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A5 Results
Summary of work completed so far under A5:
• Flow charts of the two main technologies – AwR and BABIU
• Literature review
• Life cycle inventory
o Emails sent to all manufacturers, only 2 responses were received. Questionnaires sent to 2 high pressure water scrubbing manufacturers
o Information request sheets sent and filled out by partners in the project
o Literature review in order to compile basic information on 5 other biogas upgrading technologies
• Life Cycle Assessment
o Various studies conducted using different system boundaries as well as different functional units
o The other upgrading technologies that alkaline with regeneration (AwR) and bottom ash for biogas upgrading (BABIU) were compared to include: High pressure water scrubbing (HPWS), Pressure swing adsorption (PSA), Chemical scrubbing with amine (AS), membrane separation (MS), cryogenic separation (Cry), and Organic physical scrubbing (OPS).
o The CML 2001 nov’09 eco-indicators were used and include: abiotic depletion, elements (ADP E) [kg Sb-Equiv.]; abiotic depletion, fossil (ADP F) [MJ]; acidification potential (AP) [kg SO2-Equiv.], eutrophication potential (EP) [kg Phosphate-Equiv.]; freshwater aquatic ecotoxicity potential (FAETP) [kg DCB-Equiv.]; human toxicity potential (HTP) [kg DCB-Equiv.]; marine aquatic ecotoxicity potential (MAETP) [kg DCB-Equiv.]; ozone layer depletion potential, steady state (ODP) [kg R11-Equiv.]; terrestric ecotoxicity potential (TETP) [kg DCB-Equiv.]; global warming potential, 100 years (GWP) [kg CO2-Equiv.]; photochemical ozone creation potential (POCP) [kg Ethene-Equiv.]. The primary energy demand from renewable and non-renewable resources, regarded as cumulative energy demand (CED)
o Functional Unit: 1 ton of CO2 removed
- LCA on HPWS, AwR and BABIU. Took into consideration transport of reagents and infrastructure.
- BABIU showed the best results while AwR the worst. The production of KOH was the main reason for all of the impacts of AwR, while BABIU’s main impact was distributed amongst transport and electricity.
Figure 1 - Disaggregated impacts of AwR
Figure 2 - Disaggregated impacts of BABIU
- For the global warming potential, as AwR and BABIU store CO2 they had the lowest impacts.
- LCA on 8 technologies
• BABIU was still found to be the best, while AwR was found to have the highest impact in most categories.
• For the global warming potential, as AwR and BABIU store CO2 they had the lowest impacts.
o Functional Unit: 1 kWh of biomethane produced
- Global warming potential study on all 8 technologies. The amount of methane that is isolated and therefore prevented from being released into the atmosphere is regarded as a CO2 savings.
• BABIU had the highest savings, while AwR had the second highest savings.
| Technology | Spain | Italy |
| BABIU | 1977 g | 1975 g |
| AwR | 1794 g | 1793 g |
Table 1. Potential CO2 savings per 1 kWh of biomethane per country
• The KOH still was the main source of CO2 emissions. If the KOH is replaced by NaOH its emissions are reduced. As well if the regeneration rate of this reagent is increased from 70% its emissions are reduced, though it cannot reach the same CO2 savings as achieved through the BAIBU process.
• Transport distances between municipal solid waste incinerators (MSWI) and the upgrading plant are important. For this functional unit, at a distance of 145 km the impact of BABIU and AwR have the same impact, and after that the impact of BAIBU is higher than that of AwR, as it requires a large amount of bottom ash to be transported. When the distance between the MSWI and a BABIU plant reaches around 1315 km the impact from transport becomes higher than any CO2 savings and the process begins to have a negative impact on the environment. For AwR, this point is reach at a much further distance of around 10475 km.
- LCA on 8 technologies across 12 indicators
Figure 3 - Comparison of impacts of upgrading technologies for 1 kWh of biomethane produced
• Compared across all 12 CML 2001impact categories, BABIU has the best performance in 8 categories and the second best in 3. Only in ozone layer depletion (ODP) potential does BABIU have the second highest impact, behind AwR.
• AwR had the highest impact in 11 categories. In global warming potential (GWP) it has the second lowest impact after BABIU. The KOH that is needed for this process is the main cause of the high impact across all categories.
General conclusions based on LCA:
BABIU has the best savings. AwR needs to improve the regeneration rate of KOH and/or replace it with another base.
The upgrading plant should be located near a MSWI plant or else any benefits obtained may be negated if the transport distance is too great.
Material Flow Analysis
o Scenarios were planted to examine the potential flows within Spain in 2008 if either BABIU or AwR is used to upgrade all biogas from landfills and anaerobic digestors
1 – waste flows are the same as the current situation
2 – all Organic matter is selectively collected and sent to aneorbic digestion, all other unsorted waste is sent to MSWI
3 – All unsorted waste is sent to the MSWI
o If AwR and/or BABIU were applied to all landfills a lot of biomethane would be produced but there would not be enough Bottom ash or air pollution control residues generated from MSWI to run these technologies.
o From the scenarios it is clear that under current situations not enough Bottom ash can be produced to meet the needs of BABIU if it is applied to the whole country, therefore it should be applied on a case by case basis.
o Potentially enough APC can be produced to meet the needs of AwR installed on all anaerobic digestors.
o If all unsorted waste is sent to MSWI then potentially enough BA could be produced to fulfill the needs of BABIU when applied to anaerobic digestor.
o The collection of data for the municipal waste treatment flow of Spain and Austria has been completed while the analysis for Italy is underway.
o For comparison, the natural gas flow data is also being collected and further analysis will be completed.
Figure 4 - Municipal Waste flows of Spain in 2008
Figure 5 - Municipal waste flows of Austria in 2008
Exergy Analysis
o Preliminary exergy efficiency was conducted on AwR, BABIU and HPWS:
HPWS 93%, BABIU 85%, AwR 80%
o This data is preliminary as the data is not complete. Once it is obtained further analysis will be conducted including a cumulative exergy study
Innovative processes for biogas upgrading - Presentation of results of the Project UPGAS-LOWCO2
Innovative processes for biogas upgrading - Presentation of results of the Project UPGAS-LOWCO2
