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The aggravating global problems of energy crisis, rising atmospheric greenhouse gas concentrations and accumulation of persistent waste have attracted the attention of scientists, policy-makers and global organisations to come up with effective and expeditious solutions to address these challenges. In this context, the development of sustainable technologies driven by renewable energy sources for the production of clean fuels and commodity chemicals from diverse waste feedstocks is an appealing approach towards creating a circular economy. Over the years, semiconductor photocatalysts based on TiO₂, CdS, carbon-nitrides (CNx) and carbon dots (CDs) have been widely used for the photocatalytic reforming (PC reforming) of pre-treated waste substrates to organic products, accompanied with clean hydrogen (H₂) generation. However, these conventional solar-driven processes suffer from major drawbacks such as low production rates, poor product selectivity, CO₂ release, challenging process and catalyst optimisation, and harsh waste pre-treatment conditions, which limit their commercial applicability. These challenges are tackled in this thesis with the introduction of new and efficient photoelectrochemical (PEC) and chemoenzymatic processes for reforming a diverse range of waste feedstocks to sustainable fuels. Solar-driven PEC reforming based on halide perovskite light-absorber is first developed as an attractive alternative to PC reforming. The PEC systems consist of a perovskite|Pt photocathode for clean H₂ production and a Cu-Pd alloy anode for reforming diverse waste streams, including pre-treated cellulosic biomass, polyethylene terephthalate (PET) plastics, and industrial by-product glycerol into industrially-relevant, value-added chemicals (gluconic acid, glycolic acid and glyceric acid) without any externally applied bias or voltage. Additionally, the single light-absorber PEC systems can also convert the airborne waste stream and greenhouse gas CO₂ to diverse products with the simultaneous reforming of PET plastics with no applied voltage. The perovskite-based photocathode enables the integration of different CO₂ reduction catalysts such as a molecular cobalt porphyrin, a Cu-In alloy and formate dehydrogenase enzyme, which produce CO, syngas and formate, respectively. The versatile PEC systems, which can be assembled in either a ‘two-compartment’ or standalone ‘artificial leaf’ configurations achieve 60‒90% oxidation product selectivity (with no over-oxidation) and >100 µmol cm‾² h‾¹ product formation rates, corresponding to 10²‒10⁴ times higher activity than conventional PC reforming systems. In addition to developing PEC platforms, this thesis also explores avenues for circumventing the harsh alkaline pre-treatment strategies (pH >13, 60‒80 ºC) adopted for photoreforming waste substrates. For this purpose, a chemoenzymatic pathway is introduced whereby PET and polycaprolactone plastics were deconstructed using functional enzymes under benign conditions (pH 6‒8, 37‒65 ºC), followed by PC reforming using Pt loaded TiO₂ (TiO₂|Pt) or Ni₂P loaded carbon-nitride (CNx|Ni₂P) photocatalysts. The chemoenzymatic reforming process demonstrates versatility in upcycling polyester films and nanoplastics for H₂ production at high yields reaching ∼10³‒10⁴ µmol gsub‾¹ and activities at >500 µmol gcat‾¹ h‾¹. The utilisation of enzyme pre-treated plastics also allowed the coupling of plastic reforming with photocatalytic CO₂-to-syngas conversion using a phosphonated cobalt bis(terpyridine) co-catalyst immobilised on TiO₂ (TiO₂|CotpyP). Finally, moving beyond solar-driven systems, a bio-electrocatalytic flow process is demonstrated for the conversion of microbe pre-treated food waste to ethylene (an important feedstock in the chemical industry) on graphitic carbon electrodes via succinic acid as the central intermediate. In conclusion, with its focus on improving efficiencies, achieving selective product formation, building versatile platforms, diversifying substrate and product scope, and reducing carbon footprint and economic strain, this thesis aims to bring sustainable waste-to-fuel technologies a step closer to commercial implementation.

National net zero emission targets could, if fully implemented, reduce best estimates of projected global average temperature increase to 2.0–2.4 °C by 2100, bringing the Paris Agreement temperature goal within reach. A total of 131 countries are discussing, have announced or have adopted net zero targets, covering 72% of global emissions. These targets could substantially lower projected warming as compared to currently implemented policies (2.9–3.2 °C) or pledges submitted to the Paris Agreement (2.4–2.9 °C). Current pledges for emissions cuts are insufficient to meet the Paris Agreement temperature goal. The wave of net zero targets being discussed and adopted could make the Paris goal possible if further countries follow suit.

Abstract While it is generally accepted that our fossil fuel-dominated energy systems must undergo a sustainable transition, researchers have often neglected the potential impacts of this on water and land systems. However, if unintended environmental impacts from this process are to be avoided, understanding its implications for land use and water demand is of crucial importance. Moreover, developed countries may induce environmental stress beyond their own borders, for instance through extensive imports of bioenergy. In this paper, Germany serves as an example of a developed country with ambitious energy transformation targets. Results show that in particular, the politically-driven aspiration for more organic farming in Germany results in a higher import quota of biomass, especially biofuels. These imports translate into land demand, which will exceed the area available in Germany for bioenergy by a factor of 3–6.5 by 2050. As this will likely bring about land stress in the respective exporting countries, this effect of the German energy transformation ought to be limited as much as possible. In contrast, domestic water demand for the German energy system is expected to decrease by over 80% through 2050 due to declining numbers of fossil-fuelled power plants. However, possible future irrigation needs for bioenergy may reduce or even counterbalance this decreasing effect. In addition, energy policy targets specific to the transport sector show a high sensitivity to biomass imports. In particular, the sector-specific target for greenhouse gas reductions will seemingly promote biomass imports, leading to the above-described challenges in the pursuit of sustainability.

AbstractThe Homeless Heritage project took place across two English cities (Bristol and York) between 2010 and 2014. The project sought to use a range of participatory heritage practices to engage contemporary homeless people in documenting their perspectives on each city. Drawing on data gathered over three and a half years this paper reflects on how collaborative cultural heritage practices can be useful in recording diverse stakeholder perspectives which can become catalysts for social change. It is further argued that two interactive exhibitions that resulted from the Homeless Heritage project contributed to the democratisation of knowledge, aiding negotiation of the complicated politics of contemporary homelessness in valuable ways.

This paper assesses the capacity of Whitehouse, Jamaica to adapt to climate change. A community-based vulnerability assessment was conducted that employed semi-structured interviews with community members within or related to the tourism, fisheries and agricultural sectors. The results were analysed using the Local Adaptive Capacity (LAC) framework, which characterises adaptive capacity based on five elements: asset base; institutions and entitlements; knowledge and information; innovation; and flexible forward-looking decision-making and governance. This paper contributes to the literature in three ways. First, it argues that many elements of the LAC framework correspond with an evolutionary perspective on adaptive capacity. Second, it offers an in-depth case study of the capacity of Whitehouse to adapt to climate change. Third, it offers a critical assessment of whether the LAC framework fully captures the important elements of adaptive capacity.

Green energy technologies (GETs) are environmentally friendly in nature, making a promising contribution to attaining net-zero carbon goals. Although the Pakistani government has begun using GETs to minimize the adverse effects of carbon emissions, consumers' adoption rate is quite low. There are few studies examining consumers' desire to adopt GETs in the country. This study attempts to fill this research gap and also contributes by adding three novel factors to the theory of planned behavior (i.e., green energy technology awareness, openness to experience, and green energy technology discomfort) to comprehensively analyze the impact of various factors influencing consumers' desire to adopt GETs. For this purpose, the study establishes a systematic research framework. Data were collected from (n = 330) households in the five major cities (Peshawar, Abbottabad, Mardan, Mingora, and Swabi) of Khyber Pakhtunkhwa Province via an inclusive questionnaire survey. The formulated hypotheses are evaluated and scrutinized using structural equation modeling. The results reveal that environmental concern (β = 0.245), green energy technology awareness (β = 0.362), openness to experience (β = 0.256), and green energy technology benefits (β = 0.225) positively affect consumers' desire to adopt GETs. On the other hand, green energy technology costs (β = 0.325) and green energy technology discomfort (β = 0.395) have a negative effect on consumers' adoption of GETs. The research findings emphasize the importance of increasing recognition of GETs, reforming policy frameworks, and providing budget-friendly and user-friendly technologies. Research limitations and future research perspectives are also addressed.

Abstract Urban transformation is vital to global sustainable development as humans increasingly come to dwell in cities. Within cities, the mobility sector promises the highest potential of carbon emission reduction. The disruptive business innovation brought about by the advent of app-based smart-sharing systems is emancipating collaborative consumption of mobility at larger and deeper scales, ranging from car-pooling, expanded electric vehicle (EV) use to bike-sharing. Synchronizing the existing yet under-realized low-carbon transport modes in cities, such as public transport, with emerging and diversifying app-based sharing mobility business models, offers huge potential to transform urban mobility toward sustainability. Yet, the rapid business expansion and innovation of the sharing mobility companies have profoundly challenged existing socio-economic relationships, knowledge systems and physical infrastructures in cities. This study explores the synergy between the social-ecological innovation in the sharing economy and the sustainable development of urban systems, using empirical data from three business cases in the emerging sharing mobility sector – in modes of ride-sharing, EV-sharing and bike-sharing - of Shanghai, China. It indicates that there is a strong co-evolution mechanism between the transformation towards more sustainable city at the macro-level and the business ecosystem innovation towards greener and smarter transport at the meso-level. We argue that the two level transformations, triggered by the disruptive innovation of the sharing economy and led by urban transformation towards sustainability, mutually influence each other and re-enforce sustainable values and practices in the fast changing urban context and business innovations in Shanghai.

The climate crisis is the biggest threat to the health, development, and wellbeing of the current and future generations. While there is extensive evidence on the direct impacts of climate change on human livelihood, there is little evidence on how children and young people are affected, and even less discussion and evidence on how the climate crisis could affect violence against children.In this commentary, we review selected research to assess the links between the climate crisis and violence against children.We employ a social-ecological perspective as an overarching framework to organize findings from the literature and call attention to increased violence against children as a specific, yet under-examined, direct and indirect consequence of the climate crisis.Using such a perspective, we examine how the climate crisis exacerbates the risk of violence against children at the continually intersecting and interacting levels of society, community, family, and the individual levels. We propose increased risk of armed conflict, forced displacement, poverty, income inequality, disruptions in critical health and social services, and mental health problems as key mechanisms linking the climate crisis and heightened risk of violence against children. Furthermore, we posit that the climate crisis serves as a threat multiplier, compounding existing vulnerabilities and inequities within populations and having harsher consequences in settings, communities, households, and for children already experiencing adversities.We conclude with a call for urgent efforts from researchers, practitioners, and policymakers to further investigate the specific empirical links between the climate crisis and violence against children and to design, test, implement, fund, and scale evidence-based, rights-based, and child friendly prevention, support, and response strategies to address violence against children.