• Energy Research

With the expansion of renewable energy's contribution to the energy mix, balancing the electricity grid is becoming increasingly challenging. Alongside other solutions, Power-to-Hydrogen concepts are gaining significant interest. In this paper, the “Task 38”, initiated by the Hydrogen Implementing Agreement of the International Energy Agency, presents the first of a two-step literature review regarding Power-to-Hydrogen and Hydrogen-to-X concepts with a focus on prospective market and economic potential. The study reveals a large scope of literature that shows a considerable variety of suggested implementation schemes. The transportation sector is identified as the most promising consumer market. Hydrogen-to-Gas pathways will require subsidies in order to be profitable. Hydrogen-to-Power becomes an economically promising option in the context of systems with high shares of renewables and a need for longer-term storages. Additionally, key enablers for Power-to-Hydrogen concepts are identified; namely support policies, concurrently with ongoing progress on the development and implementation of industry standard.

With the expansion of renewable energy's contribution to the energy mix, balancing the electricity grid is becoming increasingly challenging. Alongside other solutions, Power-to-Hydrogen concepts are gaining significant interest. In this paper, the “Task 38”, initiated by the Hydrogen Implementing Agreement of the International Energy Agency, presents the first of a two-step literature review regarding Power-to-Hydrogen and Hydrogen-to-X concepts with a focus on prospective market and economic potential. The study reveals a large scope of literature that shows a considerable variety of suggested implementation schemes. The transportation sector is identified as the most promising consumer market. Hydrogen-to-Gas pathways will require subsidies in order to be profitable. Hydrogen-to-Power becomes an economically promising option in the context of systems with high shares of renewables and a need for longer-term storages. Additionally, key enablers for Power-to-Hydrogen concepts are identified; namely support policies, concurrently with ongoing progress on the development and implementation of industry standard.

The increasing consumption of coffee worldwide has led to higher amounts of spent coffee grounds (SCG) being produced which are generally disposed of in landfill or used as compost. However, the wide range of molecules present in SCG such as saccharides, lignin, lipids and proteins give this biomass source a large chemical functionality. In this work, SCG were fractionated to separate the components into three separate portions for further valorization; these were hemicellulose-enriched fractions (HEF), lignin-enriched fraction (LEF) and cellulose-enriched fraction (CEF). HEF was effectively used in the growth of the oleaginous yeast Metschnikowia pulcherrima, additionally, the C6 sugars present in this fraction suggests that it can be used in the production of 5-hydroxymethylfurfural (HMF). The LEF had a considerable high heating value (HHV) and would be suitable as a biofuel component for combustion. CEF was efficiently used in the production of HMF as 0.35 g of this product were obtained from 10 g of SCG. Such results demonstrate that SCG can be effectively used in the production of HMF within a biorefinery concept.

The increasing consumption of coffee worldwide has led to higher amounts of spent coffee grounds (SCG) being produced which are generally disposed of in landfill or used as compost. However, the wide range of molecules present in SCG such as saccharides, lignin, lipids and proteins give this biomass source a large chemical functionality. In this work, SCG were fractionated to separate the components into three separate portions for further valorization; these were hemicellulose-enriched fractions (HEF), lignin-enriched fraction (LEF) and cellulose-enriched fraction (CEF). HEF was effectively used in the growth of the oleaginous yeast Metschnikowia pulcherrima, additionally, the C6 sugars present in this fraction suggests that it can be used in the production of 5-hydroxymethylfurfural (HMF). The LEF had a considerable high heating value (HHV) and would be suitable as a biofuel component for combustion. CEF was efficiently used in the production of HMF as 0.35 g of this product were obtained from 10 g of SCG. Such results demonstrate that SCG can be effectively used in the production of HMF within a biorefinery concept.

An effective method for the production of fuels and chemicals from microalgae is to ferment the carbohydrate fraction, extract the lipids and convert the resulting solids through hydrothermal liquefaction (HTL).

An effective method for the production of fuels and chemicals from microalgae is to ferment the carbohydrate fraction, extract the lipids and convert the resulting solids through hydrothermal liquefaction (HTL).

AbstractBiodiesel, the fatty acid methyl ester (FAME) of vegetable and animal oil, is now used extensively worldwide, with blends of up to 7% common. The blending level is still somewhat limited due to a perceived susceptibility of these fuels to oxidation. Oxidation follows a number of pathways, with the primary mechanism being auto‐oxidation, a radical process that results in the production of a range of oxygenated components. These eventually increase the viscosity of the fuel and form deposits detrimental to operation. Further fuel properties are also heavily reliant on the level of oxidation. As such, one of the main challenges in the use of biodiesel is its long‐term instability when stored. Typically synthetic anti‐oxidants have been used to address this issue; however, these systems can also add to the formation of deposits, as well as hazardous emissions, on combustion. Recently, research has focused on novel antioxidant development mainly from plant extracts, although there are a number of other routes for improved performance, including the commercialization of hydrogenated vegetable oil (HVO), a prominent alternative to FAME‐based biodiesel due to its higher stability, straight chain paraffin composition, and better cold flow properties. In this review, the factors that promote this oxidation are presented, including molecular composition, metal contamination, temperature and light exposure, as well as the latest findings on the inclusion of HVO, the current state‐of‐the‐art analytical techniques employed, and the impact of higher pressure injection systems on vehicles that demonstrate deposit formation is not solely due to the unsaturated biodiesel components. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

AbstractBiodiesel, the fatty acid methyl ester (FAME) of vegetable and animal oil, is now used extensively worldwide, with blends of up to 7% common. The blending level is still somewhat limited due to a perceived susceptibility of these fuels to oxidation. Oxidation follows a number of pathways, with the primary mechanism being auto‐oxidation, a radical process that results in the production of a range of oxygenated components. These eventually increase the viscosity of the fuel and form deposits detrimental to operation. Further fuel properties are also heavily reliant on the level of oxidation. As such, one of the main challenges in the use of biodiesel is its long‐term instability when stored. Typically synthetic anti‐oxidants have been used to address this issue; however, these systems can also add to the formation of deposits, as well as hazardous emissions, on combustion. Recently, research has focused on novel antioxidant development mainly from plant extracts, although there are a number of other routes for improved performance, including the commercialization of hydrogenated vegetable oil (HVO), a prominent alternative to FAME‐based biodiesel due to its higher stability, straight chain paraffin composition, and better cold flow properties. In this review, the factors that promote this oxidation are presented, including molecular composition, metal contamination, temperature and light exposure, as well as the latest findings on the inclusion of HVO, the current state‐of‐the‐art analytical techniques employed, and the impact of higher pressure injection systems on vehicles that demonstrate deposit formation is not solely due to the unsaturated biodiesel components. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd