Case Study Details - Future of Power Systems - Clean transition tariff (CTT)

A Clean Transition Tariff (CTT) is a utility rate structure that enables large electricity customers to support the procurement of new clean firm energy resources by agreeing to pay the cost associated with those technologies in exchange for rate credits based on the energy and capacity they provide. The model is intended to support system decarbonization by adding clean firm capacity that can operate during hours when variable renewable generation is insufficient.

Unlike traditional green tariffs that often source energy from least cost renewable projects, a CTT is designed to enable utilities to develop or contract additive clean resources – such as enhanced geothermal – that would not typically be selected under standard least-cost planning. The participating customer receives defined energy and capacity credits from the resource, while regulators oversee the tariff to ensure that non-participating customers are not exposed to additional costs. Because the tariff provides a clear cost-allocation framework, it can facilitate commercial arrangements for early-stage clean firm technologies that require greater revenue certainty.[1,2,3,4]

Main outcomes of the solution

Sustainability: Enables deployment of additive clean firm capacity that displaces fossil generation during high-emission hours. By allowing a large customer to fund the incremental cost of technologies such as enhanced geothermal, CTTs support progress toward hourly clean energy matching and reduce reliance on fossil generation.
Business Value: Provides a bankable pathway for large buyers to secure long-term clean firm supply with defined cost responsibilities and transparent energy and capacity crediting. This supports risk management for buyers while accelerating commercial maturity for emerging clean firm technologies.
Socioeconomic Impact: Protects non-participating ratepayers by assigning all premium costs to the participating customer, while supporting local economic development and workforce transition associated with advanced clean energy projects.

Key deployment and scaling factors:

Establish clear regulatory authority for utilities to create tariffs.
Secure large customers willing to make long-term commitments to new clean energy projects.
Ensure availability of emerging clean firm energy technologies at commercial demonstration scale.
Implement transparent cost-allocation mechanisms to balance customer benefits and system-wide impacts.

Case Study

Google, NV Energy (Berkshire Hathaway Energy) (2025), USA

Nevada’s Clean Transition Tariff was approved to allow a large customer to support development of a new clean firm resource while remaining fully served by the utility. In June 2024, Google and NV Energy asked Nevada regulators for permission to enter into a power supply agreement based on the proposed Clean Transition Tariff.

Under the arrangement, NV Energy procures energy from Fervo Energy’s 115 MW Corsac Station enhanced geothermal project and supplies it to Google under an Energy Supply Agreement structured within the CTT. The participating customer assumes the full cost associated with the project and receives defined energy and capacity credits on its electric bills, including credits that can offset demand charges.

The Public Utilities Commission of Nevada approved the tariff and related agreements in March 2025 after determining that the design prevented cost shifts to other customers. The case has informed similar tariff discussions in other jurisdictions considering customer-funded procurement of clean firm energy resources within regulated utility frameworks.[1,2,3,4]

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