Aladin II - Micro Combined Heat and Power Plant (mCHP)
Recent energy policies smooth the way for future strategies that are partly based on various renewable energy sources, such as solar or wind. However, these sources are strongly dependent on environmental factors. In this context, decentralized power generation with combined heat-and-power (CHP) units becomes increasingly popular, as those units do not only maximize energy efficiency by providing heat and power as close as possible to the consuming household, but are also able to provide regulative power to the electricity distribution network. The research project “ALADIN II” deals with the development of a micro combined heat and power plant (mCHP) which is not only highly efficient and highly flexible, but emits near-zero pollutant emissions.
This project is a collaboration between external page Bucher AG Langenthal (Motorex), external page Hoval Aktiengesellschaft, external page sa-charging solutions, and ETH Zürich (IDSC & LAV).
It is funded by the Swiss Federal Office of Energy (external page SFOE) and the Swiss Competence Center for Energy Research - Efficient Technologies and Systems for Mobility (external page SCCER-Mobility).
Why CHP?
In light of the energy transition, more and more renewable energies contribute to the electricity mix. Some of these have an intermittent availability, e.g. solar or wind. In case of local weather phenomena, this increases the risks of having power outages. Combined heat and power can address this issue. The energy generation is decentralized such that consumers produce their own thermal and electrical energy. This not only minimizes transport losses, i.e. increases the efficiency, but also support grid stabilization if needed. CHP plants exist in different scaling level and are therefore available for industrial as well as private consumers.
Why research on CHPs, if they are already on the market?
First, the return-on-investment increases with the CHP size. Investment costs for large CHPs are typically amortized after very few years. This is why only very few small CHPs (micro and mini class) are available on the market. Thus, increasing the economic benefit of a micro combined heat and power plant is one of the key research areas. The other one is, naturally, the minimization of the pollutant emissions. Whereas many commercial CHPs are designed to just meet the governmental emission regulations, this project is focused on demonstrating the potential for emission reduction with cost-effective hardware and software solutions.
Project Vision
- Near-zero emissions
- High total efficiency
- High operational flexibility
- Fast load uptake
Performance Targets
- 5-10 kW electric power and high electrical efficiency
- Near zero steady-state pollutant emissions
(< 10 mg/Nm3 for NOX, CO, Total Hydrocarbons (THC)) - Low cold-start pollutant emissions
- Compact design
- Low investment costs
- Low maintenance and long lifetime
Plant Design
The mCHP plant is powered by a 1-cylinder spark-ignited combustion engine with 325 ccm displacement volume. The engine has been adapted to run on natural gas. The exhaust gas flows through a three-way catalytic converter in order to remove the combustion residues. The engine always operates at full load. It drives an asynchronous generator that produces the electrical energy. This electrical energy can then either be used directly on site or, if there is no power demand, it can be fed to the electricity grid for a compensation according to the effective feed-in tariff.
Hot water is typically supplied at temperature levels around 80°C to the thermal energy storage (TES). This thermal energy is generated via two paths. First, the hot exhaust gases are routed through a shell-and-tube heat exchanger and, thus, heating up the water mass contained in the shell. Second, thermal energy is transfered from the engines cooling circuit via a plate heat exchanger. Thus, compared to an automotive context, the heat removed from the engine is not released as waste-heat to the environment, but utilized to produce the plants' thermal energy output.
