Life cycle environmental and economic performance of biochar compared with activated carbon: A meta-analysis

Abstract

As the commercial production and distribution of biochar continues to grow internationally, and its applications diversifying from its early uses as soil amendment, it is important to study the environmental impacts and economic performance of biochar in comparison to activated carbon in order to assess its value. The goal of the study was to assess, through a meta-analysis, the environmental and economic performance of biochar in comparison to activated carbon under an equivalent functional unit to adsorb heavy metals. More than 80 data points on adsorption capacity of biochar and activated carbon were identified through literature, which were statistically analyzed as part of the study. Biochar was found to have lower energy demand and global warming potential impact than activated carbon, where average energy demands were calculated as 6.1 MJ/kg and 97 MJ/kg and average greenhouse gas emissions calculated as-0.9 kg CO 2 eq/kg and 6.6 kg CO 2 eq/kg for biochar and activated carbon, respectively. When adsorption of heavy metals were used as the functional unit during analysis, results indicate that there is typically an order of magnitude difference between the two materials, where biochar was found to have lower environmental 1 10 100 1000 10000 Cadmium Copper Zinc Lead Chromium Adsorption cost, US $/kg contaminant Biochar Activated carbon 2 impacts. The environmental impact resulting from long distance transportation of biochar would not overturn this conclusion. The adsorption cost of biochar was lower than activated carbon to remove chromium and zinc with a 95% confidence. Adsorption cost for lead and copper were found to be comparable, and therefore the specific type of biochar and its price could shift results both ways. There is evidence that biochar, if engineered correctly for the task, could be at least as effective as activated carbon and at a lower cost.

Amyloid Fibrils Aerogel for Sustainable Removal of Organic Contaminants from Water

“…The production of 1 kg of activated carbon requires 97 MJ of energy (high activation temperature above 500 °C) and results in 6.6 kg carbon dioxide equivalent emission in the atmosphere. [15] Thus, it is necessary to develop effective and inexpensive new technologies to remove organics from water sources.…”

“…Although activated carbon is a well‑known adsorbent for the removal of organic pollutants from water, its production is no longer considered sustainable due to high‑energy demand and greenhouse emissions. The production of 1 kg of activated carbon requires 97 MJ of energy (high activation temperature above 500 °C) and results in 6.6 kg carbon dioxide equivalent emission in the atmosphere . Thus, it is necessary to develop effective and inexpensive new technologies to remove organics from water sources.…”

Biochar-augmented biofilters to improve pollutant removal from stormwater – can they improve receiving water quality?

“…Biochar costs vary widely, depending on the feedstock, transport, pyrolysis operation, and other factors, but are estimated to range from $350 to $18 000 per metric ton. 130,131 The current cost of biochar is significant compared to construction sand, which is typically used as biofilter media and cost about $8.6 per metric ton in 2015. 132 However, the incremental cost of adding biochar may be worthwhile when also considering its water quality benefits.…”

Analysis of environmental impact of activated carbon production from wood waste

“…There are only few studies on LCA of the AC production process. Alhashimi and Aktas [26] analyzed environmental impact for biochar comparing with AC by LCA methodology. The study reported that average Greenhouse Gases (GHGs) emissions were calculated to be -0.9 kg CO 2 -eq.…”