Heating costs of most plants are only around 3 % of their total energy costs.

Plants with anaerobic sludge digestion

Power and heat co-generation supplies sufficient heat for the entire plant:

• If digesters and warm sludge pipelines are thermally well insulated,
• If raw sludge is sufficiently thickened.

Plants w/o anaerobic sludge digestion

Heating of buildings and hot water supply requires energy:

• Buildings should be thermally well insulated,
• Electrical heating should be avoided; where used, operation times should be limited with timers,
• Condensing boilers have an efficiency of over 100 % and safe fuel,
• Heat and power co-generation from natural gas can be economical and safes energy,
• Heat pumps extract heat from plant effluent and supply 4 to 5 kWh heat per kWh of power consumed (See our ThermWin Solution).

Plants with sludge drying

Thermal sludge drying consumes about 900 kWh per t of evaporated water:

• Waste heat, where available, should be used for sludge drying; our medium-temperature belt dryers KULT BT+ use co-generated heat;
• Heat for digester and building heating can be recovered from thermal sludge drying;
• If co-generation from digester gas should not supply sufficient heat for sludge drying, natural gas should be additionally used for cogeneration;
• At plants without anaerobic digestion, natural gas should be used for co-generation; heat is supplied for drying and power for plant operation.
• On-site sludge incineration also generates power and heat for drying.
• Solar dryers, such as HUBER SRT, consume no or little heat, but have a large footprint; they are smaller where heat pumps extract heat from plant effluent and supply it for sludge warming during drying.