ELECTROLYTIC SYSTEMS Comparison technologies

Transcription

1 ELECTROLYTIC SYSTEMS Comparison technologies Written by: Emanuele Castioni SPI Consulting S.r.l.

2 Index 1. Comparison technologies pag 3 2. Efficency pag Energy Efficency Credit pag 6 3. Opex pag 7 4. Conclusion pag 8

3 1. Comparison technologies The main technologies for generating on-site gaseous hydrogen are: Alkaline enstack by Spi Consulting These technologies are differentiated by the electrolytic substance that makes up an electrolytic stack (the device able to split water into hydrogen and oxygen through electrical energy). The Alkaline technology is generally a technology in which the electrolyte liquid solution is a basic type and whose concentration is higher than 10% by weight (generally 25-30% w). Standard alkaline electrolyte cells use catalysts to accelerate the cleavage process based on metallic nickel. The anionic exchange takes place through an inefficient porous septum which makes this technology economically from the chemical point of view, but very limited in efficiency. The technology is, usually, a technology in which the electrolyte solution is in acidic solid form. The Acid electrolyte stack use catalysts to accelerate the splitting process based on Platinum and other noble metals. The ionic exchange takes place through a polymeric membrane in which the electrolyte is inside and also has the function of separating the two gases from the production side. This technology is very expensive from a chemical point of view, but has a good efficiency. The enstack technology, developed by Spi Consulting, is a technology in which the electrolyte solution is a basic fluid type and whose concentration is 1-2% by weight. The enstack electrolyte stack typically use Platinum catalysts, to accelerate the splitting process, in much smaller amounts than s and Nickel. The ionic exchange takes place through a polymeric membrane in which there are electrolytic substances which improve the water splitting efficiency and also have the function of separating the two gases from the production side. This technology is much cheaper, from a chemical point of view, than but, at the same time, has an excellent efficiency.

4 Schematic Various Electrolytic Plant: AE Alkaline Electrolyser Solid Polimeric Electrolytic Membrane Electrolyser enstack Anionic Membrane Exchange Electrolyzer (AME) The main technical differences are shown below in the table. TECHNOLOGY FEATURES Water Type ALKALINE enstack ASTM Type II Grade High Pure ASTM Type II Grade Electrolyte > 20% - 1% Efficiency < 70% < 70% > 85% Differential pressure no yes yes Maximum Outlet Pressure 20 bar > 20 bar > 20 bar Direct Renewable Power Source no yes yes H2 Purity Outlet 95,0% 99,5% 99,5% w w Table 1

5 The different technologies compared shows substantial differences in terms of: Efficiency Opex (Operating costs) 2. Efficiency From an industrial viewpoint, efficiency have a very important role in terms of electrical consumption and average life of the equipment. Assuming an operation equal to 8000 h / year for a generator with a flow rate of 10Nm 3 / h, the electrical consumptions for the part of electrolysis are detectable from the following graph. Energy Consumption Based on 8000h/year of running STANDARD ALKALINE GENSTACK Series 343 Quindi il risparmio è: MWh/year Theroretic Energy Consumption 10Nm3/h Graph 1 Considering the share of electricity, the savings obtained using the enstack technology can be summarized in; Standard Alkaline: : -145 MWh/year equal to 35% of energy expenditure -118 MWh/year equal to 42% of energy expenditure The consequent economic savings considering the specific cost of electricity of 0.12 / kwh is: Standard Alkaline : /year /year

6 2.1. Energy Efficent Credit The current regulations reward the most efficient equipment, giving an economic value to savings in primary energy, that is in fossil fuels and therefore also in CO 2 saved. The mechanism of Energy Efficiency Credit (EECs white certificates ) constitutes an additional source of income for companies that carry out energy efficiency measures in any industrial process. The white certificates are bonds that are traded by operators certified UNI CEI through a special stock exchange and have a unit value that ranges between 280 and 360 euros. In that case, the g-enstack series produces hydrogen using less electricity compared to competitors that use other technologies, this means less consume of primary energy equivalent to one tonne of oil (tep) and consequently a lower production of CO 2 as shown in the following graph in which it is considered a hydrogen generator with a capacity of 10 Nm 3 /h running 8000 h / year. Footprint impact Based on 8000h/year of running GENSTACK Series STANDARD ALKALINE te_co2 tep Grafico 2 Taking the Alkaline Standard technology as a consumption reference (baseline) as it is considered commercially the most widespread technology in the industrial field and considering that 1 TEE = 1 tep, can be summarized Primary Energy (tep) Reduction (%) EEC* ( ) g-enstack Alcalino Standard 91 baseline - * A trading price of 280 / TEE is considered.

7 In a hypothesis in which g-enstack was connected to a renewable source that fully satisfied its needs, white certificates would be 91, since there would be no primary energy consumption, maximizing its profitability. For this reason SPI Consulting has in its staff an Energy Management Expert certified UNI CEI 11339, who is authorized to treat the EEC for its customers and thus maximize the yields of the g-enstack series machines. 3. Opex Operating costs are an important item in a company's financial statements and must be considered for the choice of industrial investments. The main operating costs for a hydrogen generator are: Electric energy Process water Ordinary maintenance The main items of expenditure for a hydrogen generator with a capacity of 10 Nm 3 / h operating 8000 h / year are shown in the following graph.

8 OPEX Analysis Based on 8000h/year of running 160,00 140,00 11,20 120,00 100,00 7,20 55,34 17,50 k /year 80,00 60,00 40,00 41,14 56,50 80,74 58,56 56,50 20,00 - GENSTACK Series STANDARD ALKALINE Water EleCricity Maintenance Grafico 3 g-enstack Standard Alcalino COST REVENUE % % % Water* % % % Electric energy % % % Maintenance % % % TOTAL % % % White Certificate % % 0 0% TOTAL % % 0 0% TOTAL SPECIFIC COST ( /Nm 3 ) 1,22 4,25 1,66 Tabel 2 summery: costs and revenues * Cost of water purchase in 1000 kg tanks: 0.83 / kg for ASTM Type II water and 1.19 / kg for ASTM Type I water used by technology.

9 4. Conclusion Making a detailed and conclusive analysis of what has been reported, it can be creeped that OPEXs change according to the technology used: an alkaline hydrogen generator needs demineralized water but the porous septum does not allow great efficiencies compared to a low initial investments; the system is composed, in addition, of a pressure compensation tank which makes the annual maintenance costs quite high. a hydrogen generator has the need to run with pure water; in addition to having high initial investment costs due to the presence of noble metals, but with high yields an g-enstack hydrogen generator combines the best of the other two technologies. It uses demineralized water for the process, allowing high efficiency with low maintenance costs and low initial investment due to the minimum presence of noble metals.