Hydrogen technologies have experienced cycles of excessive expectations followed by disillusion. Nonetheless, a growing body of evidence suggests these technologies form an attractive option for the deep decarbonisation of global energy systems, and that recent improvements in their cost and performance point towards economic viability as well. This paper is a comprehensive review of the potential role that hydrogen could play in the provision of electricity, heat, industry, transport and energy storage in a low-carbon energy system, and an assessment of the status of hydrogen in being able to fulfil that potential. The picture that emerges is one of qualified promise: hydrogen is well established in certain niches such as forklift trucks, while mainstream applications are now forthcoming. Hydrogen vehicles are available commercially in several countries, and 225 000 fuel cell home heating systems have been sold. This represents a step change from the situation of only five years ago. This review shows that challenges around cost and performance remain, and considerable improvements are still required for hydrogen to become truly competitive. But such competitiveness in the medium-term future no longer seems an unrealistic prospect, which fully justifies the growing interest and policy support for these technologies around the world.

https://pubs.rsc.org/en/content/articlepdf/2019/ee/c8ee01157e

The role of hydrogen and fuel cells in the global energy system

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

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

This paper describes a new approach to online forecasting of power production from PV systems. The method is suited to online forecasting in many applications and in this paper it is used to predict hourly values of solar power for horizons of up to 36 h. The data used is 15-min observations of solar power from 21 PV systems located on rooftops in a small village in Denmark. The suggested method is a two-stage method where first a statistical normalization of the solar power is obtained using a clear sky model. The clear sky model is found using statistical smoothing techniques. Then forecasts of the normalized solar power are calculated using adaptive linear time series models. Both autoregressive (AR) and AR with exogenous input (ARX) models are evaluated, where the latter takes numerical weather predictions (NWPs) as input. The results indicate that for forecasts up to 2 h ahead the most important input is the available observations of solar power, while for longer horizons NWPs are the most important input. A root mean square error improvement of around 35% is achieved by the ARX model compared to a proposed reference model.

/pdf/online-short-term-solar-power-forecasting-1ljgpbshkb.pdf

Online Short-term Solar Power Forecasting

A review of more than 60 studies (plus m4ore than 65 studies on P2G) on power and energy models based on simulation and optimization was done. Based on these, for power systems with up to 95% renewables, the electricity storage size is found to be below 1.5% of the annual demand (in energy terms). While for 100% renewables energy systems (power, heat, mobility), it can remain below 6% of the annual energy demand. Combination of sectors and diverting the electricity to another sector can play a large role in reducing the storage size. From the potential alternatives to satisfy this demand, pumped hydro storage (PHS) global potential is not enough and new technologies with a higher energy density are needed. Hydrogen, with more than 250 times the energy density of PHS is a potential option to satisfy the storage need. However, changes needed in infrastructure to deal with high hydrogen content and the suitability of salt caverns for its storage can pose limitations for this technology. Power to Gas (P2G) arises as possible alternative overcoming both the facilities and the energy density issues. The global storage requirement would represent only 2% of the global annual natural gas production or 10% of the gas storage facilities (in energy equivalent). The more options considered to deal with intermittent sources, the lower the storage requirement will be. Therefore, future studies aiming to quantify storage needs should focus on the entire energy system including technology vectors (e.g. Power to Heat, Liquid, Gas, Chemicals) to avoid overestimating the amount of storage needed.

/pdf/a-review-at-the-role-of-storage-in-energy-systems-with-a-3pe9h4h281.pdf

A review at the role of storage in energy systems with a focus on Power to Gas and long-term storage

Due to different viewpoints, procedures, limitations, and objectives, the scheduling problem of distributed energy resources (DERs) is a very important issue in power systems. This problem can be solved by considering different frameworks. Microgrids and Virtual Power Plants (VPPs) are two famous and suitable concepts by which this problem is solved within their frameworks. Each of these two solutions has its own special significance and may be employed for different purposes. Therefore, it is necessary to assess and review papers and literature in this field. In this paper, the scheduling problem of DERs is studied from various aspects such as modeling techniques, solving methods, reliability, emission, uncertainty, stability, demand response (DR), and multi-objective standpoint in the microgrid and VPP frameworks. This review enables researchers with different points of view to look for possible applications in the area of microgrid and VPP scheduling.

A comprehensive review on microgrid and virtual power plant concepts employed for distributed energy resources scheduling in power systems

Effects of large-scale power to gas conversion on the power, gas and carbon sectors and their interactions

A comparative study of imbalance reduction strategies for virtual power plant operation

The impact of small scale cogeneration on the gas demand at distribution level

Smart grids are considered important building blocks of a future energy system that facilitates integration of massive distributed energy resources like gas-fired cogeneration (CHP). The latter produces thermal and electric power together and as such reinforces the interaction between the gas and electricity-distribution systems. Thermal storage makes up the key-source of flexibility that allows decoupling the electricity production from the heat demand. However, smart grids focus on electricity, often disregarding the role of gas and thermal storage in overall smart energy systems. We find that the technical impact of a massive introduction of CHP on the gas-distribution network is limited in most cases, even providing opportunities to free up capacity. Taking the consumer's viewpoint, we highlight the economic importance of the thermal storage tank, which requires a thermal capacity of two to three times the hourly thermal power output of the CHP to optimize electric power production and limit thermal losses. Further increasing the storage tank size can increase the gas-distribution capacity that can be marketed by the distribution system operator, but practical constraints in terms of dedicated land area have to be considered as well.

/pdf/the-role-of-thermal-storage-and-natural-gas-in-a-smart-1nj62nc2mk.pdf

Jeroen Vandewalle

Papers

Effects of large-scale power to gas conversion on the power, gas and carbon sectors and their interactions

A comparative study of imbalance reduction strategies for virtual power plant operation

The impact of small scale cogeneration on the gas demand at distribution level

The role of thermal storage and natural gas in a smart energy system

The Role of Thermal Storage and Natural Gas in a Smart Energy System