Energy recovery from waste treatment and growing biomass is of great significance for the energy management and sustainable energy supply. It is shown that biomass and various wastes containing carbon are able to significantly contribute to the energy sector.

We describe a possible scenario for the energy development of an European country of the future. In addition to solar, wind, and hydrogen energy, priority should also be given to generating energy using small-sized gasifiers. First, it is sustainable energy since biomass and household waste are always available. Second, this approach will allow us to launch local electric power grids instead of the unified state and interstate grids, which will reduce up to three times the consumption of energy raw materials and financial resources. Third, a new design of electric motors, namely torus motors, will allow one almost halve electricity consumption and open a gateway to new technologies.

Circular energy transformation of Turkey is essential to strengthen the national energy security. Turkey will benefit from moving towards a circular economy.

Circular economy (CE) has gained much attention due to global warming and climate change which are the most serious issues faced in the world. The United Nations has been struggling with the issues regarding sustainable development by releasing some programs and legislations, which are mostly supported by the EU. The EU's CE including both economy and energy within the scope of low-carbon world is binding for Turkey's energy transition. Among renewables, solar energy preserved the leading capacity expansion with an increase of 98 GW in 2019 in the world. Solar photovoltaic (PV) has become a mainstream energy source among renewables. Since the PV installation has been growing all around the world, several countries especially China, Germany, and the UK pay special attention to a sustainable PV waste management concept. We present the special case of Turkey within the global CE along with the current status of renewable energy in the global energy transformation. Turkey's energy outlook and the EU's targets are reviewed, and the significant role of solar energy in the CE transition process of Turkey has been revealed. We suggested adding a vision of “More Circular” to her new energy policy “More Domestic, More Renewable.”

The circular economy aspects of PET (polyethylene terephthalate) waste conversion into value-added products are discussed concerning different governmental policies and industrial protocol for plastic degradation.

The use of microbial enzymes such as PET hydrolase is discussed regarding PET (polyethylene terephthalate) degradation.

The primary purpose of this perspective is a critical analysis of the correlation of the current state-of-the-art rising circular economy platform enacted across the world with close looping of PET (polyethylene terephthalate)-based plastic polymer disposal and sustainable recycling and upcycling technology. The goal of the upcycling process is to get the low-cost value-added monomer than those obtained from the hydrocarbon industry from the sustainability prospect. A summary of the circular bio-economic opportunities has also been described. Next, how the PET hydrolase enzyme degrades the PET plastic is discussed. It is followed by an additional overview of the effect of the mutant enzyme for converting 90% of plastics into the terephthalate monomer. A site-directed mutagenesis procedure obtains this particular mutant enzyme. The diversity of different microbial organism for producing PET hydrolase enzyme is finally discussed with a suggested outlook of the circular economy goal from the viewpoint of plastic degradation objectives soon.

The sustainable integration of human activities into the global ecosystem is discussed, pointing out fatal anthropogenic heat as a major ecological problem and proposing global technical and economical solutions.

For human sake, we must get out of the “thermal age” and implement the “electroprotonic era” as soon as possible. Contrary to thermal power, electroprotonic is sustainable and can be produced by photoenzymatic systems, a cheap way to produce hydrogen (H2) or ammonia (NH3). We can accelerate the advent of this new era if we re-integrate external costs generated by thermal energies into their final prices. The author is leading the H2GREEN project in Belgium as an entrepreneur for more than a decade, which develops the photoenzymatic production of dihydrogen from water. The aim of the H2GREEN project is to contribute to the launch of a low-cost, renewable Hydrogen-based local economy as an energy carrier. Among the difficulties of this launch, the most important is certainly the lack of competitiveness due to the unfair competition of carbon products that externalizes their costs (CO2, oil spills, lethal pollution, armed conflicts, political oppression, foreign dependence, etc.).

Role of MOFs in CO2 chemical conversion; Photocatalytic and electrocatalytic CO2 reduction; Role of linkers and metals in CO2 chemical conversion; and MOF composites and films in CO2 conversion.

In this review, we analyze the emerging field of metal–organic frameworks (MOFs) as catalysts for chemical conversion of CO2, with examples ranging from heterogeneous CO2 organic transformation to heterogeneous CO2 hydrogenation, from photocatalytic to electrocatalytic CO2 reduction. We also discuss the role of MOF composites and films in CO2 transformation. Our goal is to have an instrument useful to identify the best MOFs for CO2 conversion.

A comparison between electrochemical carbon dioxide conversion and reforestation is presented. By comparing thermodynamic and forestry data, recommendations for technology development can be made.

With the global average temperature steadily increasing due to anthropogenic emission of greenhouse gases into the atmosphere, there has been increasing interest worldwide in new technologies for carbon capture, utilization, and storage (CCUS). This coincides with the decrease in cost of deployment of intermittent renewable electricity sources, specifically solar energy, necessitating development of new methods for energy storage. Carbon dioxide conversion technologies driven by photovoltaics aim to address both these needs. To adequately contribute to greenhouse gas reduction, the carbon dioxide conversion technology deployed should have a substantially higher rate of carbon dioxide removal than planting an equivalent-sized forest. Using consistent methodologies, we analyze the effectiveness of model photovoltaic-driven carbon dioxide conversion technologies that produce liquid alcohols as compared to planting an equivalent forest. This analysis serves to establish an energy use boundary for carbon dioxide conversion technology, in order to be a viable alternative as a net carbon negative technology.

Hydrogen is often touted as the fuel of the future, but hydrogen is already an important feedstock for the chemical industry. This review highlights current means for hydrogen production and use, and the importance of progressing R&D along key technologies and policies to drive a cost reduction in renewable hydrogen production and enable the transition of chemical manufacturing toward green hydrogen as a feedstock and fuel.

The chemical industry is at the core of what is considered a modern economy. It provides commodities and important materials, e.g., fertilizers, synthetic textiles, and drug precursors, supporting economies and more broadly our needs. The chemical sector is to become the major driver for oil production by 2030 as it entirely relies on sufficient oil supply. In this respect, renewable hydrogen has an important role to play beyond its use in the transport sector. Hydrogen not only has three times the energy density of natural gas and using hydrogen as a fuel could help decarbonize the entire chemical manufacturing, but also the use of green hydrogen as an essential reactant at the basis of many chemical products could facilitate the convergence toward virtuous circles. Enabling the production of green hydrogen at cost could not only enable new opportunities but also strengthen economies through a localized production and use of hydrogen. Herein, existing technologies for the production of renewable hydrogen including biomass and water electrolysis, and methods for the effective storage of hydrogen are reviewed with an emphasis on the need for mitigation strategies to enable such a transition.

Energy, water, and food shortages, along with irreversible environmental damage and climate changes, are bound to happen within a decade if the current course of action is maintained, preparing the “perfect storm” – a chain of interrelated events that could lead to major stress on the global system.

Energy plays a central role in the complex balance between humankind and the planet: poor strategies for the energy system will lead to disaster; but immediate, radical action can still mitigate what will otherwise be an unprecedented crisis. Reduction of the carbon intensity at the level of primary energy demand is one of the most impactful strategies. Current actions toward this goal, however, including the Nationally Determined Contributions (i.e., the climate actions pledged by the countries that ratified the Paris Agreements), are far from being adequate, and a much stronger effort is required. In this perspective, we draw inspiration from a visionary scientist of the past century, who pioneered the idea of a society powered by solar energy, and show, by a critical presentation of energy and carbon emission data, how this vision is now coming true. We focus our attention in particular to photovoltaics and analyze the factors that make it one of the key energy sources for the short and for the long term: economical convenience, the opening of very large markets, and the push by key players of the energy system.

Detailed report on MOFs for CO2 adsorption on the basis of ligands employed, OMSs, and structures. Systematic report on the high- and low-pressure CO2 capture. Report on the mechanism of CO2 capture.

A review on the promising field of MOF-based carbon capture and storage is presented. We discuss here the main features of MOFs applicable for CO2 capture and separation, the linker functionalization role, and the most important CO2-binding sites as also the most efficient and significant technologies, and a systematic report on the high- and low-pressure CO2 capture.

Environmental concerns deriving from fossil fuel dependency are driving an energy transition based on sustainable processes to make fuels and chemicals. Solar hydrogen is the pillar of this new green economy, but the technological readiness level of PV electrolysis and direct photoelectrochemical (PEC) electrolysis are still too low to allow broad commercialization. Direct conversion through PEC technology has more potential in the medium–long term but must be first guided by the scientific enhancements to improve device efficiencies. For this purpose, in situ and operando photoelectrochemistry will guide the discovery of new materials and processes to make solar fuels and chemicals in PEC cells.

The use of advanced in situ and operando characterizations under working photoelectrochemical (PEC) conditions is reviewed here and anticipated to be a fundamental tool for achieving a basic understanding of new PEC processes and for enabling the large-scale development of PEC technology by 2050, thus delivering fuels and chemicals having zero (or negative) carbon footprint. Hydrogen from solar water splitting is the most popular solar fuel and can be mainly produced by indirect photovoltaic-driven electrolysis (PV electrolysis) and direct photoelectrochemistry. Although PV electrolysis has already been developed on a level of MW-scale pilot plants, PEC technology, which is much less mature, holds several advantages in the long term over PV-electrolysis systems. The key enabling feature to developing PEC technology is the improvement of the photoelectrode materials which are responsible for the absorption of light, and transport of the photo-generated charge carriers to drive the electrochemical surface reaction. These processes are often complex and multistep, spanning multiple timescales and following the simultaneous detection of photoelectrodes modification and formation of reaction intermediates/products can be achieved using eight well-known characterization techniques here presented.

A liquid-state pyroelectric energy harvester is described and a remarkable capacity to convert a thermal gradient into electrical energy is demonstrated.

Increasing the sustainability of energy generation can be pursued by harvesting extremely low enthalpy sources: low temperature differences between cold and hot reservoirs are easily achieved in every industrial process, both at large and small scales, in plants as well as in small appliances, vehicles, natural environments, and human bodies. This paper presents the assessment and efficiency estimate of a liquid-state pyroelectric energy harvester, based on a colloid containing barium titanate nanoparticles and ferrofluid as a stabilizer. The liquid is set in motion by an external pump to control velocity, in a range similar to the one achieved by Rayleigh–Bénard convection, and the colloid reservoir is heated. The colloid is injected into a Fluorinated Ethylene Propylene pipe where titanium electrodes are placed to collect electrical charges generated by pyroelectricity on the surface of the nanoparticles, reaching 22.4% of the ideal Carnot efficiency of a thermal machine working on the same temperature drop. The maximum extracted electrical power per unit of volume is above 7 mW/m3 with a ΔT between electrodes of 3.9 K.

The electrification of organic syntheses is a vividly growing research field and has attracted tremendous attention by the chemical industry. This review highlights aspects of electrosynthesis that are rarely addressed in other articles on the topic: the energy consumption and energy efficiency of technically relevant electro-organic syntheses.

Four examples on different scales are outlined.

Electro-organic synthesis has experienced a renaissance within the past years. This review addresses the energy efficiency or energy demand of electrochemically driven transformations as it is a key parameter taken into account by, for example, decision makers in industry. The influential factors are illustrated that determine the energy efficiency and discussed what it takes for an electrochemical process to be classified as “energy efficient.” Typical advantages of electrosynthetic approaches are summarized and characteristic aspects regarding the efficiency of electro-organic processes, such as electric energy consumption, are defined. Technically well-implemented examples are described to illustrate the possible benefits of electrochemical approaches. Further, promising research examples are highlighted and show that the conversion of fine chemicals is rather attractive than the electrochemical generation of synthetic fuels.