The EPSRC Centre for Doctoral Training in Renewable Energy Northeast Universities (ReNU) is driven by industry and market needs, which indicate unprecedented growth in renewable and distributed energy to 2050. This growth is underpinned by global demand for electricity which will outstrip growth in demand for other sources by more than two to one (The drivers of global energy demand growth to 2050, 2016, McKinsey). A significant part of this demand will arise from vast numbers of distributed, but interconnected devices (estimated to reach 40 billion by 2024) serving sectors such as healthcare (for ageing populations) and personal transport (for reduced carbon dioxide emission). The distinctive remit of ReNU therefore is to focus on materials innovations for small-to-medium scale energy conversion and storage technologies that are sustainable and highly scalable. ReNU will be delivered by Northumbria, Newcastle and Durham Universities, whose world-leading expertise and excellent links with industry in this area have been recognised by the recent award of the North East Centre for Energy Materials (NECEM, award number: EP/R021503/1). This research-focused programme will be highly complementary to ReNU which is a training-focused programme. A key strength of the ReNU consortium is the breadth of expertise across the energy sector, including: thin film and new materials; direct solar energy conversion; turbines for wind, wave and tidal energy; piezoelectric and thermoelectric devices; water splitting; CO2 valorisation; batteries and fuel cells. Working closely with a balanced portfolio of 36 partners that includes multinational companies, small and medium size enterprises and local Government organisations, the ReNU team has designed a compelling doctoral training programme which aims to engender entrepreneurial skills which will drive UK regional and national productivity in the area of Clean Growth, one of four Grand Challenges identified in the UK Government's recent Industrial Strategy. The same group of partners will also provide significant input to the ReNU in the form of industrial supervision, training for doctoral candidates and supervisors, and access to facilities and equipment. Success in renewable energy and sustainable distributed energy fundamentally requires a whole systems approach as well as understanding of political, social and technical contexts. ReNU's doctoral training is thus naturally suited to a cohort approach in which cross-fertilisation of knowledge and ideas is necessary and embedded. The training programme also aims to address broader challenges facing wider society including unconscious bias training and outreach to address diversity issues in science, technology, engineering and mathematics subjects and industries. Furthermore, external professional accreditation will be sought for ReNU from the Institute of Physics, Royal Society of Chemistry and Institute of Engineering Technology, thus providing a starting point from which doctoral graduates will work towards "Chartered" status. The combination of an industry-driven doctoral training programme to meet identifiable market needs, strong industrial commitment through the provision of training, facilities and supervision, an established platform of research excellence in energy materials between the institutions and unique training opportunities that include internationalisation and professional accreditation, creates a transformative programme to drive forward UK innovation in renewable and sustainable distributed energy.

Metal thin films are used in a wide variety of technologies, such as solar cells and printed circuit boards for electronics. Inkjet printing has emerged as a practical and low-cost route for manufacturing electrical contacts in these applications. However existing manufacturing technologies use inks that often require a final heat treatment to consolidate or 'sinter' the film. If this last step can be eliminated, by depositing fully dense films, then the inkjet manufacturing process could be applied to temperature sensitive substrates like plastics or vulnerable semiconductor materials. The purpose of this project is to develop 'sinter-free' inkjet manufacturing processes, by taking ink precursors developed for other thin film processes, and exploiting them to use the significant benefits of inkjet process technology e.g. the direct writing of interconnects or wires. If successful, the project will represent a step-change in the manufacturing methods for this type of film.

Optical fibres lie at the heart of our increasingly technological society, for example: supporting the internet and mobile communications that we all now take for granted, saving lives through medical diagnosis and interventions using fibre-optic endoscopes, and enabling the mass production of a huge array of commercial products through fibre laser based materials processing. However, current fibre optics technology has its limitations due largely to the fact that the light is confined to a solid glass core. This places fundamental restrictions on the power and wavelength range over which signals can be transmitted, the speed at which signals propagate, and in terms of sensitivity to the external environment. These limits are now starting to impose restrictions in many application areas. For example, in telecommunications, nonlinear interactions between wavelength channels limit the maximum overall data transmission capacity of current single mode fibres to ~100-200 Tbit/s (for amplified terrestrial systems). Moreover, nonlinear, thermal and material damage thresholds combine to limit the maximum peak and average powers that can be delivered in a tightly focusable beam. This restricts the range of potential uses, particularly in the important ultrashort pulse regime increasingly used for a wide variety of materials processing applications These limitations can in principle be overcome by exploiting new light guidance mechanisms in fibres with a hollow core surrounded by a fine glass microstructure. Such fibres are generally referred to as Hollow Core Fibres (HCFs). Within this Programme we will seek to reinvent fibre optics technology and will replace the glass core with air or vacuum to produce Optical Fibres 2.0, offering vastly superior but largely unexplored potential. Our ultimate vision is that of a Connected World, where devices, machines, data centres and cities can be linked through these hollow light pipes for faster, cheaper, more resilient and secure communications. A Greener and Healthier World, where intense laser light can be channelled to produce goods and run combustion engines more efficiently and to image cancer tissues inside our bodies in real time. And an Explorative World, where hollow lightguides will enable scientific breakthroughs in attosecond science, particle physics, metrology and interplanetary exploration. Our overall ambition is therefore to revisit the way we think about light guidance and to develop a disruptive technology that challenges conventional thinking. The programme will provide the UK with a world-leading position both in HCF technology itself and in the many new applications and services that it will support.

Precision laser processing has much potential for advanced manufacturing. Features can be machined at a fraction of a micrometre in size in a wide range of materials. The use of ultrashort laser pulses (with duration less than a picosecond) is important since all of the laser pulse energy is delivered to the focus in a timescale shorter than that for thermal diffusion. Therefore, all the material machining is done before any energy can escape as heat, which underpins the high resolution of the technique. Ultrashort laser pulses provide other unique opportunities, since they can be used for three-dimensional fabrication inside transparent materials, with a range of applications for smart technology. Such precision laser processing is already applied on an industrial scale, with examples such as accurate cutting of glass for smartphones or multi-dimensional data storage. With a constant drive for miniaturisation and enhanced functionality, the sector is destined to blossom over the next decade. The ability to fabricate features at the sub-micrometre scale presents many opportunities for advanced technology. However, accurate positioning of such small features in three dimensions inside centimetre scale workpieces creates a serious challenge. Machine vision uses imaging solutions integrated inside the manufacturing system to provide feedback for the laser process to ensure that the device is machined as designed. However, existing hardware and software systems cannot meet the challenging demands of such high precision laser processing. In this project, we develop new hardware and software solutions that will enable rapid three-dimensional imaging at high resolution. We also introduce new systems that can provide a macroscopic view of the entire device being processed. Additionally we establish innovative forms of optical feedback that can be applied to closely monitor the laser manufacturing process. All of this information is merged together inside a cohesive software framework, that can provide quick data transfer of important information to the laser manufacturing system. This enables quicker, more accurate laser processing of smaller features in demanding applications, to enable industrial scale manufacturing of advanced technology.

Techniques such as abrasive water jet machining (AWJ), pulsed laser ablation (PLA) and ion beam machining (IBM) are all methods of energy beam processing, by which energy is transferred to a surface and material is removed; this group of technologies can be employed to generate freeforms surfaces by controlled-depth machining. Although the way in which the energy is transferred in each of these methods is very different (AWJ: a high speed mixture of air, grit and water mechanically erodes the surface; PLA: laser pulses vaporize the surface; IBM: high speed charged particles erode the surface), they can be dealt under a unified mathematical framework whereby the rate of erosion of the surface is described by a partial differential equation. This equation relates the footprint of an energy beam (its instantaneous rate of removal, which may be a function of the geometry of the eroding surface, its distance from the source of the beam as well as position within the beam and beam orientation) to the evolution of the surface. The Investigators in this proposal have had significant success in using this mathematical framework to determine the final, machined surface for a given beam footprint and dynamic beam path; this is the forward problem. However, the problem that is of industrial interest is the inverse problem; given a required final surface, how should the beam be moved in order to accurately machine it? Currently, in both academic research and industry, this problem is solved by trial and error (craftmanship). The aim of this project is to develop methods for solving the inverse problem algorithmically, so that end users of this group of technologies (i.e. energy beam controlled-depth machining) can input their required surface into a software package and automatically generate a beam path. We will do this by tackling a series of increasingly realistic mathematical problems which can be related to real energy beam processes, backed up by an experimental programme against which our models can be verified.