United Kingdom

The three years European MATHRYCE project dedicated to material testing and design recommendations for components exposed to hydrogen enhanced fatigue started in October 2012. Its main goal is to provide an “easy” to implement methodology based on lab-scale experimental tests under hydrogen gas to assess the service life of a real scale component taking into account fatigue loading under hydrogen gas. Dedicated experimental tests will be developed for this purpose. In the present paper the proposed approach is presented and compared to the methodologies currently developed elsewhere in the world.

In the present work the computational fluid dynamics (CFD) code ADREA-HF has been applied to simulate the very recent liquefied hydrogen spill experiments performed by the Health Safety Laboratory (HSL). The experiment consists of four LH2 release trials over concrete at a fixed rate of 60 lt/min but with different release direction height and duration. In the modeling the hydrogen source was treated as a two phase jet enabling simultaneous modeling of pool formation spreading as well as hydrogen vapor dispersion. Turbulence was modeled with the standard k- model modified for buoyancy effects. The effect of solidification of the atmospheric humidity was taken into account. The predicted concentration at the experimental sensors? locations was compared with the observed one. The results from the comparison of the predicted concentration with and without solidification of the atmospheric humidity indicate that the released heat from the solidification affects significantly the buoyant behavior of the hydrogen vapor. Therefore the simulation with solidification of the atmospheric humidity is in better agreement with the experiment.

Fuel cell based micro-combined heat and power (CHP) units used for domestic applications can provide significant cost and environmental benefits for end users and contribute to the UK’s 2050 emissions target by reducing primary energy consumption in dwellings. Lately there has been increased interest in the development of systematic methods for the design of such systems and their smoother integration with domestic building services. Several models in the literature whether they use a simulation or an optimisation approach ignore the dwelling side of the system and optimise the efficiency or delivered power of the unit. However the design of the building services is linked to the choice of heating plant and its characteristics. Adding the dwelling’s energy demand and temperature constraints in a model can produce more general results that can optimise the whole system not only the micro-CHP unit. The fuel cell has various heat streams that can be harvested to satisfy heat demand in a dwelling and the design can vary depending on the proportion of heat needed from each heat stream to serve the energy demand. A mixed integer non-linear programming model (MINLP) that can handle multiple heat sources and demands is presented in this paper. The methodology utilises a process systems engineering approach. The model can provide a design that integrates the temperature and water flow constraints of a dwelling’s heating system with the heat streams within the fuel cell processes while optimising total CO₂ emissions. The model is demonstrated through different case studies that attempt to capture the variability of the housing stock. The predicted CO₂ emissions reduction compared to a conventionally designed building vary from 27% to 30% and the optimum capacity of the fuel cell ranges between 1.9 kW and 3.6 kW. This research represents a significant step towards an integrated fuel cell micro-CHP and dwelling design.

Ni-based catalysts are attractive alternatives to noble metal electrocatalysts for the hydrogen evolution reaction (HER). Herein we present a dispersion-corrected density functional theory (DFT-D3) insight into HER activity on the (111) (110) (001) and (100) surfaces of metallic nickel nitride (Ni₃N). A combination of water and hydrogen adsorption was used to model the electrode interactions within the water splitting cell. Surface energies were used to characterise the stabilities of the Ni3N surfaces along with adsorption energies to determine preferable sites for adsorbate interactions. The surface stability order was found to be (111) < (100) < (001) < (110) with calculated surface energies of 2.10 2.27 2.37 and 2.38 Jm⁻² respectively. Water adsorption was found to be exothermic at all surfaces and most favourable on the (111) surface with E_ads = −0.79 eV followed closely by the (100) (110) and (001) surfaces at −0.66 −0.65 and −0.56 eV respectively. The water splitting reaction was investigated at each surface to determine the rate determining Volmer step and the activation energies (Ea) for alkaline HER which has thus far not been studied in detail for Ni₃N. The E_a values for water splitting on the Ni₃N surfaces were predicted in the order (001) < (111) < (110) < (100) which were 0.17 0.73 1.11 and 1.60 eV respectively overall showing the (001) surface to be most active for the Volmer step of water dissociation. Active hydrogen adsorption sites are also presented for acidic HER evaluated through the ΔG_H descriptor. The (110) surface was shown to have an extremely active Ni–N bridging site with ΔG_H = −0.05 eV.

Iron oxide has been widely used as an oxygen carrier material (OCM) for hydrogen production by chemical looping due to its favourable thermodynamic properties. In spite of this iron oxide loses much of its activity after redox cycling mainly due to sintering and agglomeration. Perovskites such as La_0.7Sr_0.3FeO_3-d (LSF731) have been suggested as potential candidate OCMs for hydrogen production due to their excellent oxygen transport properties and stability under cycling. However hydrogen production per cycle for a similar carrier weight is lower than with iron oxide. This work proposes the use of composite OCMs made of iron oxide clusters embedded in an LSF731 matrix. The perovskite matrix facilitates oxygen transport to the iron oxide clusters while preventing agglomeration. Two preparation methods mechanical mixing and a modified Pechini method were used to obtain composite materials with different iron oxide weight fractions 11 and 30 wt.%. The reactivity of these OCMs was studied in a thermogravimetric analyser. Hydrogen production and carrier stability were investigated in a microreactor over 25 redox cycles while periodically feeding carbon monoxide and water in order to produce carbon dioxide and hydrogen in separate streams. Hydrogen production was stable over 25 cycles for LSF731 and the composite OCM with 30 wt.% iron oxide produced by the modified Pechini method but iron oxide particles alone underwent a decrease in the hydrogen production with cycling. The hydrogen production during the 25th cycle was eight times higher for the composite material than for iron oxide alone and four times higher than for LSF731. The hydrogen production was therefore also higher than that expected from a simple combination of the iron oxide and LSF731 alone indicating a synergetic effect whereby the LSF731 may have a higher effective oxygen capacity when in the form of the composite material.

The paper presents an experimental investigation of hydrogen-diesel fuel co-combustion carried out on a naturally aspirated direct injection diesel engine. The engine was supplied with a range of hydrogen-diesel fuel mixture proportions to study the effect of hydrogen addition (aspirated with the intake air) on combustion and exhaust emissions. The tests were performed at fixed diesel injection periods with hydrogen added to vary the engine load between 0 and 6 bar IMEP. In addition a novel inecylinder gas sampling technique was employed to measure species concentrations in the engine cylinder at two inecylinder locations and at various instants during the combustion process. The results showed a decrease in the particulates CO and THC emissions and a slight increase in CO2 emissions with the addition of hydrogen with fixed diesel fuel injection periods. NOx emissions increased steeply with hydrogen addition but only when the combined diesel and hydrogen co-combustion temperatures exceeded the threshold temperature for NOx formation. The inecylinder gas sampling results showed higher NOx levels between adjacent spray cones in comparison to sampling within an individual spray cone.

The use of so-called “green” hydrogen for decarbonisation of the energy and propulsion sectors has attracted considerable attention over the last couple of decades. Although advancements are achieved hydrogen still presents some constraints when used directly in power systems such as gas turbines. Therefore another vector such as ammonia can serve as a chemical to transport and distribute green hydrogen whilst its use in gas turbines can limit combustion reactivity compared to hydrogen for better operability. However pure ammonia on its own shows slow complex reaction kinetics which requires its doping by more reactive molecules thus ensuring greater flame stability. It is expected that in forthcoming years ammonia will replace natural gas (with ~ 90% methane in volume) in power and heat production units thus making the co-firing of ammonia/methane a clear path towards replacement of CH4 as fossil fuel. Hydrogen can be obtained from the precracking of ammonia thus denoting a clear path towards decarbonisation by the use of ammonia/hydrogen blends. Therefore ammonia/methane/hydrogen might be co-fired at some stage in current combustion units hence requiring a more intrinsic analysis of the stability emissions and flame features that these ternary blends produce. In return this will ensure that transition from natural gas to renewable energy generated e-fuels such as so-called “green” hydrogen and ammonia is accomplished with minor detrimentals towards equipment and processes. For this reason this work presents the analysis of combustion properties of ammonia/methane/hydrogen blends at different concentrations. A generic tangential swirl burner was employed at constant power and various equivalence ratios. Emissions OH*/NH*/NH2*/CH* chemiluminescence operability maps and spectral signatures were obtained and are discussed. The extinction behaviour has also been investigated for strained laminar premixed flames. Overall the change from fossils to e-fuels is led by the shift in reactivity of radicals such as OH CH CN and NH2 with an increase of emissions under low and high ammonia content. Simultaneously hydrogen addition improves operability when injected up to 30% (vol) an amount at which the hydrogen starts governing the reactivity of the blends. Extinction strain rates confirm phenomena found in the experiments with high ammonia blends showing large discrepancies between values at different hydrogen contents. Finally a 20/55/25% (vol) methane/ammonia/hydrogen blend seems to be the most promising at high equivalence ratios (1.2) with no apparent flashback low emissions and moderate formation of NH2/OH radicals for good operability.

Heating and hot water for UK buildings make up 40% of our energy consumption and 20% of our greenhouse gas emissions. It will be necessary to largely eliminate these emissions by around 2050 to meet the targets in the Climate Change Act and to maintain the UK contribution to international action under the Paris Agreement.<br/>Progress to date has stalled. The Government needs a credible new strategy and a much stronger policy framework for buildings decarbonisation over the next three decades. Many of the changes that will reduce emissions will also contribute toward modern affordable comfortable homes and workplaces and can be delivered alongside a major expansion in the number of homes. This report considers that challenge and sets out possible steps to meet it.

The following report accompanies the Committee on Climate Change’s 2017 report on energy prices and bills. It was written by Ricardo Energy and Environment.

The report provides an analysis of the opportunities to UK businesses to supply global markets with low carbon materials and goods and services. The report considers: the position of the current UK low carbon economy the size of the market opportunity for UK businesses in 2030 and 2050 the barriers to UK business capturing a larger share of the global market the opportunity to increase the UK’s share of future global markets

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The Paris Agreement marks a significant positive step in global action to tackle climate change. This report considers the domestic actions the UK Government should take as part of a fair contribution to the aims of the Agreement.<br/>The report concludes that the Paris Agreement is a significant step forward in global efforts to tackle climate change. It is more ambitious in its aims to limit climate change than the basis of the UK’s existing climate targets. However it is not yet appropriate to set new UK targets. Existing targets are already stretching and the priority is to take action to meet them.