Methane from livestock is a significant source of greenhouse gas emissions. Under the UN Framework Convention on Climate Change (UNFCCC), Annex I countries’ National Inventories report emissions from cattle as enteric or from manure management at ratios of between 3:1 and 9:1 depending on country and cattle type. Field research generally supports the inventories’ assumptions about enteric emissions, but these ratios have focused interest on enteric emissions and diverted attention away from those from manure management. Official calculations about manure management emissions factors are more varied than those for enteric emissions and evidence from field measurements suggests inventories may be underestimating manure management emissions especially in the dairy sector. This paper has three objectives. First, it reviews the science underpinning the international framework for estimating methane emissions from manure management. Second, it presents data from two dairy farms in south-west England where measured emissions of methane from slurry storage facilities are found to be four to five times greater than the assumptions in the UK’s inventory. If these measurements were representative of the UK, the implication is that total methane emissions from the UK dairy herd would be over 40% greater than the level reported to the UNFCCC and the proportion of total methane emissions from dairy cows arising from manure management would be almost a half rather than less than a quarter. Finally, the paper assesses the potential value if methane were captured from slurry storage facilities. Its value as a biogas is estimated to be £500 million per year for the UK dairy industry (at forecourt diesel prices). The paper concludes that the scale of emissions and the potential economic value of lost biogas are sufficient to warrant urgent research and action to reduce emissions from manure management with the beneficial prospect that a valuable new income stream for farm businesses could also be realised.

In an era of rapidly increasing vehicle electrification, the gasoline engine remains a vital part of the passenger car powertrain portfolio. Lean-burn combustion is a formidable means for reducing the CO₂ emissions of gasoline engines but demands the use of sophisticated emissions control. A 2.0 litre turbocharged direct-injection gasoline engine has been developed with a lean homogeneous combustion system matched to a robust lean and stoichiometric-capable exhaust aftertreatment. The aftertreatment system includes an SCR system and a GPF with filtration down to 10 nm particle size. The engine is equipped with a continuously variable valve-lift system, high-tumble ports and a high-energy ignition system; the boosting system comprises a variable geometry turbocharger and a 48 V electrical supercharger. The work reported formed part of the PaREGEn (Particle Reduced, Efficient Gasoline Engines) project under the Horizon 2020 framework programme. In this project, further development of gasoline engines as used in mid to premium-sized cars was undertaken, with the objective to reduce CO₂ emissions by 15% under Euro 6d RDE (Real Driving Emissions) legislation and with particle number emissions measured down to 10 nm. This paper will give a detailed treatment of the multi-cylinder engine and vehicle development undertaken. The engine delivered BSFC benefits exceeding 10% and a peak brake thermal efficiency of 42%, while the vehicle demonstrated a NO_x conformity factor below 1.0 in independent RDE tests.

Decarbonising heavy-duty trucks is challenging due to high journey power and energy requirements. With a growing fleet of commercial vehicles in the UK, biomethane can provide significant reductions in greenhouse gas (GHG) emissions compared to fossil diesel. Methane is a potent GHG with a global warming potential (GWP) of 23–36, therefore reducing levels in the atmosphere can have a significant impact on climate change. There are a range of anthropogenic sources of methane that could be collected and processed to provide sustainable energy (upcycled), e.g., agricultural waste and the waste water system. This paper explores the impact of using upcycled methane in transport in South East England, evaluating local sources of anthropogenic methane and the environmental and economic impact of its use for a heavy-duty truck compared to fossil and battery electric alternatives. Analysis concludes that the use of upcycled methane in transport can provide significant reductions in lifecycle GHG emissions compared to diesel, fossil natural gas or battery electric trucks, and give net negative GHG emissions where avoided environmental methane emissions are considered. Furthermore, upcycling solutions can offer a lower cost route to GHG reduction compared to electrification.

Concerns over the impact of road transport emissions on the climate have led to increased focus on how CO₂ emissions could be reduced from the sector. This is of particular concern in the commercial vehicle sector, where engine downsizing and electrification have limited benefit due to the vehicle duty cycle. In this paper, we present results from an experimental program to investigate the impact of dual fueling a heavy duty engine on hydrogen and diesel. Hydrogen is potentially a zero carbon fuel, if manufactured from renewable energy but could also be manufactured on the vehicle through steam reformation of part of the liquid fuel. This opens a novel pathway for the recovery of waste heat from the exhaust system through the endothermic steam reformation process, improving the overall system efficiency. For these concepts to be viable, it is essential the dual fueled combustion system is both thermally efficient, and does not increase toxic emissions such as NO_x. The test program reported studied the impact of hydrogen injection into the engine intake system with and without Exhaust Gas Recirculation (EGR). The baseline engine was calibrated to achieve Euro VI NO_x emissions with various aftertreatment strategies. The impact of displacing diesel with increased quantities of hydrogen was studied. The results are compared with a conceptual model of the hydrogen - diesel combustion process presented in the paper.