LEMENE – Lempäälä energy community

LEMENE is a self-sufficient energy system completed in 2019 located in Marjamäki, Lempäälä. The project was one of the flagship initiatives of Ministry of Economic Affairs and Employment of Finland for new technologies, and it represented a unique system on a national scale. LEMENE is a comprehensive system that utilises renewable energy sources and operates independently. It has the capability to operate as a stand-alone power grid without a power outage.

Lemene system

The area includes six substations, which form a ring network. The system consists of solar panels, gas engines, electricity and district heating energystorages, as well as fuel cells. The entire energy system is controlled by a microgrid controller, capable of forecasting and optimising production while considering conditions and regulating consumption.

The LEMENE energy system is built sustainably in line with future demands, and the system can be integrated with new production units and forms as well as consumption. LEMENE aims to secure the energy supply for the area and act as a forerunner in decentralized, renewable energy production. The development work has done in cooperation with local university.

The virtual power plant solution combines different production types to form a single system

Microgrid controller

The Microgrid Controller (MGC) operates as a control and optimisation system for electricity and heat production, controlling the production units of the LEMENE microgrid. The MGC predicts renewable energy production (solar energy), electricity and district heating consumption. In addition, the system is provided with forecasts for the electricity market prices for the following day. Based on this information, calculations are made to determine the most cost-effective production type for producing district heating. The remaining capacity is offered to the national reserve market to support the balance between consumption and production in the electricity network. The system’s operation and communication with the electricity markets is done automatically.

Solar power plants

The combined nominal power of our two solar power plants is 4 MWp, and their annual production amounts are approximately 3.5 GWh of renewable energy. In total, there are over 13,200 solar panels. The solar power plants were the first to be commissioned in the LEMENE energy system in late summer 2019 and were the first solar power plants of this size in Finland.

Combined heat and power production

Gas engines are used for combined heat and power production. The total power of gas engines within LEMENE is 8.1 MW, and there are a total of six gas engines. Bio- or natural gas is used as the fuel for gas engines. The generators of the gas engines produce electricity, and the thermal energy generated by the engines is used in the district heating network. The gas engines are controlled by a intelligent microgrid system (MGC) and participate in reserve markets.

Smart grid and electricity energy storage system

An Important part of the LEMENE energy system is ensuring the quality and availability of electricity, especially as renewable energy production fluctuates. A key part of the system is a 4 MW electric battery, which among other functions takes a part in stabilizing momentary power changes in the solar panel field. The battery participates in reserve markets to maintain the balance of the national power grid’s production and consumption. Due to their diversity and speed, electric batteries are a fundamental component of microgrid management.

To maximize usability, the Medium-Voltage Network is built as a ring network. The network features a smart protection system implemented with safety relays, ensuring fast and reliable fault detection and resolution.

The system primarily operates as part of the public power grid, but when needed, it can also function as a reserve system ensuring the national power grid’s power balance or as an independent island grid. This capability is made possible by electric batteries and automation solutions applied in microgrid management.

Fuel cells

Fuel cells are electrochemical devices that use hydrogen as their fuel. Efficient and low-emission fuel cells can be used in decentralized electricity and heat production systems. In Lempäälä, next-generation fuel cells have been commissioned use for the first time in Finland. Two combined heat and power (CHP) fuel cell systems have been integrated into the Marjamäki smart grid, featuring next-generation solid oxide fuel cells. The combined power output of these two separate cells is 130 kW.