Your question puzzled me. Germany consumed 130TWh of natural gas in January 2022, mostly for heatinghttps://www.bundesnetzagentur.de/EN/Areas/Energy/Companies/SecurityOfSupply/GasSupply/grafik_consumption.html
so 1GW over 1 year saves 9TWh or 2 January days worth of natural gas
Natural gas costs 15€/TJ (0.05€/kWh) at the borderhttps://www.eek-energy.com/en/news/natural-gas/detail/news/gas-import-price-rushes-from-record-to-record.html
so 1GW over 1 year lets save 0.5G€/year
, which is indeed better than nothing.
Or you can compare with a present lengthy and passionate debate in Germany about closing TWO nuclear power plants right now, or in January, or keeping them in operation longer. The unhealthily wasted sucrose is ONE power plant worth.
Though in my view, it's better to sell or give the food to hungry people than burning it.
What's your geothermal system? Do you have a hot source, or do you use the ground's inertia for heating and cooling, combined with a heat pump maybe?