Backup diesel generators, particularly those used in the technology industry to ensure an uninterrupted power supply at large internet data centers, have recently come under heavy scrutiny from state environmental authorities. This heightened scrutiny is likely to lead to an uptick in enforcement activity by state and federal environmental agencies, making this a critical time for data center operators to ensure that backup power sources comply with all applicable environmental regulations. Many of the environmental compliance concerns confronting internet data centers today are similar to issues that have previously been confronted on a somewhat smaller scale in the build out of cellular communications and satellite television signal transfer infrastructure.

Although air permitting requirements vary from state to state, under the federal Clean Air Act, a permit or other form of authorization is usually required prior to installing and operating diesel generators. Even where the air emissions from backup power generators are properly authorized, limitations on hours of operation are common. For example, in certain parts of Texas, new stationary diesel engines are exempt from emissions standards only if they are operated for less than 100 hours per year, including required testing. Separate federal performance standards and limits on hazardous air pollutants may also apply to limit the operation of backup diesel generators.

In addition to requirements related to air emissions, under the federal Emergency Planning and Community Right-to-Know Act businesses are required to notify state agencies and local fire departments of certain chemicals at their facilities, if these chemicals, including diesel fuel, are stored in amounts above threshold quantities. Also, under the federal Clean Water Act and state analogues, companies that handle, transport, or store diesel fuel or other oil or petroleum fuels may be required to prepare and periodically update spill prevention, control and countermeasure plans in order to set out best practices for containing spills and preventing hazardous chemicals from polluting water bodies. Finally, at sites that store diesel fuel for backup generators in underground storage tanks, the federal Resource Conservation and Recovery Act requires that certain steps be taken to prevent leaks, and, in some cases, that tanks be upgraded.