2E) and renewability indicator (RI) are employed as tools to assess sustainability of packaged black tea, instant tea and ice tea production processes and valorization of their waste. The black tea production process, when there is no waste, had the highest CDP and the renewability indicator RI, with CDP =0.425 and RI = −1.35. The CDP was 0.013 and RI was −31.30 with the instant, and CDP =0, RI = −610,668 with the ice tea production processes. When activated carbon, hydrogen and adsorbent material were produced from the waste of the instant tea, the CDP increased to 0.087, 0.035 and 0.172, respectively; in these cases, the RI increased to −10.53, −27.90 and −4.83, respectively. The negative RI values indicate non-renewability of the processes. Increase in the positive CDP and the decrease in the negative RI values show that when adsorbent material production from waste was done together with instant tea production, substantial improvement may be achieved. Similar improvements may also be achieved in the case of ice tea production when the waste is subject to valorization.