Bremerhaven offers a wide range of accommodation options, from rather upscale hotels (e.g., Atlantic Hotel Sail City, right "on top of" the Klimahaus) to family-run, small scale hotels. Many of them are clustered around the area of Klimahaus, museums etc. -  the quarter called "Havenwelten". 

Since the conference will take place outside of the main holiday season, the demand for accommodation should not be too high, and we have abstained from trying to negotiate dedicated rates for the conference.  But of course, we recommend booking early anyway. The best way will be your favorit booking portal, your institution's travel agency, or the Bremerhaven tourism website