A comparative life cycle assessment (LCA) of impregnated wooden sleepers is presented in this report. The included impregnation oils are linseed oil and creosote, and the environmental aspects considered here are climate change, ecotoxicity, human toxicity and the use of fossil resources.
The results of the LCA indicate that the carbon footprint of the linseed oil sleeper is equal to or higher than the carbon footprint of creosote. The main contributors to the linseed oil’s carbon footprint are emissions of nitrous oxide and carbon dioxide from the use of fertilizers on the farmland and carbon dioxide emissions from fossil fuels used in tractors, lorries and for the production of steam and electricity used in the production process.
Considering the ecotoxicity and human toxicity, the results indicate that the creosote sleeper performs worse than the linseed oil sleeper, which might be expected. However, depending on how the environmental burdens of linseed oil, linseed cake and straw are allocated between them (mass or economical allocation) the results for the linseed oil sleeper vary to a large extent.
The results are associated with some uncertainties: for example, no full-scale production plant for linseed oil sleepers exist today meaning that the input data to some extents are based on estimations. To reduce the carbon footprint of sleepers impregnated with linseed oil, a few measures were identified.
For example, by changing from diesel in tractors and trucks in the agriculture of linseed, as well as natural gas in the production process to renewable fuels. The carbon footprint can also be decreased by reusing the sleepers after their use phase.
2023.