Our financial relationships with our member distribution cooperatives are based primarily on our contractual arrangements for the supply of power and related transmission and ancillary services. These arrangements are set forth in our wholesale power contracts with our member distribution cooperatives that are effective until January 1, 2054, and beyond this date unless either party gives the other at least three years notice of termination. The wholesale power contracts are all-requirements contracts. Each contract obligates us to sell and deliver to a member distribution cooperative, and obligates that member distribution cooperative to purchase and receive from us, all power that it requires for the operation of its system, with limited exceptions, to the extent that we have the power and facilities available to do so.

An exception to the all-requirements obligations of our member distribution cooperatives relates to the ability of our eight mainland Virginia member distribution cooperatives to purchase hydroelectric power allocated to them from SEPA, a federal power marketing administration. We estimate that purchases under this exception constituted less than 2.0% of our member distribution cooperatives’ total energy requirements in 2021.

There are two additional limited exceptions to the all-requirements nature of the contracts. One exception permits each of our member distribution cooperatives, with 180 days prior written notice, to receive up to the greater of 5% of its demand and associated energy or 5 MW of demand and associated energy from owned generation or other suppliers. Such load can be returned to us with proper notice. The other exception permits our member distribution cooperatives to purchase additional power from other suppliers in limited circumstances following approval by our board of directors. As of December 31, 2021, none of our member distribution cooperatives had utilized this latter exception.

If all of our member distribution cooperatives elected to fully utilize the 5% or 5 MW exception, we estimate the current impact would be a reduction of approximately 178 MW of demand and associated energy. The following table summarizes the cumulative removal of load requirements under this exception.

We do not anticipate that the current or potential full utilization of this exception or the return of load by our member distribution cooperatives will have a material impact on our results of operations, financial condition, or cash flows.

Each member distribution cooperative is required to pay us monthly for power furnished under its wholesale power contract in accordance with our formula rate. We review our formula rate design at least every three years to consider whether it is appropriately achieving its intended results. The formula rate, which has been filed with and accepted by FERC, is designed to recover our total cost of service and create a firm equity base. See Note 1—Summary of Significant Accounting Policies—Formula Rate.

More specifically, the formula rate is intended to meet all of our costs, expenses, and financial obligations associated with our ownership, operation, maintenance, repair, replacement, improvement, modification, retirement, and decommissioning of our generating plants, transmission system, or related facilities; services provided to the member distribution cooperatives; and the acquisition and transmission of power or related services, including:

The rates established under the wholesale power contracts are designed to enable us to comply with financing, regulatory, and governmental requirements that apply to us from time to time.

Revenues from our member distribution cooperatives for the past three years were as follows:

	Year Ended December 31,
	2021		2020		2019
	(in millions)
Rappahannock Electric Cooperative	$	223.3	$	237.6	$	279.7
Shenandoah Valley Electric Cooperative		138.2		144.5		168.4
Delaware Electric Cooperative, Inc.		109.1		110.0		121.6
Choptank Electric Cooperative, Inc.		72.1		73.7		83.1
Southside Electric Cooperative		51.8		56.9		69.8
A&N Electric Cooperative		44.0		48.0		54.7
Mecklenburg Electric Cooperative		32.6		36.8		45.1
Prince George Electric Cooperative		20.2		22.9		26.9
Northern Neck Electric Cooperative		16.9		20.2		24.1
Community Electric Cooperative		10.5		11.0		14.1
BARC Electric Cooperative		8.2		9.2		11.0
Total	$	726.9	$	770.8	$	898.5