Combined Heat and Power Combined heat and power (CHP) systems, also known as cogeneration systems, use heat engines or power stations to generate both electricity and usable heat at the same time. Thermal power plants emit heat when they create electricity, but this is often lost as waste and released into the environment through cooling towers or as flue gas. Combined heat and power makes use of this thermal energy for heating purposes, boosting energy efficiency and helping to save money. It can be used to heat buildings or create hot water. Cogeneration is found in many industries that require steam and electricity, such as paper mills, refineries and chemical plants. In these types of situations the steam can be used to dry paper, aid distilling or encourage chemical reactions. It is an efficient system because it uses the heat that is otherwise lost as waste. This means less fuel needs to be used as there is no need for a separate system to produce heat. To give the biggest benefits, combined heat and power should be used where there is a requirement for both heat and electricity at the same time. Heat energy is difficult to transport, whereas electricity can be sent to the national grid for others to utilise, so it is not so much of a problem if more electricity is produced than required. Combined heat and power systems are most efficient when the heat produced can be used on-site or nearby. Cogeneration plants are often found in district heating systems for cities, hospitals, prisons, wastewater treatment plants and industrial sites. Cogeneration systems can be run on carbon-based fuels such as coal and gas, as well as nuclear power or biomass. Micro CHP technology is becoming more common in the home and small offices, as they can help people lower their energy costs and boost efficiency, particularly if used in conjunction with solar panels.