You can start here:

https://www.oecd.org/tax/tax-policy/environmental-tax-profile-denmark.pdf

Go to OECD.Stats -> Environment -> Environmental policy -> Enviromental-related tax revenue.

There, you will be able to find the national sources, too:

https://www.oecd.org/environment/indicators-modelling-outlooks/policy-instrument-database/

http://stats.oecd.org/wbos/fileview2.aspx?IDFile=813ced8d-4560-4c43-9b2c-413d017bee9e

You may want to check the website of The Danish Environmental Protection Agency (EPA) for more information, as follows:

https://eng.mst.dk

https://www.oecd.org/tax/tax-policy/environmental-tax-profile-denmark.pdf

https://data.europa.eu/data/datasets/data-on-taxation-in-denmark?locale=en

https://knoema.com/env_ac_tax/environmental-tax-revenues?geo=1002140-denmark