h i g h l i g h t sWe describe a detailed design methodology for ORC radial turbo expanders. Toluene is selected as the working fluid for diesel engine waste energy recovery. A first turbine of 15.5 kW is designed but yields too small inlet blade heights. A second turbine for minimum power generates 34.1 kW with 51.5% efficiency. A third turbine for maximum efficiency produces 45.6 kW at 56.1% efficiency. a b s t r a c tFuture vehicles for clean transport will require new powertrain technologies to further reduce CO 2 emissions. Mobile organic Rankine cycle systems target the recovery of waste heat in internal combustion engines, with the exhaust system identified as a prime source. This article presents a design methodology and working fluid selection for radial turbo expanders in a heavy-duty off-road diesel engine application. Siloxanes and Toluene are explored as the candidate working fluids, with the latter identified as the preferred option, before describing three radial turbine designs in detail. A small 15.5 kW turbine design leads to impractical blade geometry, but a medium 34.1 kW turbine, designed for minimum power, is predicted to achieve an isentropic efficiency of 51.5% at a rotational speed of 91.7 k min À1 . A similar 45.6 kW turbine designed for maximum efficiency yields 56.1% at 71.5 k min À1 . This emphasizes the main design trade-off -efficiency decreases and rotational speed increases as the power requirement fallsbut shows reasonable radial turbine efficiencies and thus practical turbo expanders for mobile organic Rankine cycle applications are realizable, even considering the compromised flow geometry and high speeds imposed at such small scales.

Material efficiency is indispensable to reaching agreed targets for industry's energy and carbon emissions. Yet, in the EU, the energy-and emissions-saving potentials of this strategy continue to be framed as secondary outcomes of resource-related policies. Understanding why material efficiency has been overlooked as an energy/climate solution is a prerequisite for proposing ways of changing its framing, but existing studies have failed to do so. This paper fills this gap by triangulating interviews, policy documents and three policy theories: namely, historical and rational choice institutionalism, and multiple streams framework. Factors discouraging material efficiency as an energy and climate strategy include: difficulties in reframing the prevailing rationale to pursue it; the inadequacy of monitored indicators; the lack of high-level political buy-in from DG Energy and Clima; the ETS policy lock-in; uncoordinated policy management across Directorates; the lack of a designated industry lobby. Policy solutions are proposed. Before 2030, these are limited to minor amendments, e.g. guidance on embodied energy calculations or industry standards. Post-2030, more radical interventions are possible, such as introducing new fiscal drivers, redesigning the ETS emissions cap or benchmarks for allowances. This evidence suggests that the transition to a low-carbon industry will require Member State-and industry-level action.

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The production of steel, a key enabler of modern societal development, is responsible for over a quarter of industry's carbon dioxide (CO 2) emissions (IEA, 2016). The International Energy Agency's (IEA) 2ºC scenario for 2050 suggests that more than a third of the emissions reduction in industry (excluding power generation) will come from the steel sector, making steel the single largest contributor to industrial emissions reduction. Energy efficiency (EE) and material efficiency (ME) strategies, the combination of which is defined as resource efficiency (RE) in this article, are expected to deliver significant emissions reductions in the short term, especially while decarbonisation technologies such as smeltreduction and carbon capture and storage are still under development. In fact, in their Material Efficiency Scenario, the (IEA, 2015a) shows "material efficiency could deliver larger energy savings in energy-intensive industries than energy efficiency" especially in the steel industry. Customarily, to determine the improvement potential available from EE, the scale of the energy flows in a system is traced, and both a current and a target efficiency are defined. Yet performing a similar task for industry, where the main product outputs are materials, cannot be appropriately accomplished by solely evaluating the flows and efficiency of energy. In real industrial processes, including steelmaking, material and energy inputs interact and undergo chemical reactions to produce a range of energy and material products. Neglecting materials when analysing industrial RE only provides a myopic picture. To quantify the potential resource and emissions savings in the steel industry, a holistic understanding of both types of resources and appropriate metrics that capture their interactions is needed.