Mirjam Röder

Importance of non-CO2 emissions in carbon management

Background: GHG budgets highlight a need for urgency, yet analyses are often CO2-focused, with less attention paid to non-CO2. Results: In this paper, scenarios are used to explore non-CO2 drivers and barriers to their mitigation, drawing out implications for CO2 management. Results suggest that even optimistic technological and consumption-related developments lead to on-going increases in global N2O, largely to improve food security within a changing climate. This contrasts with existing analysis, where lower levels of N2O by 2050 are projected. Conclusions: As avoiding ‘2ｰC’ limits the emissions budget, constraints on reducing non-CO2 add pressure to energy system decarbonization. Overlooking how a changing climate and rising consumption restricts efforts to curb non-CO2 will result in policies aiming to avoid 2ｰC falling short of the mark.

Electricity From North American Forest Residues

Abstract Electricity from biomass feedstocks is often considered as a sustainable Greenhouse gas reduction option compared to electricity generated from fossil fuels. Past research has shown that significant emission reduction from wood pellets is possible, but that these are also related to large uncertainties. This chapter describes supply chains emissions and related uncertainties of electricity generated from wood pellets from forest and sawmill residues through lifecycle assessment. The results indicate that GHG reductions of up to 83% can be reached compared to coal-based electricity. Nevertheless, considering parameters like feedstock drying, storage, and dry matter losses shows strong variations of the emission profile. To avoid potentially higher GHG emissions from large-scale bioelectricity compared to coal, good practice and storage management as well as the use of renewable energy for energy-intense supply chain processes, like drying, are necessary.

Waste wood as bioenergy feedstock. Climate change impacts and related emission uncertainties from waste wood based energy systems in the UK

Considering the urgent need to shift to low carbon energy carriers, waste wood resources could provide an alternative energy feedstock and at the same time reduce emissions from landfill. This research examines the climate change impacts and related emission uncertainties of waste wood based energy. For this, different grades of waste wood and energy application have been investigated using lifecycle assessment. Sensitivity analysis has then been applied for supply chain processes and feedstock properties for the main emission contributing categories: transport, processing, pelletizing, urea resin fraction and related N2O formation. The results show, depending on the waste wood grade, the conversion option, scale and the related reference case, that emission reductions of up to 91% are possible for non-treated wood waste. Compared to this, energy from treated wood waste with low contamination can achieve up to 83% emission savings, similar to untreated waste wood pellets, but in some cases emissions from waste wood based energy can exceed the ones of the fossil fuel reference - in the worst case by 126%. Emission reductions from highly contaminated feedstocks are largest when replacing electricity from large-scale coal and landfill. The highest emission uncertainties are related to the woods resin fraction and N2O formation during combustion and, pelletizing. Comparing wood processing with diesel and electricity powered equipment also generated high variations in the results, while emission variations related to transport are relatively small. Using treated waste wood as a bioenergy feedstock can be a valid option to reduce emissions from energy production but this is only realisable if coal and landfill gas are replaced. To achieve meaningful emission reduction in line with national and international climate change targets, pre-treatment of waste wood would be required to reduce components that form N2O during the energy conversion.