INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Provision for Income Taxes

The provision (benefit) for income taxes from continuing operations consisted of the following:
	Year ended December 31,
	2021		2020		2019
	(thousands of dollars)
Current federal benefit	$	(552)	$	(19,190)	$	—
Current state expense	173		86		91
Deferred federal expense (benefit)	(1,910)		15,140		(3,564)
Deferred state expense (benefit)	(75)		1		(93)
Income tax expense (benefit)	$	(2,364)	$	(3,963)	$	(3,566)

Schedule of Effective Income Tax Expense (Benefit)

The difference between the year ended effective tax rate in income tax expense (benefit) and the Federal statutory rate of 21% is as follows:

	2021		2020		2019
	(thousands of dollars)
Income taxes at U.S. statutory rate	$	546	$	211	$	(3,455)
State taxes, net of federal benefit	62		71		256
Forgiveness of PPP Loans	(1,286)		—		—
Net operating loss carryback	—		(4,655)		—
Research and development credits	—		(518)		(203)
Permanent and other items	(1,686)		928		(164)
Total tax benefit	$	(2,364)	$	(3,963)	$	(3,566)

Tax Effects of Temporary Differences

Tax effects of temporary differences that give rise to significant portions of federal and state deferred tax assets and liabilities were as follows:

	December 31,
	2021		2020
	(thousands of dollars)
Deferred tax liabilities:
Plant, pipeline and equipment	$	(31,126)	$	(31,119)
Other assets	(29)		(31)
Operating lease asset	(1,712)		(2,211)
Total deferred tax liabilities	$	(32,867)	$	(33,361)
Deferred tax assets:
Net operating loss carryforward	1,836		—
Intangible assets	3,079		3,396
Operating lease liability	1,712		2,211
Stock-based compensation	1,070		956
Mineral interests	—		226
Interest expense carryforward	253		—
Inventory	263		146
Other	129		135
Gross deferred tax assets	8,342		7,070
Valuation allowance	—		(226)
Total net deferred tax assets	$	8,342	$	6,844
Net deferred tax liabilities	$	(24,525)	$	(26,517)