Choose energy source to fit application

To convert one pound of water to vapor requires approximately 1,000 Btu. Choosing the correct energy source for this conversion not only depends on energy efficiency but on application specifics as well.

Boiler steam: Direct injection or steam-to-steam humidifiers
If there is an existing onsite pressurized steam boiler with available capacity, a cost-effective and energy efficient humidification method is to inject pressurized boiler steam directly into a space or ducted airstream.
Learn more: DriSteem pressurized steam products

Some owners object to direct boiler steam injection humidification because boiler water anticorrosion chemicals are emitted into the airstream with the humidification steam, creating a potential health hazard. To take advantage of on-site boiler steam while avoiding the disadvantage of boiler chemicals in the airstream, consider a closed loop steam humidification system, such as a steam-to-steam evaporative steam generator. A steam-to-steam system routes boiler steam through a heat exchanger located in a boiling chamber filled with clean water and creates clean humidification steam that doesn't contain boiler chemicals.
Learn more: DriSteem STS humidifier

Gas steam-to-steam humidifiers
Evaporative steam generators can operate using electricity or gas as energy sources. Historically, natural or LP gas humidification systems have provided significant energy savings over electric humidification systems. However, gas systems require flue venting and some require a sealed combustion air supply. If these requirements can be met, a gas fired evaporative steam generator is an cost-effective choice.
Learn more: DriSteem GTS humidifier

Electric steam-to-steam humidifiers
A significant advantage of electric resistive element or electrode evaporative steam generator systems is that they can be installed wherever power is available. Because of their relatively small size and ability to integrate into existing systems, electric humidification systems are used for many different application types.

Electric humidification systems can provide tight RH control - to within 1% of set point - achieved usually with an electric resistive element steam generator operating with solid state relay (SSR) control and using deionized (DI) or reverse osmosis (RO) treated water. This capability is critical for manufacturing processes requiring tight RH control. The many benefits of electric humidification, including lower upfront costs than gas humidification, frequently outweigh the typically higher energy costs.
Learn more: DriSteem electric steam humidifiers

Compare isothermal humidifier energy costs
Isothermal humidification systems use electricity or gas as an external heat source to change water to steam. An isothermal humidification system operating for one year in Minneapolis - with a 100 lb/hr humidification design load humidifying 13,000 cfm with 30% outside air to meet desired conditions of 69° and 40% RH - would produce approximately 290,000 lb of humidification steam in one year. The Energy Information Agency lists average industrial utility rates for Minnesota (as of July 2005, the most current rates available at this writing) to be $0.056/kWh for electricity and $7.15/1,000 cu ft for natural gas.

Based on these rates, and adjusted for typical evaporative steam generator efficiencies, the energy cost to humidify the space described above for one year is approximately $5,600 using an electric evaporative steam generator and approximately $2,750 using a gas-fired evaporative steam generator, a significant savings. Given the fluctuating nature of energy costs, the easiest and most accurate way to compare electric and gas humidification energy costs is to use a humidifier manufacturer's energy calculation program that creates a customized report based on your local energy rates.
Learn more: DriSteem EnergyCalc software

Adiabatic (unheated water) humidifiers
An alternative to isothermal humidification is adiabatic humidification. Adiabatic systems such as high-pressure atomization and wetted media systems disperse water droplets or fog into air that has enough latent heat energy to cause dispersed water to change state to vapor. As the dispersed water or fog changes state, air temperature drops, and RH increases.

Adiabatic humidifiers utilize a variety of technologies to introduce water into air, either by dispersing water droplets or by allowing water to evaporate from a wetted media, causing relative humidity (RH) levels to increase and air temperature (dry bulb) to decrease.

Perhaps the most touted benefit of adiabatic humidification is air cooling. Because adiabatic humidifiers draw heat from air for evaporation, they can produce a 20°F or more temperature drop. In fact, every pound of adiabatic humidification added to air removes approximately 1000 Btu of heat. Twelve pounds of water added as humidification equals about one ton of cooling. This is a significant benefit in climates where air is consistently warm and dry, or in spaces where there is an additional heat load such as from equipment in a computer room. 
Learn more: DriSteem High-pressure system