▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Mitigation and Adaptation Strategies for Global Change

https://publikationen.bibliothek.kit.edu/1000050288/18451059

Renewable Power-to-Gas: A technological and economic review

Due to increasing concerns about global warming, greenhouse gas emissions, and the depletion of fossil fuels, the electric vehicles (EVs) receive massive popularity due to their performances and efficiencies in recent decades. EVs have already been widely accepted in the automotive industries considering the most promising replacements in reducing CO2 emissions and global environmental issues. Lithium-ion batteries have attained huge attention in EVs application due to their lucrative features such as lightweight, fast charging, high energy density, low self-discharge and long lifespan. This paper comprehensively reviews the lithium-ion battery state of charge (SOC) estimation and its management system towards the sustainable future EV applications. The significance of battery management system (BMS) employing lithium-ion batteries is presented, which can guarantee a reliable and safe operation and assess the battery SOC. The review identifies that the SOC is a crucial parameter as it signifies the remaining available energy in a battery that provides an idea about charging/discharging strategies and protect the battery from overcharging/over discharging. It is also observed that the SOC of the existing lithium-ion batteries have a good contribution to run the EVs safely and efficiently with their charging/discharging capabilities. However, they still have some challenges due to their complex electro-chemical reactions, performance degradation and lack of accuracy towards the enhancement of battery performance and life. The classification of the estimation methodologies to estimate SOC focusing with the estimation model/algorithm, benefits, drawbacks and estimation error are extensively reviewed. The review highlights many factors and challenges with possible recommendations for the development of BMS and estimation of SOC in next-generation EV applications. All the highlighted insights of this review will widen the increasing efforts towards the development of the advanced SOC estimation method and energy management system of lithium-ion battery for the future high-tech EV applications.

A review of lithium-ion battery state of charge estimation and management system in electric vehicle applications: Challenges and recommendations

The uncontrolled discharge of large amounts of food waste (FW) causes severe environmental pollution in many countries. Within different possible treatment routes, anaerobic digestion (AD) of FW into biogas, is a proven and effective solution for FW treatment and valorization. The present paper reviews the characteristics of FW, the principles of AD, the process parameters, and two approaches (pretreatment and co-digestion) for enhancing AD of food waste. Among the successive digestion reactions, hydrolysis is considered to be the rate-limiting step. To enhance the performance of AD, several physical, thermo-chemical, biological or combined pretreatments are reviewed. Moreover, a promising way for improving the performance of AD is the co-digestion of FW with other organic substrates, as confirmed by numerous studies, where a higher buffer capacity and an optimum nutrient balance enhance the biogas/methane yields of the co-digestion system.

Reviewing the anaerobic digestion of food waste for biogas production

To improve the sustainability of transportation, a major goal is the replacement of conventional petroleum-based fuels with more sustainable fuels that can be used in the existing infrastructure (fuel distribution and vehicles). While fossil-derived synthetic fuels (e.g. coal derived liquid fuels) and biofuels have received the most attention, similar hydrocarbons can be produced without using fossil fuels or biomass. Using renewable and/or nuclear energy, carbon dioxide and water can be recycled into liquid hydrocarbon fuels in non-biological processes which remove oxygen from CO2 and H2O (the reverse of fuel combustion). Capture of CO2 from the atmosphere would enable a closed-loop carbon-neutral fuel cycle. This article critically reviews the many possible technological pathways for recycling CO2 into fuels using renewable or nuclear energy, considering three stages—CO2 capture, H2O and CO2 dissociation, and fuel synthesis. Dissociation methods include thermolysis, thermochemical cycles, electrolysis, and photoelectrolysis of CO2 and/or H2O. High temperature co-electrolysis of H2O and CO2 makes very efficient use of electricity and heat (near-100% electricity-to-syngas efficiency), provides high reaction rates, and directly produces syngas (CO/H2 mixture) for use in conventional catalytic fuel synthesis reactors. Capturing CO2 from the atmosphere using a solid sorbent, electrolyzing H2O and CO2 in solid oxide electrolysis cells to yield syngas, and converting the syngas to gasoline or diesel by Fischer–Tropsch synthesis is identified as one of the most promising, feasible routes. An analysis of the energy balance and economics of this CO2 recycling process is presented. We estimate that the full system can feasibly operate at 70% electricity-to-liquid fuel efficiency (higher heating value basis) and the price of electricity needed to produce synthetic gasoline at U.S.D$ 2/gal ($ 0.53/L) is 2–3 U.S. cents/kWh. For $ 3/gal ($ 0.78/L) gasoline, electricity at 4–5 cents/kWh is needed. In some regions that have inexpensive renewable electricity, such as Iceland, fuel production may already be economical. The dominant costs of the process are the electricity cost and the capital cost of the electrolyzer, and this capital cost is significantly increased when operating intermittently (on renewable power sources such as solar and wind). The potential of this CO2 recycling process is assessed, in terms of what technological progress is needed to achieve large-scale, economically competitive production of sustainable fuels by this method.

Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy

Biogas is a relatively mature renewable energy technology but still most commercial biogas power plants require significant financial incentives. Additionally, local shortages of very cheap digestible feedstocks limit biogas productivity, especially for larger biogas power plants (>1 MWe). Innovations that could improve cost-effectiveness and resource efficiency of biogas energy technology are therefore required. Over the last few years a number of potential process innovations for biogas technology have been proposed and investigated. However, the majority of these novel concepts has minimal or no impact on technology development. Disruptive innovations are very rare, but only they really matter for the economy. Therefore review reports that systematically compare, analyze and evaluate the suitability of these emerging methods with emphasis on technological excellence and realistic commercial potential are needed. This study presents potential process innovations from most recent patent and academic literature proposed for biogas (i) production, (ii) conditioning, (iii) utilization and (iv) industrial symbiosis. Within these four highly interdisciplinary categories the review attempts to provide short practical comments on selected methods and briefly analyzes their perspectives and constraints. Further, relevant biogas process innovation criteria are designed and multiple-criteria assessment of pre-selected potential process innovations is made. The paper concludes with the characterization of innovativeness of selected solutions and suggests future research needs for biogas energy technology that could bring new innovations in near term.

A review of potential innovations for production, conditioning and utilization of biogas with multiple criteria assessment

The article investigates prospects and challenges for expanding of sustainable biogas energy in Poland. The number of Polish biogas fuelled power plants and installed electrical power during the 2001–2010 decade is presented. Current economical incentives for biogas energy are discussed. It is emphasized that some revisions to the Polish tradable certificate system are urgently needed in order to encourage energy crop cultivation and the use of best available power technologies. Further, promising, but mostly unexplored feedstocks, such as energy crops, grasses and sorted municipal organic wastes are analyzed. It is also revealed that agrobiogas is characterized by a unique feature of ‘negative net’ CO2 atmospheric emissions and thus the role of agrobiogas in solving Polish CCS dilemmas is discussed. In regard to biogas energy systems it is stressed, that the cost of electricity from biogas is almost independent on the size of agrobiogas CHP power plants in the range of 0.2–5 MWe. Therefore agrobiogas energy is well suited for distributed energy systems involving small-scale agrobiogas power plants offering more green jobs and improved local waste management characteristics. Finally, reliable technologies suitable for biogas energy conversion and upgrading of biogas fuel to marketable gaseous fuels are briefly characterized.

Sustainable biogas energy in Poland: Prospects and challenges

Economically feasible production of conventional bioenergies such as biofuels, biopower and bioheat is a challenge in biorefineries because they have to compete with inexpensive fossil fuel energies while external production costs are rarely included into the present-day policies. Biomass consists of unique complex chemical structures that cannot be easily artificially synthesized and may be beneficially employed in various practical applications. Therefore, strategies relying on complete biomass disintegration through combustion, gasification or fermentation only to simple usable bioenergies do not lead to optimal utilization of biomass feedstock. Instead, cascading approaches are required in order to maximize biomass valorization. Consequently, high-value low-volume bioproducts coupled to bioenergies with potential to improve economic viability of biorefineries and biomass resource utilization are urgently required. Integrated production of bioenergies and bioproducts may be achieved by coupling existing biofuel plants with new bioindustries, by retrofitting existing bioindustries with new bioenergy facilities or by erecting completely new integrated facilities. The current paper reviews literature and provides systematized insights into various high-value low-volume bioproducts coupled to bioenergies in biorefinery contexts. It analyses potential benefits of a range of such bioproducts and gives comments on associated business development. The review thus creates foundations for more thoughtful design procedures of economically feasible sustainable biorefineries that could meet technical and market requirements and improve cascading biomass utilization. Owing to insufficient technology readiness the study also aims at improved understanding of major technological gaps limiting expanded economically viable utilization of high-value bioproducts through biorefineries. It is emphasized that the major advantage of biorefineries is their suitability for maximizing valorization of structural and energetic potentials lying in biomass. The study suggests that new business models introducing high-value bioproducts to biorefineries are essential for achieving economic viability of industries within bioeconomy.

High-value low-volume bioproducts coupled to bioenergies with potential to enhance business development of sustainable biorefineries

Conventional fossil fuel-based energy technologies can achieve efficiency in energy conversion but they are usually completely inefficient in carbon conversion because they generate significant CO2 emissions to the atmosphere per unit energy converted. In contrast, some renewable energy technologies characterized by negative carbon intensity can simultaneously achieve efficiency in the conversion of energy and in the conversion of carbon. These carbon negative renewable energy technologies can generate useful energy and remove CO2 from the atmosphere, either by direct capture and recycling of atmospheric CO2 or indirectly, by involving biofuels. Interestingly, the deployment of carbon negative renewable energy technologies can offset carbon emissions from conventional fossil fuel-based energy technologies and thus reduce the overall carbon intensity of energy systems. The current review analyzes two groups of renewable energy technologies involving biomass or CO2 as inputs. The discussions focus on useful techniques which enable to achieve negative carbon intensity of energy while being technologically promising in near-term as well as cost-effective. These analyzes include advanced carbon sequestration concepts such as soil carbon sequestration and CO2 recycling to useful C-rich products such as fuels and fertilizers. The 'drop-in' of renewable energy is achieved by allowing bioenergy and renewable energies in the form of renewable electricity, renewable thermal energy, solar energy, renewable hydrogen, etc. The carbon negative renewable energy technologies are analyzed and perspectives and constraints of each technology are expounded.

Wojciech M. Budzianowski

Papers

A review of potential innovations for production, conditioning and utilization of biogas with multiple criteria assessment

Sustainable biogas energy in Poland: Prospects and challenges

High-value low-volume bioproducts coupled to bioenergies with potential to enhance business development of sustainable biorefineries

Negative carbon intensity of renewable energy technologies involving biomass or carbon dioxide as inputs

Power requirements of biogas upgrading by water scrubbing and biomethane compression: comparative analysis of various plant configurations