Introduction to the Energy performance and Carbon emissions Assessment and Monitoring Tool (ECAM-Tool)

Transcription

1 Introduction to the Energy performance and Carbon emissions Assessment and Monitoring Tool (ECAM-Tool) Beta Version WaCCliM June 2015

2 Table of Contents Preamble... 3 The Objective of the ECAM-Tool... 3 Methodology... 3 The General Approach... 3 The Scope of the ECAM-Tool... 4 The Parts of the Urban Water Cycle Included in the ECAM-Tool... 4 Overview of GHG Emissions in water and wastewater utilities... 5 Overview of GHG Emissions in Included in the ECAM-Tool... 5 The structure of the ECAM-Tool... 9 The Data Structure: Input Data, Variable and Performance Indicators Annexes Annex 1 Emissions not included in the ECAM-Tool Annex 2 List of Performance Indicators and Variables in the ECAM-Tool Figures Figure 1 Urban water cycle with the utility boundaries considered for the methodology marked in red... 4 Figure 3 - GHG emissions per scope and stage quantified in the ECAM-Tool. (Refer to Annex 1 for discussion on non-included emissions)... 6 Figure 3 Global GHG emissions quantified in the ECAM-Tool Figure 5 Structure of the ECAM-Tool Tables Table 1 Types of data/information used on the tool and correspondent definitions Introduction to the ECAM-Tool 2

3 Preamble Greenhouse gas (GHG) emissions from combustion of fossil fuels (e.g. coal, natural gas, fuel) are causing an increase in the earth s temperature. Effects of this global warming include rising sea levels and shifting rainfall patterns. As a consequence, water scarcity, flooding and erosion occur more frequently and intensively. These impacts of climate change are a threat to human life, housing, drinking water supplies, harvests and production. In order to ensure adequate water management in the future, the water sector has to adapt to climate change. The provision of drinking water and the treatment of wastewater also contribute to greenhouse gas emissions. Water and wastewater companies are typically energy intensive, as 10%-35% of their total operational costs are energy related. The Carbon footprint of water and wastewater Utilities can be reduced through energy efficiency measures, including water loss reduction, but also through reducing the direct and indirect greenhouse gas emissions from wastewater treatment plants (methane and nitrous oxide), for example by reusing treated effluent on crops. By updating technologies and management processes in water and wastewater companies into more energy-efficient systems, as well as recovering energy, nutrients and other materials from wastewater, there are excellent opportunities for improving the carbon balance of water and wastewater companies and thus contributing to climate change mitigation. Investments in energy efficiency and energy production in urban water systems can also be extremely cost effective. If well planned, these investments have pay-back times of only a few years and generate a double benefit: reducing operating costs while reducing the companies and overall country s carbon footprint. The Objective of the ECAM-Tool The ECAM-Tool, was developed under the Water and Wastewater Companies for Climate Mitigation (WaCCliM) project, which is a joint initiative between the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) and the International Water Association (IWA), acting on behalf of the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB) as part of the International Climate Initiative. In the WaCCliM project, the ECAM-Tool is intended to assist the Pilot utilities, as well as follower utilities, in using their own data to transform it into a source of valuable information 1/ on the energy performance of the utility and 2/ to understand which stages within the urban water cycle could reduce their carbon emissions. The specific utility results are also compared with known benchmarks so that inefficiencies can be highlighted, and decision makers may initiate improvements in the most promising stages within the utility. Methodology The General Approach The proposed ECAM-Tool is to be used by utilities to evaluate their operations in terms of GHG emissions and energy use. The methodology considers the global performance as well as the performance of each of the 6 stages of the urban water cycle (i.e. water abstraction, Introduction to the ECAM-Tool 3

4 water treatment, water distribution, wastewater collection, wastewater treatment, wastewater discharge). The tool also assesses the quality of service, because a reduction in GHG emissions can only be considered if it does not compromise the quality of the service provided. The service levels and energy performance are calculated based on IWA s Performance Indicators publications for water supply and wastewater and some additional indicators. The energy requirements are translated into GHG emissions using the country s electricity mix 1. The other emissions of nitrous oxide (N 2 O) and methane (CH 4 ) during operations are assessed with an adapted methodology based on the Intergovernmental Panel on Climate Change (IPCC6). The Scope of the ECAM-Tool The Parts of the Urban Water Cycle Included in the ECAM-Tool Figure 1 shows the utility boundaries considered. Figure 1 Urban water cycle with the utility boundaries considered for the methodology 1 Using the country s electricity mix was an assumption made for the WaCCliM utilities in order to avoid fluctuations of the GHG emissions that are unrelated to the performance of the utility itself. A variable electrical mix during the project would make it more difficult to assess where to improve and where progress has been made. Other utilities, not in the WaCCliM project may decide to use the exact mix of electrical power, instead of the country mix. The tool is also not designed to account for hourly variations (night / day) or daily variation (weekdays / weekends) of the electricity mix. Introduction to the ECAM-Tool 4

5 The ECAM-Tool assesses the energy performance and the GHG emissions of the following 6 stages of the urban water cycle: 1. water abstraction and transmission systems, 2. water treatment, 3. water transport and distribution, 4. wastewater collection, 5. wastewater treatment 6. wastewater interception and discharge Overview of GHG Emissions in water and wastewater utilities GHG emissions are accounted for a system with defined boundaries. The ECAM-Tool focuses on water and wastewater utilities, therefore only emissions related to the mission of the utility (delivering drinking water to - and collecting and treating the wastewater from - connected households) are considered: Three types of GHG emissions, called scopes by the IPCC, are distinguished: Scope 1 direct GHG emissions occurring within the water or wastewater utility boundary. These include the emissions from fuel combustions for on-site engines, the operation of trucks used for the network and facilities maintenance, as well as direct emissions of methane or nitrous oxide from sewers and sewage treatment. Scope 2 indirect GHG emissions associated with the consumption of grid electricity. Scope 2 emissions account for GHG emissions from the generation of the purchased energy and are hence dependent on the composition of the fuel mix of the imported energy. For example GHG emissions are generated offsite at power plants to produce the electricity that makes a water pump operate at the water treatment plant. Scope 3 all other indirect emissions, which are a consequence of the services provided, but which come from sources not owned or controlled within the water or wastewater utility, or are emitted outside of the water or wastewater utility s boundaries. The scope 3 emissions include the emissions from the use of chemicals, materials used for construction, the transport of sludge to its disposal site, and the emissions of nitrous oxide and methane from the discharge of treated or non-treated wastewater to a water body, and/or from land applied sludge. Overview of GHG Emissions in Included in the ECAM-Tool Due to limited data availability, and due to the limitations of general methodologies to assess GHG emissions, when specific data is not available, the ECAM-Tool accounts for as many emissions as possible, keeping the focus on assessing emissions on which the utilities can assess the impact of from their operational or technology measures. The methodology underlying the ECAM-Tool is designed to support utilities evaluating their performance. The main objective is to provide useful information to support diagnosis and the first step towards an improvement strategy. Therefore, the methodology focuses on the GHG emissions and energy use that is directly associated with the utility operations. This approach ensures that the methodology is useful for the utility but, for different practical reasons, it does not cover all the GHG emissions of the urban water cycle (refer to Annex 1). Introduction to the ECAM-Tool 5

6 Figure 2 shows urban water cycle GHG emissions divided by scope that are included or not this assessment methodology. Figure 2 - GHG emissions per scope and stage quantified in the ECAM-Tool. (Refer to Annex 1 for discussion on non-included emissions) The sections below detail the emissions from the 3 scopes, included in the ECAM-Tool. Scope 1 - Direct emissions The direct emissions considered in the ECAM-Tool are the consequence of the fossil fuels used (e.g. on site generators and engines) by the utilities and the CH 4 and N 2 O emitted during the wastewater treatment. - The stationary fossil fuel combustion emits carbon dioxide (CO 2 ), CH 4, and N 2 O which can be estimated based on default emission factors for the appropriate fuel consumption per IPCC guidelines. - CH 4 is directly emitted in plants with anaerobic digestion when the biogas (68% methane) is not valorized, but sent to a flare for burning. The emissions are assessed based on IPCC methodology. The emissions of methane from poorly aerated treatment are also assessed based on IPCC methodology. - N 2 O is emitted during biological wastewater treatment, specifically during nitrification and denitrification for nitrogen removal. Because N 2 O is particularly important due to its high global warming potential, the beta-version of the ECAM-Tool quantifies these emissions for information and raising awareness of its potential contribution. However, it does not include them in the total GHG emissions of the utility, because Introduction to the ECAM-Tool 6

7 the IPCC default emission factor used to quantify them is related to population and is generic for all plants; whereas, it is now generally accepted that operational conditions largely dictate N 2 O emissions and can vary widely from facility to facility, and seasonally. Scope 2 - Indirect Emissions from Electricity The production of electric energy emits GHGs, whenever the process involves the use of non-renewable sources of energy. Efficient operations in the utility use less electric energy, thus emitting less GHGs. The GHG emissions from real consumed energy (electric) are calculated taking into account the fuel mix of the electricity imported by the utility. If the utility is producing renewable electricity (i.e.: solar panels, hydro-turbines or biogas cogenerators), the energy produced is deducted from the total electrical energy use prior to converting the electricity demand into GHG emissions (refer to Figure 3). Note that the electricity produced is most of the time sold to the grid rather than self-consumed to avoid having to deal with difference between supply and demand. Scope 3 Other Indirect Emissions Other indirect emissions are a consequence of the services provided, which come from sources not owned or controlled within the water or wastewater system, or are emitted outside of the utility boundary. The scope 3 emissions included in the ECAM-Tool are the emissions from the transport of sludge to its disposal site, and the emissions of nitrous oxide and methane from the discharge of treated or non-treated wastewater to a water body: - Emissions related to the sludge transport from the wastewater treatment to final destination (e.g. landfill). These emissions are related to the vehicle fuel consumption during disposal. They are directly related to the performance/operations on-site because the level of sludge dewatering before disposal dictates the amount of trips needed. These emissions are calculated based on the amount and type of fuel consumed, multiplied by emission factors per IPCC guidelines. - Emissions related to the discharge to a water body: o N 2 O emitted from treated effluent after discharge. N 2 O emissions are estimated based on the nitrogen discharged by the effluent to the waterbody, multiplied by a default emission factor per IPCC guidelines. These emissions relate to the nitrogen removal performance of the wastewater treatment plan. o N 2 O emitted from raw wastewater discharged to a water body. These emissions are directly related to nitrogen concentration of the raw wastewater. N 2 O emissions are estimated based on the nitrogen concentration of the untreated wastewater if known, multiplied by a default emission factor per IPCC guidelines. When the concentration is not known, the emissions are estimated using the IPCC method based on a per capita protein consumption (country dependent). o CH4 emitted from raw wastewater discharged to a water body. These emissions are directly related to the BOD load of the raw wastewater, and if known, are multiplied by a default emission factor per IPCC guidelines. When the concentration is not known, the emissions are estimated using the IPCC method based on a per capita BOD input to sewage (continent dependent). Introduction to the ECAM-Tool 7

8 Two systems boundaries are used for two different indicators: - Indicator Total emissions per serviced population (kg CO2e/serv. Pop.), which is intended to link the emissions to the population receiving the service 2. In this case the emissions from raw wastewater discharge are not considered. This indicator is intended to drive short-term improvements, and is used for the reporting of the WaCCliM project. - Indicator Total emissions per resident population 3 (kg CO2e/serv. Pop.), which is intended to link the emissions to the service area of the utility. In this case the emissions from raw wastewater discharge are included. This indicator is intended to drive long-term improvements, including the increase of sewage treatment coverage. Figure 3 summarizes the approach for computing the global GHG emissions Translated into indicators Emissions from services associated to providing drinking water and to collecting and treating wastewater. CO2e kg/ serv. Pop. Emissions from the utility s services area. This includes emissions associated to collecting and treating wastewater, as well as from untreated collected sewage 4 discharged directly to a waterbody. 4 CO2e kg/ inhab. 2 Serviced population is defined for the wastewater system as the population which is connected to the sewer system and which wastewater is treated before discharge. 3 Resident population is defined for the wastewater system as the resident population within the service area of the utility, whether they are connected to the sewer of not. 4 Sewage that is not collected is not included, as it is not included in the boundary of the Utility and it is unknown whether this sewage is treated on-site or discharged untreated to a water body. Introduction to the ECAM-Tool 8

9 Figure 3 Global GHG emissions quantified in the ECAM-Tool. The structure of the ECAM-Tool The ECAM-Tool is structured along the GHG emissions scopes1, 2 and 3. Within Scope 2 (indirect emissions from electricity consumption), the energy consumption is evaluated to compute GHG emissions at the level of the entire water supply services and entire wastewater services. Still within Scope 2, the energy performance is assessed for the 6 stages of the urban water cycle. Within each stage, sub-stages of the system (i.e.: individual pumping station or treatment plants) are each assessed for their individual performance. The assessment of each sub-stage may not be necessary if the overall energy consumption of the stage is low, or already performing very well compared to benchmark indicators. Figure 4 shows how the different parts of the ECAM-Tool are structured to assess energy performance and GHG emissions. Each labeled solid color rectangle corresponds to one of the Excel-worksheets of the tool. Figure 4 Structure of the ECAM-Tool. Notes: - The numbers correspond to the worksheet as numbered in the ECAM-Tool - The color codes shown on this figure are the color codes used throughout the graphical presentation of results for the different stages and types of emissions (scope 1, 2 and 3) - The scope 2 emissions are assessed only for the entire water supply services and for the entire wastewater services. The stages (worksheets 5 through 10) are only used for energy performance assessment, but not for GHG emissions. Introduction to the ECAM-Tool 9

10 The Data Structure: Input Data, Variable and Performance Indicators Most data is generated at the utility level (e.g. flow rates) but occasionally, data is retrieved from a third party (e.g. electric energy mix). The data collected (input data) is transformed into information in the form of variables and indicators as shown in Table 1. Table 1 Types of data/information used on the tool and correspondent definitions Data/Information Input Data Variables Indicators Definition The data available to the utility. This input data can be static such as the characteristics of a stage or sub-stage (e.g. Treatment technologies used on wastewater treatment) or dynamic such as values that change on a daily basis (e.g. Volume of water pumped on water distribution). The input data is the starting point to use the tool. Variables are the building blocks of the tool. They are either directly available to the utility (as input data) or they are calculated based on the input data available. The variables are grouped in three different types, corresponding to the three different types of PIs that they contribute to: context variables; key variables and complementary variables. Indicators are the outputs of the tool, they are the result of the transformation of raw meaningless data into valuable information. Indicators are calculated based on the variables. The indicators are grouped in three different types: 1. Service Level or Context Indicators, which provide information that is useful to characterize the system, they do not evaluate directly the energy efficiency and GHG emissions but they help explaining the value of the performance indicator; 2. Key Performance Indicators, which are the indicators that directly evaluate the objectives of the tool in terms of GHG emissions and energy efficiency; 3. Complementary PI are indicators that provide an insight into the processes taking place on each stage of the system and are also useful information for the utility. They allow for a more in depth energy performance assessment, to understand where inefficiencies might come from. Instructions on how to enter data and how to use the tool are shown on the first page of the Tool. In addition, under each tab, the Variables and PI calculated are described when clicking on the? symbol. The list of PIs and Variables is presented in Annex 2. Introduction to the ECAM-Tool 10

11 Annex 1 Emissions not included in the ECAM-Tool Type of emission Emissions from end users CH 4 emissions from sewers N 2 O emissions from sewers CO 2 emissions from biological wastewater treatment N 2 O emissions from treatment Rationale The use of non-renewable energy by end users to heat water is a major source of GHG emissions in the water cycle. End users also have an impact on the overall energy use in the Urban Water Cycle through w overconsumption of water, as well as the type of waste (micro-pollutants) they are discharging (which then impact the wastewater treatment required).these emissions were not included in the assessment methodology because these emissions are not the direct responsibility of the utility. Secondly, data about end user use of energy and water is dificult to obtain. Nevertheless, from a broader perspective, taking into account these emissions is a key steps towards urban water cycle energy neutrality. Methane is a potent greenhouse gas with a global warming potential of 34 CO2- equivalents over a 100 year time horizon as reported by IPCC (2013). Methane can be produced in sewers via conversion of organic carbon by methanogenic archea under anaerobic conditions, and then released into the atmosphere via manholes and atmospheric discharge points. Although methane emissions have been measured in both gravity (de Graaff et al., 2012), and pressure sewers (Guisasola et al., 2008), the risk of production tends to be greater in pressure sewers since there is generally no air/water interface to diffuse oxygen into the liquid phase and promote aerobic conditions. Methane production is also directly related to the detention time of the wastewater in sewer anaerobic conditions. Although IPCC (2006) indicates that closed underground sewers, which are predominant in the UWS, do not contribute significant CH4 emissions, studies have shown the contrary. One study (Guisasola et al., 2008) found sewage methane to contribute GHG emissions between % of those from a WWTP itself. However, there are not yet any conventional methods for estimating these emissions that can easily be implemented by a water utility. Therefore, they are not included in the baseline GHG estimation framework proposed herein. Nitrous oxide is another potent greenhouse gas with a global warming potential of 298 CO2-equivalents over a 100 year time horizon (IPCC, 2013). Although some studies have reported N2O emissions to be significant from sewers (Short et al., 2014), the conditions leading to N2O emissions in sewers are still not well understood. IPCC also does not consider sewers as a source of N2O emissions; hence, they will not be considered as such in the proposed GHG assessment framework strictly for consistency. These can be emitted directly from the activated sludge process as a byproduct of microbial breakdown of organic matter in aeration tanks. IPCC considers this source to be biogenic in nature, hence not a contributor to increased CO2 concentrations in the atmosphere. Biogenic carbon is the carbon which is emitted during the carbon natural cycle, a direct consequence of decomposing organic matter and not burning fossil fuel. Therefore, this source will not be included in the project for consistency with IPCC guidance. Although nitrous oxide (N2O) emissions are known to occur in biological wastewater treatment and can comprise a significant portion of the WWTP GHG emissions, it is not included in the ECAM-Tool, for three reasons: The default emission factor provided in the IPCC guidelines is based upon one study in the U.S. and may not be representative for other WWTPs. The default emission factor provided in the IPCC guidelines is based upon population; therefore, it does not capture the effects of improved operations and GHG reduction measures when applied. However, the potential for N2O emissions can be assessed qualitatively and can be monitored and considered along with other GHG reduction measures to verify mitigation of N2O risk, or at least that risk is not increasing significantly as a result of proposed measures. International research is working on the definition of an improved N2O emission factor for WWTP and a future version of the ECAM-Tool will likely include it. It is Introduction to the ECAM-Tool 11

12 important not to ignore these emissions as they are 298 times more potent than CO2 emissions in terms of global warming potential. In order to raise awarness on the importance of these emissions, their CO2 equivalent is calulated in the tool, using the generic IPCC emission factor for WWTP N2O emissions of EFPLANT = 3.2 g N2O / person / year, but the calculated quantity is not added to the total emissions, as it may not be representative given the wide variability observed in various measurement campaigns around the world. Introduction to the ECAM-Tool 12

13 Annex 2 List of Performance Indicators and Variables in the ECAM-Tool Introduction to the ECAM-Tool 13