Search

Fabio Mancino,1 Christopher W Jones,1,2 Francesco Benazzo,3,4 Alessandro Singlitico,5 Alessandro Giuliani,5 Ivan De Martino5,6 1Department of Orthopaedics, The Orthopaedic Research Foundation of Western Australia (ORFWA), Fiona Stanley Hospital, Perth, Western Australia, Australia; 2Curtin University, Perth, Western Australia, Australia; 3Sezione di Chirurgia Protesica ad Indirizzo Robotico, Unità di Traumatologia dello Sport, Fondazione Poliambulanza, Brescia, Italy; 4IUSS, Istituto di Studi Superiori, Pavia, Italy; 5Università Cattolica del Sacro Cuore, Roma, Italy; 6Unità di Ortopedia e Traumatologia, Dipartimento di Scienze dell’Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, ItalyCorrespondence: Ivan De Martino, Unità di Ortopedia e Traumatologia, Dipartimento di Scienze dell’Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo A. Gemelli 8, Roma, 00168, Italy, Tel +39 3512412491, Email ivan.demartino@policlinicogemelli.it; drivandemartino@gmail.comAbstract: Robotic-assisted total knee arthroplasty (rTKA) has been developed to improve knee kinematics and functional outcomes, expedite recovery, and improve implants long-term survivorship. Robotic devices are classified into active, semi-active, and passive, based on their degree of freedom. Their capacity to provide increased accuracy in implants positioning with reduced radiographic outliers has been widely proved. However, these early advantages are yet to be associated with long-term survivorship. Moreover, multiple drawbacks are still encountered including a variable learning curve, increased setup and maintenance costs, and potential complications related to the surgical technique. Despite recent technologies applied to TKA have failed to prove substantial improvements, robotic-assisted surgery seems to be here to stay and revolutionize the field of TKA. To support its consistent usage on a daily basis, long-term results are still awaited, and further improvements are necessary to reduce the expenses related to it.Keywords: robotic total knee arthroplasty, knee alignment, accuracy, robot, survivorship, clinical outcomes

Sustainability is a topic that is becoming more and more important in energy production systems. Due to new energy policies, hydrogen is receiving increasing attention as a carbon-free energy carrier embedded in hybrid renewable energy systems (HRES). This paper presents a sustainability analysis of the HRES operation involving electrolytic hydrogen production and conversion to methane through Power-to-Methane (PtM). The analysis is based on day-ahead (DA) scheduling to accomplish the minimum HRES operating cost by comparing two PtM models: A simple rigid model with constant input/output efficiency without hydrogen storage and a linearised electrolyser and methane model with hydrogen storage. The subsequent analysis is conducted by adding heat and gas accumulators in the linearised PtM model to evaluate the added flexibility of these components. Based on the optimal DA programming solution, the three PtM representations are compared based on their respective operating costs and carbon dioxide emissions. The outcomes show that hydrogen into the HRES via a PtM process is not a direct sign of sustainability and that the environmental impact depends on the electricity source provided by the electrolyser. Therefore, this paper highlights that the growth of RES and the integration of PtM should go in synergy and deducting that a more accurate model is required to understand the potential of PtM.

Bornholm plays a central role in the future offshore power expansion in the Baltic Sea and as a node between future interconnections between countries. The necessity to store/convert surplus power puts Bornholm in position to be the first natural energy hub. Bornholm can be not only the centre for electrical equipment such as substations but also a centre for P2X production from offshore wind power. The production of electrofuels through P2X technologies can penetrate the transport sector in Bornholm, the hardest to decarbonise, starting with the highspeed ferries to Ystad and Køge, which use in Rønne Havn as their base. The needs to comply with existing and imminent stricter regulations create the necessity for an immediate transition, before a fleet renewal. Therefore, this study investigates the conversion of the hydrogen, produced using offshore wind electricity, into methanol, whose use as a fuel is mature and does not require substantial changes to the fleet. In this work, three placements for a P2X facility, with a size able to satisfy Rønne Havn demand, are investigated: inside the wind turbines, in Bornholm and Copenhagen. The following results are reached.o The fuel demand for the ferries in Rønne Havn, including all the operations in the port, is estimated to be 237,000 MWh per year (equivalent to 23,300 m3 diesel per year).o The high consumption, 134 MWh per round-trip, of the high-speed ferry currently used creates a barrier to the direct electrification of the ferry, due to high capital cost of the battery and low energy density. o If the electrolyser can access only the electric energy from a 2 GW offshore wind power park near Bornholm, the cost of producing hydrogen in Bornholm is lower than the case in which it is produced in Copenhagen or inside the wind turbine, with a cost of 3-4 €/kg.o The cost of producing H2 in Bornholm and transmitting it via a pipeline to Copenhagen is on the same range of producing the hydrogen in Copenhagen.o The production of hydrogen in Bornholm benefits the utilisation of the HVDC line transmitting the remaining electricity to Copenhagen.o The cost of producing hydrogen is in line with the cost of green H2 in Europe (2.8-3.6 €/kg), but it is higher than its fossil counterparts, grey H2 (0.8-2.9 €/kg) and blue H2 (1.35-2.6 €/kg). The amount of CO2 potentially available from biomass, currently combusted in CHP plants and potentially available for anaerobic digestion, is estimated to be equivalent to 31,423 tonnes per annum, from which 22,853 tonnes per annum of methanol can be produced, equivalent to 126,325 MWh. Therefore, the CO2 is the limiting reactant in the methanol production if the plant is placed on Bornholm.o If the access to the public grid is guaranteed to maintain the production of methanol without shutdowns, a 62.4 MW electrolyser followed by a methanol plant would be required to satisfy the demand for ferries Rønne Havn. However, a 27.6 MW electrolyser would produce the amount of hydrogen that can be converted to methanol, considering the limited CO2 sources.o If the methanol production is placed in Bornholm to satisfy Rønne Havn demand, the green fuel can be produced at 800 €/t, in the case there is nolimitation of CO2 sources, or at 867 €/t in case of limited CO2 sources.o If all the by-products of the electrolysis, oxygen and heat are sold, the cost of production of methanol is reduced to 590 €/t, or to 660 €/t in case of limited CO2 sources.o The cost of the methanol produced in Bornholm is in line with cost ranges for green methanol (260-1,060€/t.). However, the costs result higher than the selling price of fossil methanol ca. 275 €/t.o In conclusion, the placement of the P2X facility results to be more cost-effective in Bornholm, in the case of only-hydrogen production. However, if hydrogen is converted into methanol, the larger access to CO2 sources would favour the placement of the methanol production plant in Copenhagen.o The access to low-cost electricity from renewables and the efficient use of byproducts are vital for the production of electrofuels able to compete with the existing fossil counterparts.

Biomass-derived synthetic natural gas (bio-SNG), produced from biomass through gasification and cleaning and conditioning of syngas, is an energy carrier compatible with the existing gas infrastructure and appliances, is a promising solution for the decarbonisation of transport, heating and electricity generation. However, low energy density and scattered distribution of the resources, technological complexity and high cost of the conversion process, undermine its sustainability. This thesis aimed to deliver a techno-economic and environmental assessment of bio-SNG production, and to build a model that allows identification of the sites and the sizes of the plants for bio-SNG production that minimises the cost and the environmental impact of the bio-SNG produced in the case of the Republic of Ireland. Published life cycle assessments (LCAs) of bio-SNG and biomethane have been reviewed. None of the studies integrated their LCA with both process and geospatial modelling. Therefore a framework including process modelling, to characterise the conversion, and geospatial modelling, to investigate the supply chain configuration, has been proposed in order to assess the environmental and economic sustainability of a spatially-explicit bio-SNG production system and applied in this work. An initial resource assessment identified the distribution and the quantity of all the available resources that can be converted into bio-SNG, showing that 2.5 PJ a-1 of bio-SNG can be provided by forestry residues. A thermodynamic model has been built to simulate the GoBiGas process, a large-scale bio-SNG production plant. This real-case process has been also used as a term of comparison to satisfactorily validate the mass and energy balances and efficiencies resulting from the model. The economies of scale of the process are calculated and finally a geospatial model has been built in order to find the size and the sites of the plant that minimise the unitary cost of bio-SNG produced. The resulting configuration showed that 66.7% of the available forestry residues is processed into a single 71-MW plant, at a cost of 86.3 €/MWh. The environmental impact is then included in the optimisation, as an aggregated single-score of 10 impact categories (climate change, ionising radiation, ozone depletion and resource depletion, eutrophication and acidification potentials, photochemical ozone formation and particulate matter). The single-plant configuration is the one that presents Pareto optimal solutions when compared to multiple plants and considering the minimisation of LCOE and environmental impact as objectives. A 67.6-MW plant minimises environmental impact per Euro spent, presenting benefits for 4 out of 10 of the impact categories considered (climate change, ionising radiation, ozone depletion and resource depletion). The economic and energy potential of bio-SNG from digestate produced from anaerobic digestion (AD) of the organic fraction of municipal solid waste is also assessed as a waste management alternative, resulting in a cost between 89.5 and 109.6 €/MWh, showing results comparable to AD and landspreading of the wet digestate or combustion of the digestate. The methodology presented in this thesis can be applied to any other region where geospatial data are made available and extended to other resources and/or products, providing gas transmission system operators with a tool to integrate renewable gas production technologies into existing infrastructure, minimising the costs and the environmental impact, and evaluating the competitiveness of the renewable gas produced when compared to natural gas.