Sustainable building and CO2 emissions: analysis of the transport of sand in Tijuana and Tecate, B.C.

Abstract

The sands are the second most resources extracted and traded by volume after water and outperform fossil fuels and biomass. Currently, 50 billion tons are extracted per year, or an average of 18 kg per person per day [1]. Although the life cycle approach of materials requires that the environmental costs of the construction process be quantified at all stages, the efforts of UN agencies and international organizations to account for CO₂ emissions have not considered the contribution of GHGs during the transport of materials such as gravel and sand and, if they do, the data is aggregated in other topics. More than 60% of the aggregates produced in Baja California come from the Las Palmas river that runs along the municipalities of Tijuana and Tecate, B.C.  Hence the regional environmental effects are important. This study aimed to estimate CO₂ emissions during sand transport using the IPCC level 1 method and vehicular counting techniques. Sand transportation from the extraction zone, in the Las Palmas river, to a transfer station located in the Alamar river was analyzed. Sixteen types of vehicles were identified. For a route of 75 km, an emission of 77.7 kg of CO₂ was calculated. Emissions from 0.8 to 8.7 kg of CO₂ were found per ton of sand transported; or its equivalent volume of 1.3 to 13.9 kg / m3; Therefore, the most efficient vehicles in terms of emissions were those with the greatest load capacity. The removal of sands from riverbeds, in addition to generating water impacts, also contributes to climate change due to the cumulative impact of CO₂ emissions. This emphasizes the need for policies to promote more efficient means of transport for the transfer of aggregates.