Section 12O. There shall be established upon the books of the commonwealth a separate fund to be known as the Department of Telecommunications and Energy Trust Fund. There shall be credited to said fund all amounts collected pursuant to the second paragraph of section 18 and any income derived from the investment of amounts credited to the fund. All amounts credited to the fund shall be held in trust and shall be available for expenditure, without further appropriation, by the department of telecommunications and energy commission, for activities of the department related to the regulation of electric companies. Any unexpended balance in the fund at the close of a fiscal year shall remain in the fund and shall be available for expenditure in the following fiscal year.