Calculation details
The calculator is based on the report Monitoring the carbon footprint, which is one of the deliverables of the Remote-NMR project (Horizon Europe grant 101058595). You find the calculator here.

Power console and magnet consumption

The power consumption of the consoles are estimated from the nominal power consumption values given in the site planning manuals. For a 2K (pumped) magnet, the pumping system is expected to consume 500 W.
Console type Power (kW)

He liquefaction

The power consumption for liquefying helium at a helium production site (a side product in the liquid natural gas production) is given in Zaitsev et al. Int. J. Energy Res. 44 (2020) 6430. In this paper, Figure 11 reports the power consumption per kmole of He. The average of existing sites is ca. 235 kWh/kmole. The density of He is 125 g/L (hence the concentration is 31.25 mol/L), so the power consumption is 7.43 kWh/L (The R-NMR report says the number is 6.25 kWh/L). Jones estimate a transport contribution (to Europe) of 88 gCO2/L He corresponding to 0.38 kWh/L He. Since the helium liquefaction plants are located in both Qatar, Algeria, and USA, we separate the remote production depending on the origin. Local liquefaction of is estimated in Jones et al. Low Temp. Phys. 49 (2023) 967-970 for a local turbine-driven liquefier to 1.93 kWh/L. The loss associated with this kind of liquefaction is estimated to 10% by Jones. Linde specifies a similar consumption of 2.0 kWh/L, but that assumes liquid N2 precooling, without this, the power consumption is 5.6 kWh/L. For cold-head or pulsed-tube-based liquefiers our estimates is based on datasheets from Bruker (12.1 kWh/L) and Cryomech (9 kWh/L), so we end up with an average estimate of 10.55 kWh/L. In brief, the numbers are as follows
Type Separation (kWh/L) Liquefaction (kWh/L) Loss (liq) (%) Transport (kWh/L) Total (kWh/L) gCO2e/L

Magnet boil off

Magnet boil off rates are estimated for different spectrometers. The report estimates the power consumption required for liquefying helium and nitrogen. The estimated power requirements are 7.43 kWh/L He and 0.5 kWh/L N. If He is liquefied locally, the national CO2 equivalents are used for the helium liquefaction, otherwise the World average is used, as it is difficult to predict in which country the helium is liquefied. Nitrogen is assumed to be liquefied locally.
1H frequency (MHz) Magnet temperature (K) Helium boil off (L/week) Nitrogen boil off (L/week) Source

CO2 equivalents

The amount of CO2 required to produce power depends on the source of the power production. In the present calculator we use a nation-wide average of the equivalents. The data comes from a report from the European Environment Agency and the database Our World in Data (all numbers from 2022).
Country CO2 equivalents (g/kWh) Source
The carbon calculator version is created by Thomas Vosegaard from the R-NMR report "Monitoring the carbon footprint (R-NMR Task 2.5)"

To Do

Change log

Version Date Changes
1.1.0June 15, 2024First public version based exclusively on the rNMR report.
1.1.1July 1, 2024Updated approach to calculate the power consumption of He liquefaction.
1.1.2August 28, 2024Added link to Our World in Data for country-wide CO2e/kWh.
1.1.3August 31, 2024Added link to and updated to the latest numbers for country-wide CO2e/kWh from the European Energy Agency data. In addition, the liquefaction numbers have been corrected for the remote supply by adding the separation contribution.
1.1.4October 23, 2024Fixed a bug in the detailed calculations where the contribution from the pump was included twice.
1.1.5January 28, 2025Activated local storage to remember settings from time to time.