Building with biomass using tropical timber as a negative emissions technology (NET): Sustainability assessment, comparison with other bio-based NETs and their potential in Malaysia

Abstract

Building with biomass is a negative emissions technology (NET) that can be used to store CO₂ in the built environment. As countries seek scalable climate solutions, understanding the viability of such approaches in developing nations is increasingly critical. This paper is the first to determine the environmental impacts and economic feasibility of building with biomass using timber, focusing on the residential housing sector in a developing country such as Malaysia. Four tropical hardwood species are considered: resak, keruing, sesenduk and rubber. The environmental assessment comprises 18 life cycle assessment impacts and the economic assessment focuses on life cycle costs. The system boundary includes all activities from cradle to grave, i.e. from timber production to house demolition. All timber species result in net-negative global warming potential (GWP), ranging from −473 to −736 kg CO₂ eq./t CO₂ removed without the credits for energy savings in the use stage relative to concrete houses dominant in Malaysia. With the credits, the savings in the emissions are around 30–60 % greater (−745 to −973 kg CO₂ eq./t CO₂ removed). Resak and rubber perform best overall, while sesenduk ranks lowest across most impacts. The life cycle costs are estimated at US$338–823/t CO₂ removed across the scenarios and timber types, with resak being the least and keruing the most expensive option. Assuming all houses are built from one type of timber could remove from 47 Mt CO₂ (sesenduk) to 98 Mt CO₂ (resak) over 50 years, reducing 4–8 % of the country's agricultural emissions annually at the cost from US$38 bn (rubber) to US$83 bn (keruing). Using an optimal combination of the four timber types would remove 89.12 Mt CO₂ over 50 years at a total cost of US$53.5 bn. However, in comparison with other bio-based NETs, building with biomass is the least sustainable option. Reforestation is the best alternative, removing 153–587 Mt CO₂ at a total cost of −US$10.2 bn (profit) to US$5.8 bn over 50 years, followed by bioenergy with carbon capture and storage (BECCS) with 840 Mt CO₂ and US$63.6 bn over 30 years and biochar with 248 Mt CO₂ and US$21.5 bn over 20 years. Utilising the country's available resources with an optimal mix of the four bio-NETs could remove 27.5 Mt CO₂ per year (9.5 % of Malaysia's annual emissions) at a cost of US$1.92 bn/yr. Over the lifetime of the NETs, this would amount to a total CO₂ removal of 930 Mt at a cost of US$56 bn. These results can be used to inform policy and other decision makers on the optimal deployment of bio-based NETs in Malaysia.