From e6f1858b35a85b943f1ca9e63ba112dec42180da Mon Sep 17 00:00:00 2001 From: Jürgen Knödlseder Date: Sat, 19 Feb 2022 00:06:07 +0100 Subject: [PATCH] Document carbon footprint evaluation --- doc/source/users/environment.rst | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ doc/source/users/index.rst | 1 + 2 files changed, 64 insertions(+), 0 deletions(-) create mode 100755 doc/source/users/environment.rst diff --git a/doc/source/users/environment.rst b/doc/source/users/environment.rst new file mode 100755 index 0000000..7c1d516 --- /dev/null +++ b/doc/source/users/environment.rst @@ -0,0 +1,63 @@ +.. _sec_environment: + +Environmental impact +==================== + +Like any human activity, using ctools will have an environmental impact. This +includes for example the greenhouse gas emissions related to electricity +production that is needed to run your computer or data centre. It includes as +well the environmental footprint of your computing hardware, the power and +material behind your internet connection, your storage array, and even the +footprint of the personnel that eventually runs your data centre. + +As ctools user you should be aware of this footprint, and you should aim +to reduce it as much as possible. + +To guide you in this endeavor, all ctools and cscripts inform you at the end +of the log file about the estimated carbon footprint of your computations: + +.. code-block:: bash + + 2022-02-18T22:33:26: Application "ctlike" terminated after 3910.0 wall clock seconds, consuming 3881.18 seconds of CPU time and generating a carbon footprint of 3.81083 g eCO2. + +This estimate is based on the study of +`Berthoud et al. (2020) `_ +who assessed the carbon footprint of the DAHU cluster of the UMS GRICAD (Grenoble, +France) in 2019. Their study included + +* server fabrication +* server environment +* server usage (electricity) +* travelling of personnel in the context of their work +* travelling of personnel from home to office +* personnel equipment +* personnel energy + +`Berthoud et al. (2020) `_ +found that, per CPU hour, the footprint of the GRICAD data centre was 2.43 g CO2e +(equivalent CO2 emissions) due to electricity use and 2.25 g CO2e due to the data +centre environment, hardware fabrication and the personnel. For their study a +carbon intensity of 108 g eCO2 / kWh for greenhouse gas emission due to +electricity generation was assumed. + +The latter varies substantially between countries. While the current electricity mix +in France has a (rounded) carbon intensity of 60 g eCO2 / kWh, values go through +240 g eCO2 / kWh (Spain), 410 g eCO2 / kWh (Italy), 460 g eCO2 / kWh (Germany), +520 g eCO2 / kWh (USA), up to 840 g eCO2 / kWh (Australia). So eventually, you should +think about doing your computations in a country with a low carbon intensity, or make +sure that your data centre is running on a low carbon energy source. + +ctools will determine in which country your code is executed and fetch the appropriate +carbon intensity for the general energy mix in this country to estimate the carbon +footprint of your computations. The estimate is done using + +.. math:: + {\rm Carbon\,\,footprint} = \left( 2.25 + 2.43 \frac{\rm CI}{108} \right) \times {\rm CPU\,\,hours} + +where :math:`{\rm CI}` is the carbon intensity of the electricity mix in your country +in units of g eCO2 / kWh, :math:`{\rm CPU\,\,hours}` is the number of CPU hours your +computation took, and :math:`{\rm Carbon\,\,footprint}` is the carbon footprint in g eCO2. + +The carbon footprint of all ctools and cscript runs are stored in an ASCII file +that you will find in a folder under your home directory, named ``.gamma/statistics.csv``. + diff --git a/doc/source/users/index.rst b/doc/source/users/index.rst index f6c01c3..a2ac868 100755 --- a/doc/source/users/index.rst +++ b/doc/source/users/index.rst @@ -14,4 +14,5 @@ This documentation will guide you in the process of using ctools. doxygen tips/index user_contributed/index + environment glossary -- libgit2 0.21.4