Ultra-Dense Wavelength Division Multiplexing (UDWDM) has been proposed for the optical access Passive Optical Network (PON) in the COst-effective COhereNt Ultra-dense-WDM-PON for lambda-To-the-user access (COCONUT) project, introducing the wavelength-to-the-user concept. A low-cost high sensitivity coherent detection technique furnishes high splitting ratios and long-reach extension. ONU coherent transceivers employ lasers with wavelengths randomly distributed and densely spaced in the optical band, but owning limited tunability. The wavelength channels are allocated using heuristic Dynamic Wavelength Assignment (DWA) algorithms. These schemes are applied not only in activation processes, but also during operation under environmental conditions, adapting the laser tuning to provide the required assigned channel. The laser tuning is achieved by heating or cooling control, and the power consumption varies depending on the wavelength position in a tuning window. We evaluate and compare the power consumption of the developed DWA schemes in the network, as energy efficiency is important to reduce the green-house gas emissions. © 2016 IEEE.