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Impact Information
This page contains information about the impact files used within CLOVER for analysing systems or appraising them as part of CLOVER's optimisation process.
CLOVER is able to consider two main sources of impact: environmental and economic. These data are contained within the greenhouse gas (GHG) and finance impact files. We'll take a look at each of these in turn.
Financial information is often the key decision metric for designing and implementing a system: renewable energy systems can provide a number of co-benefits, but often ultimately need to make financial sense in order to be selected for deployment. This could be in terms of providing electricity at a given price, for example lower than the incumbent or some alternative option, or ensuring that the total cost of a system does not exceed a certain budget.
The inputs for the financial impact of the system are primarily included in the finance_inputs.yaml file, which is located in the impact directory of your location's inputs folder. Let’s take a look at the inputs for the Bahraich case study:
---
################################################################################
# finance_inputs.yaml - Finance input information. #
# #
# Author: Phil Sandwell, Ben Winchester #
# Copyright: Phil Sandwell & Ben Winchester, 2021 #
# Date created: 14/07/2021 #
# License: Open source #
################################################################################
# NOTE: Missing finance input data values default to 0.
#
discount_rate: 0.1 # Fraction between 0 and 1.
general_o&m: 500 # [$ p.a.]
misc:
cost: 0 # [$/kW]
bos:
cost: 200 # [$/kW]
cost_decrease: 2 # [% p.a.]
diesel_fuel:
cost: 0.9 # [$/litre]
cost_decrease: -1 # [% p.a.]
grid:
cost: 0.01 # [$/kWh]
extension cost: 5000 # [$/km]
infrastructure_cost: 2000 # [$]
households:
connection_cost: 100 # [$/household]
inverter:
cost: 200 # [$/kW]
cost_decrease: 2 # [% p.a.]
lifetime: 4 # [years]
size_increment: 1 # [kW]
kerosene:
cost: 0.008 # [$/hour]These variables describe the costs of the various elements of the energy system and will be dependent on the specifics of your location; although this is true for all of the input files, the costs are likely to vary significantly between locations and can also have a relatively large impact on the results of your optimisation. These data can be difficult to assign specific values (for example if different suppliers have different costs for a given component, or if lower costs are available for purchasing larger quantities) so the general ethos should be to use a value reflective of what is available for your location. Take care to notice the units of each variable as using an input in the wrong units would affect the costs significantly.
Not all of the financial information is contained here: quite a bit is stored on each component in the various other input files that we've encountered as we've explored our locations. We'll start by taking a look at what is here:
| Variable | Explanation |
|---|---|
discount_rate |
The discount rate or cost of finance, expressed as a fraction between 0 and 1 |
general_o&m |
General miscellaneous annual costs for the system in $ per year |
misc: capacity_cost |
General miscellaneous capacity costs for the system in $/kWp |
misc: fixed_cost |
General miscellaneous fixed costs for the system in $ |
bos: cost |
Cost of balance of systems (BOS) components for PV in $/kWp |
bos: cost_decrease |
The annual cost decrease of BOS components in % per year |
diesel_fuel: cost |
Cost of diesel fuel in $/litre |
diesel_fuel: cost_decrease |
The annual cost decrease of diesel fuel in % per year |
grid: cost |
The cost of grid electricity in $/kWh |
grid: extension_cost |
The cost of extending the grid by 1 km in $. NOTE: this parameter is currently not utilised within CLOVER. |
grid: infrastructure_cost |
The cost of transformers (etc.) to connect the system to the grid in $ |
households: connection_cost |
The cost of connecting a household to the system in $ per household |
inverter: cost |
Cost of an inverter in $/kW |
inverter: cost_decrease |
The annual cost decrease of an inverter in % |
inverter: lifetime |
The lifetime of an inverter in years |
inverter: size_increment |
The variety of available sizes of inverters in kW |
kerosene: cost |
The cost of using a kerosene lamp for one hour in $ |
The first variable, discount_rate, describes the cost of financing used when considering the value of money over time. This is input here as a fraction, 0.1, corresponding to a discount rate of 10%. The cost of financing can vary significantly between countries and projects depending on many factors, such as the risk associated with the project, and can affect the cost effectiveness of different technologies: broadly speaking, a high discount rate will discourage large initial investment (for example in solar and storage capacity) and favour repeated expenditure over time (for example on diesel fuel).
The component costs for the solar system and diesel generators are treated separately in their respective input files. However, the diesel generator has additional variables associated with the cost of fuel, whilst the solar generation system has those for balance of system components such as frames and wiring, and both have costs of initially installing the generation capacity; these are all treated in a similar way.
Two variables relate directly to households in the system. The first is connection_cost, which represents the cost of connecting a household to the system; this could include wiring, electricity meters, installation costs, or any others related to providing a household with a connection. The second is the cost associated with the kerosene system, which is the cost that a household incurs for using one kerosene lamp for one hour. This would mainly be comprised of the cost of kerosene fuel, but could also include a contribution to the cost of the lamp itself although this will likely be negligible. This variable is used to calculate the spending on kerosene by the community when electricity is unavailable.
The cost of electricity from the grid used by the system is assigned in cost under the grid entry. Additional costs associated with the national grid are the extension_cost, which represents the cost of extending the network to the community being investigated if it is not currently present there, and the infrastructure_cost, which is the cost of the transformers and other equipment used to convert power from the grid for use in the local distribution network. At present extension_cost is not used in the financial calculations, but could be used in the future to calculate the break-even distance at which an off-grid system is more cost effective than extending the national network.
Variables about the inverter used in the system are also included here, with the cost and cost decrease acting similarly to those for generation and storage capacities. In addition the lifetime of the inverter, in years, is included to govern the points in the simulation at which the inverter must be replaced and a new one is purchased; this is included here as depending on the length of a simulation period and its point in the overall lifetime of the system it may necessitate several, or no, replacements. The Inverter size_increment` variable describes the capacity of inverters that are available to be used: for example if this variable is set to 3 kW then the system can used
an inverter with a 3 kW, 6 kW, or 9 kW (and so on) capacity, with the inverter being oversized as necessary.
Finally, Misc. costs, under cost under misc, and general_o&m, can be used to include any additional miscellaneous costs that are not captured in the other variables and that are dependent on either the capacity of the system or are annually recurring, respectively.
If you are not using certain technologies in your investigation then it is not necessary to provide values for all of the variables included here. For example, if you are evaluating a solar and battery storage system operating far from the national grid network, you do not need to input values relating to diesel generators, fuel, or the cost of electricity from the national grid. In this case it is best to leave the default values in place, rather than delete them, to ensure that you do not introduce any issues in the way that CLOVER reads the CSV file. Further, setting a variable, such as the diesel fuel cost to zero, can result in issues if you inadvertently include diesel generators where CLOVER will account for demand using backup diesel generation but incur no costs for this.
Complete the finance_inputs.yaml file with the financial information for your investigation.
Across CLOVER, there are various file which contain information about the components that can be used as part of the energy systems that CLOVER considers. Each of these components contains its own financial impact information along with environmental impact information. Se ethe below section, Impacts across CLOVER, for information on how to fill in these files.
CLOVER allows users to analyse the environmental impact of their systems to explore the potential benefits of low-carbon energy technologies. At present these are considered using the greenhouse gas (GHG) emissions of the various technologies both in terms of embedded GHGs from their manufacture and the impact over their lifetimes, for example through the carbon intensity of the electricity they provide. These can be compared to alternatives, such as the carbon intensity of the national grid network, to advocate for cleaner sources of power.
The inputs for the environmental impact of the system are included in the ghg_inputs.yaml file, which is located in the impact directory within the inputs folder of your location. Let’s take a look at the inputs for the Bahraich case study:
---
################################################################################
# ghg_inputs.yaml - GHG input information. #
# #
# Author: Phil Sandwell, Ben Winchester #
# Copyright: Phil Sandwell & Ben Winchester, 2021 #
# Date created: 14/07/2021 #
# License: Open source #
################################################################################
# NOTE: Missing GHG input data values default to 0.
#
general:
o&m: 200 # [kgCO2 p.a.]
misc:
ghgs: 0 # [kgCO2/kW]
bos:
ghgs: 200 # [kgCO2/kW]
ghg_decrease: 2 # [% p.a.]
diesel_fuel:
ghgs: 2 # [kgCO2/litre]
o&m: 10 # [kgCO2/kW p.a.]
grid:
extension_ghgs: 290000 # [kgCO2/km]
infrastructure_GHGs: 1200000 # [kgCO2]
initial_ghgs: 0.8 # [kgCO2/kWh]
final_ghgs: 0.4 # [kgCO2/kWh]
households:
connection_ghgs: 10 # [kgCO2/household]
inverter:
ghgs: 75 # [kgCO2/kW]
ghg_decrease: 2 # [2,% p.a.]
lifetime: 4 # [years]
size_increment: 1 # [kW]
kerosene:
ghgs: 0.055 # [kgCO2/hour]At first glance, our file looks to be laid out in a very similar way to the Finance inputs file. This is because the impact treatment within CLOVER is almost identical for both costs and emissions information.
Similarly to the financial inputs, the environmental inputs consider the initial impact of installing the technologies (the embedded GHG emissions from their manufacture) and the impact of maintaining them, as well as the potential for technologies to decrease their impact over time as manufacturing becomes more efficient, for example. These data are typically much more difficult to identify values for as the environmental impact is rarely considered in such detail, if at all, as a secondary metric to the financial impact. As a result it may be better to either use the default values provided or set them to zero to disregard them depending on the nature of your investigation; either may be appropriate, as long as the decision is acknowledged and justified where necessary.
Again, not all of the emissions information is contained within this one file; some is distributed across CLOVER. See the Impacts across CLOVER section for more information. We'll take a look now at the variables which are contained within this file:
| Variable | Explanation |
|---|---|
general: o&m |
General miscellaneous annual GHGs for the system in kgCO2 per year |
misc: ghgs |
General miscellaneous capacity-dependent GHGs for the system in kgCO2/kW |
bos: ghgs |
GHGs of balance of systems (BOS) components for PV in kgCO2/kWp |
bos: ghgs_decrease |
The annual GHG decrease of BOS components in % per year |
diesel_fuel: ghgs |
GHGs of diesel fuel in kgCO2/litre |
diesel_fuel: ghgs_decrease |
The annual GHGs of maintaining the diesel generator in kgCO2/kWh |
grid: extension_ghgs |
The GHGs of extending the grid by 1 km in kgCO2. NOTE: this parameter is currently not used within CLOVER but is included for completeness. |
grid: infrastructure_ghgs |
The GHGs of transformers (etc.) to connect |
| the system to the grid in kgCO2 | |
grid: initial_ghgs |
The GHGs of grid electricity at the start of the time period in kgCO2/kWh |
grid: final_ghgs |
The GHGs of grid electricity at the end of the time period in kgCO2/kWh |
households: connection_ghgs |
The GHGs of connecting a household to the system in kgCO2 |
inverter: ghgs |
GHGs of an inverter in kgCO2/kW |
inverter: ghgs_decrease |
The annual GHG decrease of an inverter in % per year |
inverter: lifetime |
The lifetime of an inverter in years |
inverter: size_increment |
The variety of available sizes of inverters in kW |
kerosene: cost |
The GHGs of using a kerosene lamp for one hour in kgCO2 |
Almost all of the variables in the above table are environmental analogues to those in the financial inputs and therefore their descriptions will not be repeated here. The exceptions to this are grid: initial_ghgs and grid: final_ghgs, which describe the emissions intensity of the grid network at the start and end of the considered lifetime of the system respectively. These allow the user to take into account how the electricity grid might be decarbonised over time in line with national policy objectives, which would have a subsequent impact on the GHGs of a system using grid electricity throughout its lifetime.
In general many of the technologies have relatively carbon-intensive manufacturing processes, such as processing silicon for solar panels and smelting metals for balance of systems components and wiring, whilst diesel fuel has notoriously high emissions from its usage. Emissions associated with operation and maintenance could come from the maintenance itself (for example replacement parts) or other considerations, such as the GHGs of a worker travelling to the site; in practice, however, these O&M emissions are usually dwarfed by the embedded emissions of equipment and those from diesel fuel and the national grid. Emissions from transporting equipment are not explicitly included but can be implicitly included by adding them to the appropriate variables, for example setting PV GHGs to a value including both the emissions from manufacturing a panel and from shipping it to the installation site (both in terms of capacity, here kgCO2/kWp).
Complete the GHG inputs CSV file with the financial information for your investigation.
The various files throughout CLOVER that specify components for the system have their own associated costs and emissions information. These need to be filled out in each of the relevant files for each of the relevant components.
The general format for this information is fairly straightforward in YAML syntax:
costs:
cost: 200 # [$/unit]
installation_cost: 50 # [$/unit]
installation_cost_decrease: 0 # [% p.a.]
o&m: 20 # [$/unit p.a.]
cost_decrease: 0 # [% p.a.]
emissions:
ghgs: 2000 # [kgCO2/unit]
ghg_decrease: 0 # [% p.a.]
installation_ghgs: 50 # [kgCO2/unit]
installation_ghg_decrease: 0 # [% p.a.]The variables are similar across all components, so we'll examine the general case here:
| Variable | Explanation |
|---|---|
cost |
The cost of the component in USD. This is |
cost_decrease |
The percentage decrease in the cost of the component per year. |
installation_cost |
The cost of installing the component in USD. |
installation_cost_decrease |
The percentage decrease in the installation cost of the component per year. |
o&m |
The operation and maintenance costs of the component in USD per unit per year. |
ghgs |
The ghgs embedded in the manufacture of the component. If you do not have a specific number for the installation_ghgs`, you can combine both of these values here. |
ghg_decrease |
The percentage decrease in the associated GHGs of the component per year. |
installation_ghgs |
The GHGs associated with the installation of the component. |
installation_ghg_decrease |
The percentage decrease in the associated GHGs for installing the component per year. |
Now that we have examined the general format for this information, we need to see where we should be writing this information throughout our location. This information is contained with the following files:
| File | Contained Impacts |
|---|---|
generation/diesel_inputs.yaml |
Diesel generators, diesel water heaters; |
generation/solar_generation_inputs.yaml |
Solar panels: PV, PV-T and solar-thermal; |
simulation/battery_inputs.yaml |
Batteries. |
Fill out the impact information for each of the components you are considering across these various input files.