dynamic_characterization

This is a package for the dynamic characterization of Life Cycle Inventories with temporal information. It includes a collection of dynamic characterization functions for various environmental flows. We also provide a simple interface to apply these functions to an existing dynamic LCI (coming from, e.g., bw_temporalis or bw_timex).

The following dynamic characterization functions are currently included:

module	impact category	metric	covered emissions	source
ipcc_ar6	climate change	radiative forcing	247 GHGs	radiative efficiencies & lifetimes from IPCC AR6 Ch.7
original_temporalis_functions	climate change	radiative forcing	CO2, CH4	bw_temporalis

What do dynamic characterization functions do?

The functions are meant to work with a common input format of the dynamic inventory, collected in a pandas DataFrame that looks like this:

date	amount	flow	activity
101	33	1	2
312	21	4	2

Each function takes one row of this dynamic inventory dataframe (i.e. one emission at one point in time) and transform it according to some metric. The output generated by applying a very simple function to both rows of the input dataframe could look like:

date	amount	flow	activity
101	33	1	2
102	31	1	2
103	31	1	2
312	21	4	2
313	20	4	2
314	19	4	2

How do I use this package?

The workflow could look like this:

import pandas as pd
from dynamic_characterization import characterize
from dynamic_characterization.ipcc_ar6 import characterize_co2, characterize_ch4

# defining a dummy dynamic inventory that you somehow got
dynamic_inventory_df = pd.DataFrame(
        data={
            "date": pd.Series(
                data=[
                    "15-12-2020",
                    "20-12-2020",
                    "25-05-2022",
                ],
                dtype="datetime64[s]",
            ),
            "amount": pd.Series(data=[10.0, 20.0, 50.0], dtype="float64"),
            "flow": pd.Series(data=[1, 1, 3], dtype="int"),
            "activity": pd.Series(data=[2, 2, 4], dtype="int"),
        }
    )

df_characterized = characterize(
        dynamic_inventory_df,
        metric="radiative_forcing", # could also be GWP
        characterization_function_dict={
            1: characterize_co2,
            3: characterize_ch4,
        },
        time_horizon=2,
    )

If you use this package with Brightway, stuff can get even easier: if you have an impact assessment method at hand, you can pass it to the characterize function via the base_lcia_method attribute and we'll try to automatically match the flows that are characterized in that method to the flows we have characterization functions for. This matching is based on the names or the CAS numbers, depending on the flow. The function call could look like this then:

method = ('EF v3.1', 'climate change', 'global warming potential (GWP100)')

df_characterized = characterize(
        dynamic_inventory_df,
        metric="radiative_forcing", # could also be GWP
        base_lcia_method=method,
        time_horizon=2,

)

What do dynamic characterization functions look like?

Here's an example of what such a function could look like:

def example_characterization_function(series: namedtuple, period: int = 2) -> namedtuple:
    date_beginning: np.datetime64 = series.date.to_numpy()
    dates_characterized: np.ndarray = date_beginning + np.arange(
        start=0, stop=period, dtype="timedelta64[D]"
    ).astype("timedelta64[s]")

    amount_beginning: float = series.amount

    # in reality, this would probably something more complex like an exponential decay function
    amount_characterized: np.ndarray = amount_beginning - np.arange(
        start=0, stop=period, dtype="int"
    )

    return namedtuple("CharacterizedRow", ["date", "amount", "flow", "activity"])(
        date=np.array(dates_characterized, dtype="datetime64[s]"),
        amount=amount_characterized,
        flow=series.flow,
        activity=series.activity,
    )

Installation

You can install dynamic_characterization via [pip] from [PyPI]:

$ pip install dynamic_characterization

Alternatively, you can also use conda:

$ conda install -c diepers dynamic_characterization

Contributing

Contributions are very welcome. To learn more, see the Contributor Guide.

License

Distributed under the terms of the BSD 3 Clause license, dynamic_characterization is free and open source software.

Issues

If you encounter any problems, please file an issue along with a detailed description.

Support

If you have any questions or need help, do not hesitate to contact Timo Diepers (timo.diepers@ltt.rwth-aachen.de)