• Energy Research
• 7. Clean energy close
• 6. Clean water close
• 8. Economic growth close
• KR close

The ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia). We asked whether the 4 per mille initiative is feasible for the region. The outcomes highlight region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates globally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha− 1), and at the first twenty years after implementation of best management practices. In addition, areas which have reached equilibrium will not be able to further increase their sequestration. We found that most studies on SOC sequestration only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille number was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille in the top 1m of global agricultural soils, SOC sequestration is between 2-3 Gt C year− 1, which effectively offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become viable. The challenge for cropping farmers is to find disruptive technologies that will further improve soil condition and deliver increased soil carbon. Progress in 4 per mille requires collaboration and communication between scientists, farmers, policy makers, and marketeers.

AbstractA novel multifunctional conjugated polymer (RCP‐1) composed of an electron‐donating backbone (carbazole) and an electron‐accepting side chain (cyanoacetic acid) connected through conjugated vinylene and terthiophene has been synthesized and tested as a photosensitizer in two major molecule‐based solar cells, namely dye sensitized solar cells (DSSCs) and organic photovoltaic cells (OPVs). Promising initial results on overall power conversion efficiencies of 4.11% and 1.04% are obtained from the basic structure of DSSCs and OPVs based on RCP‐1, respectively. The well‐defined donor (D)‐acceptor (A) structure of RCP‐1 has made it possible, for the first time, to reach over 4% of power conversion efficiency in DSSCs with an organic polymer sensitizer and good operation stability.

One of main concepts involved in regional small nuclear reactors is unmanned remote control. Internet-based virtual private networks provide environments for the remote monitoring and control of geographically-dispersed systems, and with the advances in communication technologies, the potential of networks for real time control and automation becomes enormous. However, networked control has some problems. The most critical is delay in signal transmission, which degrades system stability and performance. Therefore, a networked control system should be designed to account for delay. This paper proposes some design approaches for a delay-tolerant system that can guarantee predetermined stability margins and performance. To accomplish this, the reactor plant is modeled with consideration of uncertainties. With this model, three kinds of controllers are developed using different methods. The designed systems are compared with respect to stability and performance, and a second-order controller designed using the table lookup method was found to give the most satisfactory results.

Abstract Energy harvesting in natural environment has attracted a great deal of attention to generate stable and continuous electrical energy. In this work, we proposed an advanced pyroelectric energy harvesting system by using form-stable phase change material (PCM) composites. The PCM composite connected pyro-electrode generated electrical polarization due to the change of external environment. Polyethylene glycol (PEG) and 1-tetradecanol (1-TD) composites with different phase transition field induced the temperature difference during light-on/-off process. Poly(vinylidene difluoride) (PVDF) was utilized for pyroelectric energy harvesting. The PVDF based pyro-electrode was applied changing the conditions of solar light irradiation and heat air flow. The PCM composites controlled the temperature fluctuation effectively and generated stable output electrical voltage and current. Numerical simulation was carried out to provided in-depth insight into the underlying physics of the system. We envisage that the developed thermal energy harvesting system can pave a way towards high-throughput and sustainable energy harvesting.

Abstract In this work, earth-abundant CZTSSe thin film solar cells were fabricated by sulfo-selenization of the Mo/Zn/Cu/Sn/Cu metallic precursors. The influences of morphological and compositional properties of the absorbers on performance of solar cells were investigated by tuning Cu content in the films. The Raman analysis showed that absorbers consist of a kesterite CZTSSe phase with ZnSe as a minor secondary phase. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surfaces are Cu depleted and Zn enriched compared with the bulk composition of the absorbers. The results indicate that during sulfo-selenization the Cu diffused into the film and the Zn towards the film surface. The performance of the solar cells initially improved with the increasing of the Cu content and then decreased. By tuning the Cu content in the absorbers, the minority-carrier life time improved from 0.8 to 1.6 ns. The power conversion efficiency increased from 5.1 to 8.03% with fine controlling of Cu composition of the CZTSSe absorbers. The diode-ideality factors are higher than 2, suggesting an increased interfacial recombination in the devices. The high ideality-factors A and low minority carrier life times may originate from surface and bulk related defects, which in turn limits the Voc and the achievable high conversion efficiency for the CZTSSe thin film solar cells.

The combustion possibility of Indonesia KBB coal as a pulverized fuel for a thermal power plant was studied with a thermogravimetric analysis (TGA), drop tube furnace (DTF) and ignition temperature (IT) tester. TGA results showed that combustion patterns of coal samples were divided into devolatilization and oxidation reactions, and the fixed carbon contained with minor content in high moisture KBB coal (HM KBB) was quickly burned at a lower temperature than that of bituminous C&A coal (Design C&A). The linear regression for the Arrhenius plot to the experimental data is very good, and activation energies for overall combustion of Design C&A and HM KBB are 63.19 and 81.89 kJ/mol, respectively. It was derived that activation energies of dry KBB coal (Dry KBB) produced through drying of HM KBB and its mixture (Dry KBB Mixture) are 79.82 and 61.66 kJ/mol in reciprocal proportion to specific surface area. Test results show that the volatile content contained in coal samples except for HM KBB with the lowest surface area significantly improved the combustion reactivity. The conversion behavior of the coals observed in DTF was similar to that reflected in TGA. DTF studies showed that the combustion of Dry KBB Mixture was also completed at a residence time of around 1 s and set temperature range of 1,200°C similar to commercial coal fired plant. Although Dry KBB has the highest conversion of the four coals, it was not appropriate as a single pulverized fuel of coal fired plant because its initial deformation (IDT) and ignition temperatures of about 1,088 and 198°C, respectively, were too low to cause slagging in boiler, and firing at the pulverizer. The high IDT of Dry KBB Mixture ash with minimum of 1,250°C is not expected to be associated with slagging and fouling in pulverized coal fired systems. The liability of spontaneous combustion of coal samples was increased with increasing the moisture and volatile contents whereas that of Dry KBB was the highest due to the high surface area. It was, therefore, proposed that the combustion of mixtures of Dry KBB with Design C&A was the most appropriate for the prevention of slagging and spontaneous combustion in pulverized coal fired boilers and has excellent combustion efficiency.

Torrefaction is a thermal treatment process to pre-treat biomass at temperature of under an inert atmosphere. It was known that torrefaction process strongly depended on the decomposition temperature of the lignocellulosic constituents in biomass. In this work, the torrefaction characteristics of baggase has been studied. This study focuses on the relation between the energy yields, heating values, gas emission, volatile and ash constituents with torrefaction temperatures and times. The activation energies of baggase torrefaction has been studied by using TGA (Thermogravimetric Analyzer). From this work, it was seen that ash constituents and heating values were increased with torrefaction temperature, while volatile constituents and energy yields decreased. It was also found that carbon monoxide containing oxygen were decomposed at a lower temperature than those of hydrocarbon compounds, .