4th generation district heating (4GDH) in developing countries: Low-temperature networks, prosumers and demand-side measures

Abstract

The aim is locating low-cost renovation measures to support the efficiency of district heating (DH). The topology analysis and GIS Zulu© are applied for hydraulic simulation and to verify the scenario viability. The scenarios are compared by life cycle cost, levelized cost of heat (LCoH), capital and operational costs, energy production and consumption, network length, heat losses, linear heat density, heat pump usage, peak load reduction, nominal power duration or the equivalent full load time. As demand-side measures (DSM), improved control, thermostats with an indoor temperature sensor and variable frequency drive (VFD) pumps reduce heat demand. Prosumer scenario imply installing a base-load heat pump. It means a consumer no longer receives heat from the DH system, because the households are now adapted to lower space heating (SH) supply temperature. Prosumer concept also allows placing a heat pump on the DH return line. The simplest configuration includes only the booster heat pump and domestic hot water (DHW) tank storages enough to cover morning or evening consumption peak. To limit piping cost, only supply and return pipes are considered for low-temperature DH, no additional (service) pipes or mixing valves are assumed. Converting single-family houses to prosumers decreases energy consumption, primary network flows and temperatures. LCoH ranges 19.7-35.4 EUR/MWh, depends on the decommissioned pipe length and its proportional pipe investment cost. LCoH decreases as the share of consumers converted to prosumers increases. Discounted payback time is 10 years for DSM and 41 years for prosumer case. For a base-load heat pump, the payback time is much higher than the reference scenario. It implies the same share of heat losses (16% of heat supplied from the CHP plant) with generally worse environmental and energy saving effect due to higher greenhouse gas (GHG) emissions and higher consumption of primary energy. Energy production is expected to follow the pattern of the useful energy consumption to compensate heat losses. The effects are decreasing residential heat demand (-4%), additional capacity to connect new consumers (+6%) and decreasing the network length.