Estonia
Impact of Grid Gas Requirements on Hydrogen Blending Levels
Oct 2021
Publication
The aim of the article is to determine what amount of hydrogen in %mol can be transferred/stored in the Estonian Latvian and Lithuanian grid gas networks based on the limitations of chemical and physical requirements technical requirements of the gas network and quality requirements. The main characteristics for the analysis of mixtures of hydrogen and natural gas are the Wobbe Index relative density methane number and calorific value. The calculation of the effects of hydrogen blending on the above main characteristics of a real grid gas is based on the principles described in ISO 6976:2016 and the distribution of the grid gas mole fraction components from the grid gas quality reports. The Wärtsila methane number calculator was used to illustrate the effects of hydrogen blending on the methane number of the grid gas. The calculation results show that the maximum hydrogen content in the grid gas (hydrogen and natural gas mix) depending on the grid gas quality parameters (methane number gross heat of combustion specific gravity and the Wobbe Index) is in the range of 5–23 %mol H2. The minimum hydrogen content (5 %mol H2) is limited by specific gravity (>0.55). The next limitation is at 12 %mol H2 and is related to the gross heat of combustion (>9.69 kWh/m3). It is advisable to explore the readiness of gas grids and consumers in Estonia Latvia and Lithuania before switching to higher hydrogen blend levels. If the applicability and safety of hydrogen blends above 5 %mol is approved then it is necessary to analyse the possible reduction of the minimum requirements for the quality of the grid gas and evaluate the associated risks (primarily related to specific gravity).
Review of Energy Challenges and Horizons of Hydrogen City Buses
Sep 2022
Publication
This paper discusses fuel cell electric vehicles and more specifically the challenges and development of hydrogen-fueled buses for people accessing this transportation in cities and urban environments. The study reveals the main innovations and challenges in the field of hydrogen bus deployment and identifies the most common approaches and errors in this area by extracting and critically appraising data from sources important to the energy perspective. Three aspects of the development and horizons of fuel cell electric buses are reviewed namely energy consumption energy efficiency and energy production. The first is associated with the need to ensure a useful and sustainable climate-neutral public transport. Herewith the properties of the hydrogen supply of electric buses and their benefits over gasoline gas and battery vehicles are discussed. The efficiency issue is related to the ratio of consumed and produced fuel in view of energy losses. Four types of engines–gasoline diesel gas and electrical–are evaluated in terms of well-to-wheel tank-to-wheel delivery and storage losses. The third problem arises from the production operating and disposal constraints of the society at the present juncture. Several future-oriented initiatives of the European Commission separate countries and companies are described. The study shows that the effectiveness of the FCEBs depends strongly on the energy generation used to produce hydrogen. In the countries where the renewables are the main energy sources the FCEBs are effective. In other regions they are not effective enough yet although the future horizons are quite broad.
Techno-economic Feasibility of Hybrid PV/wind/battery/thermal Storage Trigeneration System: Toward 100% Energy Independency and Green Hydrogen Production
Dec 2022
Publication
With the clear adverse impacts of fossil fuel-based energy systems on the climate and environment ever-growing interest and rapid developments are taking place toward full or nearly full dependence on renewable energies in the next few decades. Estonia is a European country with large demands for electricity and thermal energy for district heating. Considering it as the case study this work explores the feasibility and full potential of optimally sized photovoltaic (PV) wind and PV/wind systems equipped with electric and thermal storage to fulfill those demands. Given the large excess energy from 100% renewable energy systems for an entire country this excess is utilized to first meet the district heating demand and then to produce hydrogen fuel. Using simplified models for PV and wind systems and considering polymer electrolyte membrane (PEM) electrolysis a genetic optimizer is employed for scanning Estonia for optimal installation sites of the three systems that maximize the fulfillment of the demand and the supply–demand matching while minimizing the cost of energy. The results demonstrate the feasibility of all systems fully covering the two demands while making a profit compared to selling the excess produced electricity directly. However the PV-driven system showed enormous required system capacity and amounts of excess energy with the limited solar resources in Estonia. The wind system showed relatively closer characteristics to the hybrid system but required a higher storage capacity by 75.77%. The hybrid PV/wind-driven system required a total capacity of 194 GW most of which belong to the wind system. It was also superior concerning the amount (15.05 × 109 tons) and cost (1.42 USD/kg) of the produced green hydrogen. With such full mapping of the installation capacities and techno-economic parameters of the three systems across the country this study can assist policymakers when planning different country-scale cogeneration systems.
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