Mother Nature has an arsenal of weapons that can knock out the power for several days and imperil businesses that rely on computers. The northeastern snowstorm that knocked out power to 170,000 customers for several days in April demonstrated how severe weather events can put a small or mid-size business offline for an extended period. A variety of scenarios -- including upcoming summer heat waves and hurricane season -- have the potential for crippling businesses that have become reliant on technology.

Experts say that a backup power system that includes both uninterruptible power supplies (UPS) and a power generator will keep critical servers running when the power grid falters.

A UPS is needed because generators take too long to respond to a power failure, according to Farah Saeed, a senior consultant at Frost & Sullivan. A generator alone is not sufficient because it takes 30 seconds to a minute to start, Saeed says.

How UPS works with power generators

The UPS provides temporary power until the generator goes online, commonly offering a 10 to 20 minute buffer, while some models can last for as long as four hours. UPS systems are rated to match the power requirements needed to keep computer equipment functioning, and are measured in kilowatts (kW) and kilo volt-amperes (kVA).         

When the UPS detects that the backup generator is ready, the UPS automatically switches the power source to the generator. Many computer vendors including Dell, IBM and Hewlett-Packard partner with UPS companies to simplify finding an appropriate UPS system when you order business computers.

Generators most commonly provide two to three days of power, or they can be built-to-order to last longer, according to Eric Johnston, chief executive officer of Americas Generators, a global supplier of generators based in Miami, Fla. Johnston says generators range in price from $10,000 to more than $500,000 to backup a large data center. Businesses also should plan for significant installation costs -- installing a generator can adds 50 percent to more than 100 percent to the cost of the equipment.

Costly powering mistakes

Johnston says the biggest mistake that companies make when buying a generator setup is insufficiently planning for the future. If you know your business will be expanding its use of computer and server equipment, buy a bigger generator up front. "Moving up in size [of a generator] doesn't equal the added cost," says Johnston, adding that companies who later expand their computing platforms will pay a significant premium to upgrade their generating equipment, especially if the existing equipment has to be removed.

When determining the size of a generator setup, businesses also must consider the amount of power required by the supporting heating, ventilating and air conditioning (HVAC) system. Computers can fail if the temperature in the room gets too cold or hot, so business that have access to the HVAC system should integrate their power requirements into their backup system.

Diesel and natural gas generators are viable choices for backup power. But for computing systems that require more than 200 kW of power, diesel generators are preferred because they use less fuel. While diesel is more energy efficient and costs less to fuel, natural gas generators burn cleaner and can be less expensive to purchase. Fuel cell generators, which gained attention for using clean-burning hydrogen, have nearly disappeared from the market because of the high cost to fuel, according to Johnston.

Businesses that occupy rental properties can purchase portable generators to reduce the time and cost of installing a backup system. For example, tenants of office buildings with leases that limit modifying the existing structure or in areas where getting building permits is difficult may find it easier to rent a mobile generator housed in a trailer, Johnston says. Mobile generators are less costly to install (only 15 to 20 percent of the equipment price), and can also serve as a backup for multiple locations.