• Energy Research
• 2016-2025close
• Closed Access close
• Universidade Católica Portuguesa close

Energy policies in many countries push for an increase in the generation of wind and solar power. Along these developments, the balance between supply and demand becomes more challenging as the generation of wind and solar power is volatile, and flexibility of supply and demand becomes valuable. As a consequence, companies in the electric power sector develop new business models that create flexibility through activities of timing supply and demand. Based on an extensive qualitative analysis of interviews and industry research in the energy industry, the paper at hand explores the role of timing-based business models in the power sector and sheds light on the mechanisms of flexibility creation through timing. In particular we distill four ideal-type business models of flexibility creation with timing and reveal how they can be classified along two dimensions, namely costs of multiplicity and intervention costs. We put forward that these business models offer ‘coupled services’, combining resource-centered and service-centered perspectives. This complementary character has important implications for energy policy.

Abstract To be useful to project managers, real option analysis (ROA) needs to capture the unique characteristics of individual projects and, at the same time, remain tractable and intuitive. That is a challenge since actual projects are often complex, featuring multiple sources of uncertainty as well as multiple investment and operating options. To meet the challenge, ROA has to take a clinical approach to project management and valuation, tailoring its framework to the specifics of each individual project to reflect its main sources of flexibility without becoming overly complex. This paper undertakes a ROA of an offshore oil development project of an integrated oil and gas company. The sequence and interconnections of available real options – exploration options, appraisal options, scaling options and abandonment options – as well as the calibration of the model's parameters, are developed in close collaboration with the Exploration and Production (E&P) division of the company, to assure realism and adherence to what management believes are the key sources of investment flexibility in a typical offshore project. The project assumes that there is joint uncertainty about reserve size and the price of oil. While the first source of uncertainty is resolved through exploration and appraisal activities the second is resolved through a diffusion model. The available real options add a substantial value to the project, with the option to abandon being the most valuable.

Abstract In the last decades, the weight of renewable energies sources (RES-E) in the electricity generation mix of most European countries has considerably increased, constituting an important contribution to the transition towards a low-carbon economy. Until very recently, RES-E were supported by favorable investment mechanisms specially designed to endorse investment in RES-E. More recently, as RES-E are becoming increasingly more competitive (especially wind and solar photovoltaic), RES-E are starting to be remunerated according to market mechanisms. This has generated a lively debate on the economic pros and cons of dispatching RES-E in the market. This paper contributes to this debate by developing a game theoretical model in the context of which we analyze how the inclusion of RES-E in the electricity wholesale market affects equilibrium outcomes under demand and supply uncertainty. Then, we examine how the inclusion of RES-E in the electricity wholesale market impacts firms' incentives to invest in conventional energy sources, characterizing the optimal investment under demand and supply uncertainty. We find that, when RES-E capacity and asymmetry in firms' marginal production costs are sufficiently high, RES-E producers may strategically reduce the market price, in order to evict the less efficient conventional source in that period. Although, in the short-run, this strategy may actually favor energy consumers (since prices are lower), the expectations of inactivity periods (regardless of whether they arise for strategic or market reasons) may negatively affect investment in back-up capacity, possibly leading to an increase in future prices (since less back-up capacity is available). Finally, we provide an analytical characterization of optimal investment levels in conventional energy sources under demand and supply uncertainty.

Abstract In this paper, we analyze the implications of assuming that the intensity of aspirations is endogenous. In accordance with empirical evidence, consumption aspirations decrease with capital accumulation while environmental ones increase. We show that such a change in the intensity of aspirations gives rise to a U-shaped relationship between capital accumulation and environmental quality. We also study the implications of our assumption concerning the optimal allocation and show that the steady-state capital stock can be larger or smaller than the one corresponding to the modified golden rule. In addition, for realistic parameter values, the decentralization of the optimal allocation requires the implementation of a maintenance investment subsidy and a lump-sum transfer from the old to the young generation.

Brewer's spent grain (BSG) is a by-product of the beer industry and a potential source of bioactive compounds. In this study, two methods of extracting bioactive compounds from brewer's spent grain were used - solid-to-liquid conventional extraction (SLE) and solid-to-liquid ohmic heating extraction (OHE) coupled with two ratio combinations of solvents: 60 % and 80 % ethanol:water (v/v). The bioactive potential of the BSG extracts was assessed during the gastrointestinal tract digestion (GID) and the differences in their antioxidant activity, total phenolic content and characterization of the polyphenol profile was measured. The SLE extraction using 60 % ethanol:water (v/v) was the extraction method with higher antioxidant activity (33.88 mg ascorbic acid/g BSG - initial; 16.61 mg ascorbic acid/g BSG - mouth; 15.58 mg ascorbic acid/g BSG - stomach; 17.26 mg ascorbic acid/g BSG - duodenum) and higher content in total phenolics (13.26 mg gallic acid/g BSG - initial; 4.80 mg gallic acid/g BSG - mouth; 4.88 mg gallic acid/g BSG - stomach; 5.00 mg gallic acid/g BSG - duodenum). However, the OHE extraction using 80 % ethanol:water (v/v), had a higher bioaccessibility index (99.77 % for ferulic acid, 72.68 % for 4-hydroxybenzoic acid, 65.37 % for vanillin, 28.99 % for p-coumaric, 22.54 % for catechin) values of polyphenols. All the extracts enhanced (except for SLE for 60 % ethanol:water (v/v) at 2 and 1.5 %, and for 80 % ethanol:water (v/v) at 2 % with Bifidobacterium animalis spp. lactis BB12, where no growth was observed) the growth of the probiotic microorganisms tested (Bifidobacterium animalis B0 - O.D.'s between 0.8240 and 1.7727; Bifidobacterium animalis spp. lactis BB12 - O.D.'s between 0.7219 and 0.8798; Lacticaseibacillus casei 01 - O.D.'s between 0.9121 and 1.0249; and Lactobacillus acidophilus LA-5 - O.D.'s between 0.8595 and 0.9677), demonstrating a potential prebiotic activity of BSG extracts.

Lignocellulosic biomass is the most abundant renewable resource on earth and currently most of this biomass is considered a low-value waste. Specifically, lignin is an underrated bioresource that is mostly burned for energy production and few value-added products have been created. Since the agro-food industry produces large amounts of wastes that can be potential sources of high-quality lignin, scientific efforts should be directed to this industry. Thus, this review provides a systematic overview of the trends and evolution of research on agro-food system-derived lignin (from 2010 to 2020), including the extraction of lignin from various agro-food sources and emergent applications of lignin in the agro-food chain. Crops with the highest average production/year (n = 26) were selected as potential lignin sources. The extraction process efficiency (yield) and lignin purity were used as indicators of the raw material potential. Overall, it is notable that research interest on agro-food lignin has increased exponentially over the years, both as source (567%) and application (128%). Wheat, sugarcane, and maize are the most studied sources and are the ones that render the highest lignin yields. As for the extraction methods used, alkaline and organosolv methods are the most employed (∼50%). The main reported applications are related to lignin incorporation in polymers (∼55%) and as antioxidant (∼24%). Studies on agro-food system-derived lignin is of most importance since there are numerous possible sources that are yet to be fully valorized and many promising applications that need to be further developed.

Grape stalks are lignocellulosic residues that can be valorized through the extraction of lignin - an underutilized biopolymer with high potential. Two lignin extraction methods, alkaline and deep eutectic solvents (DES), were studied, and experimental designs were carried out to obtain the best extraction conditions. The defined parameters for alkaline extraction allowed the recovery of ~48 % of lignin with low purity that was further improved with an autohydrolysis pretreatment (~79 % purity; ~32 % yield). Optimum parameters of DES method rendered high purity lignin (~90 %) without the need of a pretreatment and with a better yield (50.2 % (±2.3)) than the alkaline method. Both lignin fractions presented high antioxidant activities, being close to the antioxidant capacity of BHT for DPPH scavenging. Structural analysis proved the presence of lignin in both alkaline and DES samples with similar morphology. Overall, DES method was more efficient in the extraction of lignin from grape stalks besides its greener and sustainable nature. This work uses DES to extract lignin from this biomass while comparing it with a commonly classical method, proving that grape stalks can be used to extract lignin with a sustainable and efficient method rendering a final ingredient with value-added properties.