
December 31, 2024	Weighted Average Amortization Rate		Cost	Accumulated Amortization	Net
(millions of Canadian dollars)
Software	10.9	%	2,109	(1,222)	887
Power purchase agreements	4.5	%	58	(26)	32
Project agreement1	4.0	%	173	(52)	121
Customer relationships	8.6	%	2,856	(975)	1,881
Biogas rights agreements	3.4	%	999	(34)	965
Other intangible assets	5.8	%	665	(234)	431
Under development	—	%	270	—	270
			7,130	(2,543)	4,587


December 31, 2023	Weighted Average Amortization Rate		Cost	Accumulated Amortization	Net
(millions of Canadian dollars)
Software	12.0	%	1,921	(1,090)	831
Power purchase agreements	4.3	%	58	(24)	34
Project agreement1	4.0	%	158	(41)	117
Customer relationships	8.6	%	2,636	(675)	1,961
Other intangible assets	8.2	%	603	(185)	418
Under development	—	%	176	—	176
			5,552	(2,015)	3,537

1Represents a project agreement acquired from the merger of Enbridge and Spectra Energy.

For the years ended December 31, 2024, 2023 and 2022, our amortization expense related to intangible assets totaled $530 million, $535 million and $483 million, respectively. Our expected amortization expense associated with existing intangible assets for each of the years 2025 to 2029 is $558 million.