Heat from CHP can pass through a plate or other suitable heat exchanger into a separate heat-network circuit. At the other end, customers receive hot water for space heating, domestic hot water or their own processes. The biogas plant remains hydraulically and operationally separate from its heat customers.
Demand profile matters more than pipe diameter
A residential area needs substantial heat in winter and little in summer. A hospital, care home, hotel, swimming pool or food-processing plant may have much steadier year-round demand. Assessment therefore needs to consider the megawatt-hours customers can actually use over 8,760 hours, not just peak capacity.
Distance quickly changes the economics
Longer routes increase the cost of pre-insulated pipes, excavation, road crossings and pumps, as well as heat losses. A short connection to a large customer is usually simpler than a long network serving many small users. Land ownership, utility corridors and the scope for phased expansion need particular attention.
Thermal storage adds flexibility
CHP generation and heat demand rarely follow exactly the same pattern. A thermal storage tank can hold surplus heat when demand is low and release it when demand increases. This reduces the need for the engine to follow momentary heating demand and makes the system more resilient to short-term variation.
Who could be a suitable heat customer?
- a settlement or group of residential buildings
- a school, sports hall, swimming pool or care home
- a farm, poultry house or greenhouse
- a workshop, logistics centre or business park
- industry with continuous hot-water demand
Examples in practice
INNIO Jenbacher has published examples of CHP plants supplying local heat networks. In Memmingen, for example, a biogas-fuelled CHP unit is integrated with thermal storage and local heat supply. The network itself uses established components: pre-insulated pipes, pumping stations, heat exchangers, meters and controls.
What must be agreed before construction?
The project is commercial as well as technical. Heat pricing, minimum or expected offtake, metering, responsibility for backup heat, CHP outages and future changes in demand all need to be agreed. Without identified customers and a long-term payment model, even a well-routed pipe network can become costly infrastructure with inadequate revenue.
Sources and further reading
- INNIO – Green Airport Memmingen and biogas CHP
- European Commission – study on district heating and cooling
- U.S. EPA – What Is CHP?
This article is for information. An actual installation requires a heat balance, equipment manufacturer data and checks of local conditions, permits and applicable regulations. The illustration shows a functional concept, not a detailed engineering design.