LCA for calcium magnesium acetate：LCA醋酸钙镁

LCA for calcium magnesium acetate：LCA醋酸钙镁 LCA for calcium magnesium acetate -Material Intensity and Global Warming Potential of CMA -Interim report- not for publication July 2010 Michael Ritthoff Wuppertal Institute Research group 3: Material flows and resource management Tel.: +049-202/ 2492-207 E-mail: michael.ritthoff@wupperinst.org Introduction De-icing agents are widely used under winter conditions. Most widely used is sodium- chloride (salt). Salt is a cheap and established solution for de-icing but it has a number of relevant disadvantages. It is harmful too the environment and it lead to an increased corrosion and damage of infrastructures, cars and buildings. Other established materials for winter service (grit, ashes, sand etc.) have other disadvantages. They produce fine dust and must be removed after the winter. Therefore alternatives are of growing interest. A possible alternative is calcium magnesium acetate (CMA). CMA can be used as de-icing agent in winter service and as an additional advantage, it is a binding agent for fine dust. CMA is non-toxic, not corrosive and not harmful to the environment. Against this background a ecological comparison of CMA and salt in winter service should be prepared a part of the EU-LIFE-project CMA+. Goal of this study is to compare salt and CMA in winter service with a screening LCA. Subject of the screening LCA are the resource consumption (calculated as material intensity, referring to the MIPS-concept) and the global warming potential. Other environmental impacts, damage of trees or fine dust are not covered. The calculations ha been prepared with GaBi 4 as life cycle assessment software. The calculations are based on public available information, the Wuppertal Institute database as well as on specific process Information of a producer of CMA. De-icing agents for winter service As described before, a number of different materials is used for winter service. The focus of this project is limited to sodium-chloride and calcium magnesium acetate. Sodium-chloride Sodium-chloride is used for a long time in winter service. It is used as salt, wet salt and brine. Sodium-chloride (salt, rock salt) is produced in different processes but salt for winter service is in general produced as rock salt or as a brine from salt reserves. 1Detailed life cycle inventory data are available from ecoinvent. For the calculation of material intensity these data are supplemented with data from the Wuppertal Institute MI-database to cover the material intensity adequately. The environmental indicators has been calculated for rock salt (figure 1) and brine (figure 2). 1 Hans-Jörg Althaus, Roland Hischier, Maggie Osses, Alex Primas, Stefanie Hellweg, Niels Jungbluth, Mike Chudacoff: Life Cycle Inventories of Chemicals, ecoinvent report No. 8, Dübendorf, 2004 Wuppertal Institute 2 of 8 Figure 1: Process chain for the production of salt SalzlaugeGaBi 4 Prozeßplan: MasseEs werden die Namen der Basisprozesse angezeigt. DE: Heizöl S unverbr.RER: SalzsoleX OECD: Strom DE: Erdgas unverbr. Figure 2: Process chain for the production of salt as brine All relevant inputs are covered in the calculation of salt and brine. The processes have been adjusted to European average conditions (concerning the energy mix). They do not represent a specific producer to allow a general material comparison. Table 1: Material intensity and GWP of salt and brine abiotic air water GWP material [kg/kg] [kg/kg] [kg/kg] [kg CO 2/kg] Brine (per kg salt) 1.25 0.081 8.1 0.023 Salt 1.36 0.125 17.8 0.029 Wuppertal Institute 3 of 8 Calcium Magnesium Acetate Calcium magnesium acetate (CMA) is used for dust binding and as de-icing agent. In both cases a solution of CMA is used. The production process of calcium magnesium acetate is comparable simple. CMA is produced from calcined dolomite, magnesium oxide and acetic acid. The calcined dolomite and magnesium oxide is mixed with acetic acid and reacts in a exothermic reaction to CMA. The composition of CMA can vary depending on the composition of the raw materials. The reaction follows the following reaction equation: x CaO + y MgO + 2(x+y) CHCOOH , CAMg(CHCOO) + (x+y) HO 3xy32(x+y)2 Calcium magnesium acetate is produced and used as a solution of 25% CMA. Therefore additional water is added in the reactor. 2No life cycle inventory data for CMA are published, but Nordisk Aluminat was able to provide process information that has been used for the calculation. Additionally a theoretical estimation was derived, based on stoichiometrically calculation. For the calculation of CMA, information for the production of dolomite has been taken from the Wuppertal Institute data base. These data has been additionally used as basis for the magnesium oxide (MgO) data. For the MgO the CO-emissions and the energy consumption 2 has been adjusted by stoichiometrically calculations and the difference between reaction enthalpy of calcining CaCO and MgCO. The CO-emission of MgCO is higher but the 3323 energy consumption is lower compared too CaCO. 3 The GWP of CMA can be slightly influenced by the choice of used MgO. Magnesium oxide (MgO) seldom occurs as a natural mineral but it can be produced from different sources. The most relevant source for MgO is magnesite (MgCO). Other sources are seawater and brines. 3 The GWP of the MgO produced from the different sources varies, but in all cases a CO-2 emissions from calcining of carbonates occur. If magnesite is used as raw material it must be calcined directly, if seawater or brines are used, CaO for the precipitation of Mg(OH) is 2 needed. MgO from magnesite was chosen as most representative for the production of CMA. Whatever there is only a relatively small difference in GWP between the different raw material sources. 2 Tina Klarskov Oleson: Personal communication concerning raw material and energy input for the production of CMA, May 2010 Wuppertal Institute 4 of 8 No LCA data for MgO are available. Therefore MgO was estimated with process data from the lime production and a correction of the energy consumption by taking into account the differences in heat capacity and reaction enthalpy (the production of MgO needs less energy -Emissons from the burning by as the production of CaO) and correction of the CO2 stoichiometric calculations (the CO2-emissions from MgO are higher than the CO-emissions 2 of CaO). Information for acetic acid and connected down stream processes has been taken from 3ecoinvent data base and additional information from the Wuppertal Institute MI-database to cover the material intensity adequately. The environmental indicators has been calculated for CMA from Nordisk Aluminat (figure 3) and for a theoretical composition (0.32 kg dolomite and 0.82 kg acetic acid (98%) per kg CMA) (figure 4). Figure 3: Production chain of CMA (Nordisk Aluminat) 3 Hans-Jörg Althaus, Roland Hischier, Maggie Osses, Alex Primas, Stefanie Hellweg, Niels Jungbluth, Mike Chudacoff: Life Cycle Inventories of Chemicals, ecoinvent report No. 8, Dübendorf, 2004 Wuppertal Institute 5 of 8 CMA (estimatet)GaBi 4 Prozeßplan: MasseEs werden die Namen der Basisprozesse angezeigt. DE: Heizöl el verbr.DE: Brennstoffmix DE: Heizöl S verbr. DE: Erdgas verbr. DE: Steinkohle verbr. (alt) DE: Braunkohle verbr. DE: Erdgas FeedstockRER: Methanolinkl. Emissionen DE: Erdgas 1991RER: EssigsäureCalcium MagnesiumXAcetat (estimatet) OECD: StrommixRER: Kohlenmonoxid DE: Erdöl Feedstock inkl.Emissionen Ammoniumnitrat-SprengstDolomit (Branntkalk)off (ANFO / N135) Figure 4: Production chain of CMA (theoretical composition) All relevant inputs are covered in the calculation of CMA from Nordisk Aluminat. For the theoretical composition of CMA the energy consumption of the final CMA production process is not covered. All processes has been adjusted to European average conditions (concerning the energy mix). Table 1: Material intensity and GWP of CMA abiotic air water GWP material [kg/kg] [kg/kg] [kg/kg] [kg CO 2/kg] CMA 25% (Nordisk 0.765 0.230 19.25 0.289 Aluminat) CMA 25% 0.701 0.195 15.92 0.232 (theoretical composition) There are only minor differences in all indicators between the theoretical composition and the specific CMA from Nordisk Alumiant. Therefore, the CMA from Nordisk Aluminat seems to be representative. CMA has in all indicators higher values than salt and brine. Most obvious is the difference in GWP. This difference is result of the use of carbonates that has to bee calcined in the production of CMA. The GWP can be slightly influenced by the relation between CaO and MgO but it can not be changed on a relevant level. Wuppertal Institute 6 of 8 Application of CMA and Salt The indicator values per kg do not show directly which de-icing agent has the better environmental performance under the conditions of a real application. Therefore the indicators per kg has been multiplied with the typical amount (10 g CMA/m? or 20 g salt/m?) that is used in winter service. CMA (NA) CMA (NA) Brine Salt (25% solution, (25% (20 g salt (20 g/m?) 10 g/m?) solution, /m?) 10 g/m?; once in four days) abiotic 1.9114 25.0 g/m? 7.6454 27.2 material air 0.5742 1.62 g/m? 2.2969 2.5 water 48.135 162 g/m? 192.54 356 GWP (kg 0.7217 0.46 g/m? 2.8868 0.58 CO) 2 CMA has advantages with respect to the abiotic material consumption and the water use. The air use is comparable and the GWP is for CMA much higher. The high GWP is a result of the calcining of carbonates, the influence of the fuel consumption is comparable low. In case of a preventive application of CMA (10 g/m? once in four days), CMA has advantages in the material intensity and only minor disadvantages in GWP. Preliminary conclusions and further steps The result is ambiguous. CMA in winter service has a lower material intensity but a higher GWP compared to salt. But ist has to be taken into consideration, that the use of salt in winter service is connected with massive damages at infrastructures, cars and plants. This was not included in the first part of the investigation. CMA does not lead to increased damage of steel and plants. Therefore it seems possible, that an inclusion of damages would lead to an much more clear result with clear advantages for CMA. However, this is not included in the contract but it is an option for an additional investigation. Wuppertal Institute 7 of 8 Literature Tina Klarskov Oleson: Personal communication concerning raw material and energy input for the production of CMA, May 2010 Hans-Jörg Althaus, Roland Hischier, Maggie Osses, Alex Primas, Stefanie Hellweg, Niels Jungbluth, Mike Chudacoff: Life Cycle Inventories of Chemicals, ecoinvent report No. 8, Dübendorf, 2004 Daniel Kellenberger, Hans-Jörg Althaus, Tina Künniger, Niels Jungbluth: Life Cycle Inventories of Building Products, ecoinvent report No. 7, , Dübendorf, Juli 2004 Ullman’s Encyclopedia of Industrial Chemistry, 7th ed., electronic Version 2009 Wuppertal Institute 8 of 8