Teodoro Gallucci*, Vera Amicarelli*, Giovanni Lagioia*, Paolo Piccinno**, Amedeo Lacalamita**, * Dipartimento di Economia, Management e Diritto dell’Impresa
Università degli Studi di Bari Aldo Moro, Largo Abbazia Santa Scolastica, 53 – 70124 Bari University of Bari Aldo Moro ** P&R Project S.r.l.
e-mail: teodoro.gallucci@uniba.it, vera.amicarelli@uniba.it; giovanni.lagioia@uniba.it p.piccinno@pierreproject.it, a.lacalamita@pierreproject.it
Abstract
Renewable energy plants, such as wind and photovoltaic ones, improve greenhouse gases emissions raising, in the same time, the problem of energy production interruptions because they are not programmable. Especially in renewable plants, production and consume are not aligned in time resulting in overproduction peaks. One possible solution to bypass this problem is hydrogen produced by renewable sources electrolytic cell. The obtained hydrogen is stored in solid form and can be used as zero-emission fuel both in mobility sector and in other industrial sectors (fertilizers, etc.).
The aim of this paper is to highlight the environmental performances generated by hydrogen storage facility located in Troia - Apulia region, through the life cycle assessment (LCA) realized in the framework of a European project titled INGRID (High Capacity Hydrogen Based on green energy storage solutions for network balancing) co-financed by the European Union.
Keywords: hydrogen production, innovation, environmental sustainability
1. Introduction
The growing interest in the use of hydrogen comes from the fact that it can be used both as energy vector and as a fuel, with enormous environmental advantages in terms of pollution. If hydrogen burned with air, it produces water vapour and traces of nitrogen oxides, that is easy to minimize with different technologies; if hydrogen is used with electrochemical systems it produces only water vapour.
In 2010 the worldwide demand of hydrogen was roughly 43 million tons and is foreseen to reach 50 million tons by 2025. “Asia and Pacific are the world’s leading consumers of hydrogen representing 1/3 of the
global consumption; followed by North America and last but not least Western Europe with a 16% of share (7 million tons of H2)” (Fraile, et al., 2015).
Despite the cost of hydrogen being still higher than most fossil fuels, ranging between 10 €/kg - 60 €/kg (Fraile, et al., 2015), its properties allow its use in different application as fuel cells (FCs) in aerospace applications, and in green energy production.
Nowadays, the worldwide production of hydrogen is accomplished by steam reforming of natural gas, by processing crude oil products and coal, as a by-product of the chlor-alkali process or alternative technologies (process or Kvaerner Termocracking).
All these processes have the inconvenient to produce greenhouse gases (GHG), as CO2, gas powder and traces of H2S, even if different techniques in order to improve the purity of hydrogen and to filter and minimize the environmental impacts, have been developed (Cipriani et al, 2014). For this reason several innovative techniques to produce hydrogen from renewable sources (RE) eg. wind, solar, have been studied. According to existing literature, the most important technologies cited for production hydrogen by RE are the following: thermochemical processes from biomass; thermochemical decomposition of water; photo electro-chemical conversion and water electrolysis (Grigoriev S, et al., 2006; Barbir F. 2005, Marshall A, et al., 2007).
Among those, the water electrolysis technology is very promising because recent application studies have improved the hydrogen production efficiency (Ozbilen, et al., 2012; Mazloomi et al, 2012; Tymoczko, et al.
2016). For this reason water electrolysis process can represents the future sustainable hydrogen production system, if electricity used is from renewable sources e.g., wind, solar, hydro (PE International, 2010). A water electrolysis system plays an important role because if renewable energy is available, extra energy may be stored that can be used in FCs to generate electricity or used as a fuel gas for heating applications (Varkaraki, et al 2007, Diogo M. et al 2013). To this a European project, named INGRID (High-capacity hydrogen-based green-energy storage solutions for grid balancing), was funded within the 7th Framework Program (call for ENERGY.2001.7.3-2) “Storage and balancing variable electricity supply and demand" (http://www.ingridproject.eu/).
The starting point of the project was related to the issue of hydrogen energy storage. The energy storage is crucial to balance and integrate large amounts of intermittent renewable energy and improve the efficiency and reliability of the electrical grid. The variable demand of electricity continues to be an obstacle to the spreading of the renewable energy technologies and, for this reason, hydrogen storage can represents a practical way to increase the energy supply emission-free.
One of the main outputs of INGRID project was to build up a demonstrator hydrogen energy storage plant, with a capacity of more than 1 ton of safely stored hydrogen (the largest ever built) consisting of: water electrolyser, solid hydrogen accumulation system, fuel cells and ICT systems for real-time monitoring and control. Exploiting solar and wind energy, the hydrogen produced by the electrolyser in gaseous form is absorbed by magnesium disks, which form stable compounds with hydrogen, called magnesium hydrides, allowing hydrogen to be stored in solid form. The chosen location for building the demonstrator plant was Municipality of Troia in Apulia Region, where over 3.500 MW of solar, wind, and biomass plant are already installed. In the last years, the concentration of renewable energy sources in the municipality of Troia created some problems to the network grid due to both the energy production peaks and to the current insufficient transport capacity of the electrical grids. The aim of this paper is to highlight the environmental performances generated by INGRID demonstrator, through the Life Cycle Assessment (LCA) approach applied to three different usage scenarios.
2. Material and methods
With LCA was possible to assess the global INGRID environmental impacts throughout its life cycle assuming three different usage scenarios: a) production of hydrogen with electrolyser, storage in High Density Storage system (HDS) and hydrogen retransformation into electricity through fuel cells; b) production of hydrogen with electrolyser and its direct injection into the grid to supply vehicles with hydrogen fuel; c) production of hydrogen with electrolyser, storage in HDS, cooling of H2 blocks and their transport to the companies that use hydrogen for their processes.
The system boundaries are from the "cradle to grave", to make comparable the over mentioned three scenarios the functional unit (FU) is 1 kWh needed by INGRID plant and the system's life time is 20 years. The study was conducted in accordance with ISO 14040 and ISO 14044 considering the provisions of the PCR 171 and 173 "Electricity, steam and hot / cold water generation and distribution”.
The study was elaborated using GABI v. 6.6 and Ecoinvent data band v. 3.3 and conducted using primary data for all plant components except for the electrolyser analysed with secondary data included in Ecoinvent v.3.3 appropriately scaled.
The data were collected as results both of site visits and partners interviews using structured “data collection survey” organized in three groups: materials, equipment and wastes.
The results are expressed with the following parameters: Global Warming Potential (GWP) - greenhouse gas emissions expressed in CO2 equivalent; acidification potential - gas emissions expressed as sulphur dioxide equivalent (SO2 is 0,1 part of total chemicals.) and Eutrophication Potential (EP) - emission of substances that contribute to ozone depletion expressed in phosphate equivalent.
2.1 Plant description
Before illustrating the LCA results a brief description of the plant is reported. INGRID demonstrator is composed by (see figure 1):
- a water electrolyser, powered by RE produced in Apulia region (with the energy mix equal to 50% photovoltaic and 50% wind) consisting of 4 sub-modular units (300 kW each one) and connected in parallel separating pure O2 gas and H2;
- HDS which consists of 4 filling stations (150 kW each) absorbing and storing all the H2 obtained in solid form for subsequent use;
- 4 FCs sub-units (30 kW each), connected directly with the HDS storage unit able to convert H2 into electricity.
Figure 1: Ingrid demonstrator plant flow diagram
Source: personal elaboration of the authors
According to the LCA, INGRID plant is split in upstream, core and down stream phases. The upstream phase concerns:
- creation of all components from the extraction of raw materials to the assembly in the production site of each supplier;
- plant site built up in Troia municipality;
- transport phase and installation of components at site of Troia;
The core phase refers to the usage phase of the three different scenarios.
- Scenario 1: production of hydrogen with electrolyser, storage in HDS and hydrogen retransformation into electricity through fuel cells. The production cycle is 4 days (omitted the characteristics of distribution grid);
- Scenario 2: production of hydrogen with electrolyser and its direct injection into the grid to supply vehicles with hydrogen fuel (omitted the impact of construction of hydrogen system to the vehicles). The production cycle is 1 day.
- Scenario 3: production of hydrogen with electrolyser, storage in HDS, cooling of H2 blocks and their transport to the companies that use hydrogen for their processes; distribution to companies located at an average distance of 250 km from the production site was hypothesized (no omission). The production cycle is 2 days.
= scenario Energy supply 50% wind 50 % photovoltaic Electrolyser Hydrogen HDS Fuel cells Vehicles Industry use Electrical grid
The downstream concerns the end of life phase
- The end of life of the INGRID site by differentiating materials for each component. It was defined the recovering or the landfilling according to composition. For those activities Ecoinvent datasets was used.
Results
The main results related to the environmental impacts of the hydrogen demonstrator plant are recorded in the figures 1.
Figure 2. INGRID environmental impacts
Considering the three scenarios analysed, there is not relevant differences between number 1 (industry use) and number 3 (electrical grid). This is due to the HDS sharing which allows storing hydrogen for future possible uses (figure 1). This means a better management, in terms of quantity and timing, of hydrogen production directly related to different market demand.
Scenario number 2, indicating the production of hydrogen to supply vehicles, has the greatest environmental impact. The results show that, all the environmental impact categories are higher than the others. The main reason is due to the fact that hydrogen produced to supply vehicles is not storable. This implies its continuous production direct linked to energy input. An adequate development of hydrogen based transport system (HBTs) can mitigate these issues even if HBTs is still characterised by a demand outlook difficult to assess and to plan.
The longer term is less evident to assess, as many assumptions need to be made.
Conclusions
The LCA study results of INGRID demonstrator have highlighted the environmental impact related to the Troia demonstrator plant. The positive aspects associated with potential global environmental aspects are related to the functionality in terms of system accumulation and transformation and to the use renewable energy (photovoltaic and wind).
The results of this study, which needs further researches, could built up data helping public decision makers in deciding the right policies to support “hydrogen market”.
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