Fuel Standards Summary

This document aims to provide a comprehensive overview of the standards relating to fuel use in the UK. It can be used to gain an initial insight into which regulations must be considered when developing bio-based alternatives and the potential composition limits to meet current fuel quality specifications

Forecasting Impact: a case study of bioenergy systems

One of the main drivers for the use of bioenergy is the reduction in GHG emissions. Bioenergy is a versatile energy source that is not only storable, but is also able to be used in many ways, for example as fuel for transport, electricity and/or heat. There are advantages (and disadvantages) of using bioenergy for each vector, and impacts vary due to region, technology, and pathways. However, there is not enough bioenergy to meet all of our energy demand and therefore it must be used alongside other energy sources. Determining how to optimise its use is critical for policy makers and industry.In order to understand the optimal use for bioenergy, assessments have been undertaken on several pathways to determine their life cycle impacts. Nevertheless, bioenergy is a fast evolving area with new pathways and feedstock utilisation being developed and proposed at pace. At the other end of the scale, governments and policy makers are trying to determine the best use of existing resources and the impact of (semi) disruptive systems. Exploring the impact of varying emerging and existent bioenergy vectors, not just in terms of production, but in terms of their ability to disrupt current systems, is complex. This research explores the use of bioenergy in heating systems. Several anticipatory pathways are explored, for example the production and use of biogas in existing gas networks and the use of bioenergy on a more local scale for heating through CHP. Without CCS, bioenergy still emits GHGs during its use. However, as CO2 can be reabsorbed by replacement feedstocks over a relevant timescale, its impact is arguably less.This is questioned by some; but what is clear is that timescale is critical. The recent IPCC report suggests we have 12 years to limit catastrophic climate change. So any mechanisms we have for optimising systems must consider the short-term impacts as well as the traditionally longer timescale reported within conventional LCA.This work highlights the significance of the differing GHGs on a temporal scale as the time GHGs remain in the atmosphere varies substantially. For example, methane (CH4) has a higher GWP, but a shorter lifetime than CO2. This means that emissions of CH4 will have higher impacts for a shorter period of time, meaning it is a critical emission to manage in order to minimise our immediate impact on climate change.The research demonstrates that GWP impacts should be reported against a range of timescales; or at a minimum, that different GHG emissions should be distinguished and supports the development of a mechanism to identify both longer and critically, shorter, term pathways to GHG reduction

Simulation of soil carbon efflux from an arable soil using the ECOSSE model: Need for an improved model evaluation framework?

Globally, it is estimated that ~ 1500 Pg C of organic carbon is stored in the top meter of terrestrial soils. This represents the largest terrestrial pool of carbon. Appropriate management of soils, to maintain or increase the soil carbon pool, represents a significant climate change mitigation opportunity. To achieve this, appropriate tools and models are required in order to more accurately estimate soil carbon fluxes with a view to informing and developing more effective land use management strategies. Central to this is the evaluation of models currently in use to estimate soil carbon emissions. In the present study, we evaluate the ECOSSE (Estimating Carbon in Organic Soils – Sequestration and Emissions) model which has its origins in both SUNDIAL and RothC and has been widely used globally to model soil CO2 fluxes across different locations and land-use types on both organic and mineral soils. In contrast to previous studies, the model was found to poorly represent observed soil respiration at the study site, an arable cropland on mineral soil located in south-east Ireland. To isolate potential sources of error, the model was decomposed into its component rate equations or modifiers. This investigation highlighted a deficiency in the model simulated soil water, resulting in significant inhibition of the model simulated CO2 flux relative to the observed data. When measured values of soil water at the site were employed, the model simulated soil respiration improved significantly (r2 of 0.775 vs 0.154). This highlighted model deficiency remains to be evaluated at other sites; however, the research highlights the need for a more comprehensive evaluation of soil carbon models prior to their use in informing policy, particularly models which are employed at larger scales and for climate change projections

Simulation of soil carbon efflux from an arable soil using the ECOSSE model: Need for an improved model evaluation framework?

Globally, it is estimated that ~ 1500 Pg C of organic carbon is stored in the top meter of terrestrial soils. This represents the largest terrestrial pool of carbon. Appropriate management of soils, to maintain or increase the soil carbon pool, represents a significant climate change mitigation opportunity. To achieve this, appropriate tools and models are required in order to more accurately estimate soil carbon fluxes with a view to informing and developing more effective land use management strategies. Central to this is the evaluation of models currently in use to estimate soil carbon emissions. In the present study, we evaluate the ECOSSE (Estimating Carbon in Organic Soils – Sequestration and Emissions) model which has its origins in both SUNDIAL and RothC and has been widely used globally to model soil CO2 fluxes across different locations and land-use types on both organic and mineral soils. In contrast to previous studies, the model was found to poorly represent observed soil respiration at the study site, an arable cropland on mineral soil located in south-east Ireland. To isolate potential sources of error, the model was decomposed into its component rate equations or modifiers. This investigation highlighted a deficiency in the model simulated soil water, resulting in significant inhibition of the model simulated CO2 flux relative to the observed data. When measured values of soil water at the site were employed, the model simulated soil respiration improved significantly (r2 of 0.775 vs 0.154). This highlighted model deficiency remains to be evaluated at other sites; however, the research highlights the need for a more comprehensive evaluation of soil carbon models prior to their use in informing policy, particularly models which are employed at larger scales and for climate change projections

Submillimeter Observations of the Ultraluminous BAL Quasar APM 08279+5255

With an inferred bolometric luminosity of 5\times10^{15}{\rm \lsun}, the recently identified z=3.87, broad absorption line quasar APM 08279+5255 is apparently the most luminous object currently known. As half of its prodigious emission occurs in the infrared, APM 08279+5255 also represents the most extreme example of an Ultraluminous Infrared Galaxy. Here, we present new submillimeter observations of this phenomenal object; while indicating that a vast quantity of dust is present, these data prove to be incompatible with current models of emission mechanisms and reprocessing in ultraluminous systems. The influence of gravitational lensing upon these models is considered and we find that while the emission from the central continuum emitting region may be significantly enhanced, lensing induced magnification cannot easily reconcile the models with observations. We conclude that further modeling, including the effects of any differential magnification is required to explain the observed emission from APM 08279+5255.Comment: 12 Pages with Two figures. Accepted for publication in the Astrophysical Journal Letter

Exploring temporal aspects of climate-change effects due to bioenergy

The greenhouse gas emissions associated with bioenergy are often temporally dispersed and can be a mixture of long-term forcers (such as carbon dioxide) and short-term forcers (such as methane). These factors affect the timing and magnitude of climate-change impacts associated with bioenergy in ways that cannot be clearly communicated with a single metric. This is critical as key comparisons that determine incentives and policy for bioenergy are based upon climate-change impacts expressed as carbon dioxide equivalent calculated with GWP100. This paper explores these issues further and presents a spreadsheet tool to facilitate quick assessment of these temporal effects. The potential effect of (i) a mix of GHGs and (ii) emissions that change with time are illustrated through two case studies. In case study 1, variations in the mix of greenhouse gases mean that apparently similar impacts after 100-years, mask radically different impacts before then. In case study 2, variations in the timing of emissions cause their climate-change impacts (integrated radiative-forcing and temperature change) to differ from the impacts that an emissions-balance would suggest. The effect of taking alternative approaches to considering “CO2-equivalence” are also assessed. In both cases, a single metric for climate-change effects was found to be wanting. A simple tool has been produced to help practitioners evaluate whether this is the case for any given system. If complex dynamics are apparent, it is recommended that additional metrics, more detailed inventory, or full time-series impact results are used in order to accurately communicate these climate-change effects.</p

Hubble Space Telescope Wide Field Planetary Camera 2 observations of hyperluminous infrared galaxies

We present Hubble Space Telescope Wide Field Planetary Camera 2 I-band imaging for a sample of nine hyperluminous infrared galaxies (HLIRGs) spanning a redshift range 0.45 &lt; z &lt; 1.34. Three of the sample have morphologies showing evidence for interactions and six are quasi-stellar objects (QSOs). Host galaxies in the QSOs are detected reliably out to z ∼ 0.8. The detected QSO host galaxies have an elliptical morphology with scalelengths spanning 6.5 &lt; re (kpc) &lt; 88 and absolute k-corrected magnitudes spanning −24.5 &lt; MI &lt; −25.2. There is no clear correlation between the infrared (IR) power source and the optical morphology. None of the sources in the sample, including F15307+3252, shows any evidence for gravitational lensing. We infer that the IR luminosities are thus real. Based on these results, and previous studies of HLIRGs, we conclude that this class of object is broadly consistent with being a simple extrapolation of the ULIRG population to higher luminosities; ULIRGs being mainly violently interacting systems powered by starbursts and/or active galactic nuclei. Only a small number of sources, the infrared luminosities of which exceed 1013 L⊙, are intrinsically less luminous objects that have been boosted by gravitational lensing