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EnerTwin: A different approach to micro CHP

Periodic Reporting for period 2 - EnerTwin (EnerTwin: A different approach to micro CHP)

Reporting period: 2017-05-01 to 2018-09-30

Micro Combined Heat and Power (mCHP) systems are a perfect addition to stabilize the electricity grid in the increased presence of volatile renewable sources. Due to their efficient generation and local use of heat and electricity, their fuel saving- and CO2 reduction potential is tremendous. In spite of great interest of the market and policy-makers, currently available mCHP systems suffer from limited life, high investment and especially the very high maintenance cost, thus making them too expensive for serious market uptake.

MTT solves this problem with the EnerTwin, a mCHP system based on a micro gas turbine. The EnerTwin uses commercial off-the-shelf components resulting in potential low investment cost at larger volumes. Gas turbines are known for low-maintenance cost, their high power density (small size) and their long life. MTT uses automotive turbochargers as key components of the gas turbine: these are produced in millions and contribute to the low cost and high reliability of the EnerTwin. Gas turbines are inherently insensitive to varying fuel compositions facilitating use of various grades of natural gas.

In total 35 EnerTwin systems have been deployed in field tests at client locations since mid 2013. Besides the field-trial units, MTT has already sold first hundreds of commercial EnerTwins which promises an excellent future appearance on the market, while business options are under negotiation for high volumes. The EnerTwin has been developed from TRL 7 tot TRL 9 in this FTI project.

In this project, the readiness for commercialisation of the EnerTwin has been realised. MTT has improved the mCHP to meet CE and ECO Design requirements. In cooperation with clients, commercial pilots are being deployed. MTT has closed a substantial package of pre-orders for EnerTwins for the EU market through B2B agreements. On a daily basis B2B requests are coming in from all over the world, showing the high interest from the market in the EnerTwin.
Work carried out

Good results have been achieved in improving the efficiency and emissions of the EnerTwin up to and beyond the levels that are required to comply to ECO design 2018 norms. The design of the combustor has been further optimised and finalised. The efficiency of the permanent magnet generator has been increased and a design is made suitable for serial manufacturing. The design of improved power electronics for the EnerTwin has been proven to meet CE certification requirements and certificates have been obtained for compliance to grid connection requirements in most EU countries.

Design improvements were first lab-tested and after acceptance implemented and validated in EnerTwin field test units that were deployed at client location. Based on these field tests, use cases were evaluated for a number end-users. The fact that already a few of those end users have signed a first commercial sales contract proves they see a good business case for themselves with the EnerTwin. Further work on cost reduction of the EnerTwin for volume production will be an ongoing process. The production chain has been fully set up and MTT has contracted an assembly partner, ADDIT, in Venlo, The Netherlands. ADDIT employs 700 FTE and has production facilities in both the Netherlands and Poland.

Dissemination and exploitation activities have been carried out, following ongoing developments in the micro CHP market, ensuring that the EnerTwin is becoming well known in this market and to get the interest from potential B2B clients for the EnerTwin such as energy utilities (i.e. Stadtwerke in Germany), ESCO’s, installers and boiler manufacturers.

Project results achieved

At this moment, all the critical performance and emission improvements for the EnerTwin have been realised that are necessary meet Ecodesign requirements 2018. In Q1 2018, the EnerTwin received full CE-certification which proves compliance to EU safety, emission and performance requirements and allows MTT to commercially offer the EnerTwin to the market.
Novelty of the EnerTwin and technology

Smallest commercially available “micro” turbine is the Capstone C30 that delivers 30 kW electricity with over 10.000 units sold worldwide. Yet, 30 kW is way beyond the power requirement of MTT’s actual micro CHP markets. Reducing the output power, however, creates serious technical challenges: the negative effect of so-called tip clearances becomes more dominant leading to lower shaft efficiencies, rotational speed needed to achieve a reasonable efficiency raises exponentially, the hot parts (turbine wheel) and the parts that need to stay cool (compressor and generator) have to be placed at a very short distance causing unwanted heat transfer and resulting in lower performance or no performance at all. In addition, these technical challenges have to be solved within constraints of limits of materials and rotor dynamics.

With its micro gas turbine, MTT has solved these technical problems and developed a compact micro-gas-turbine using available turbocharger components (Commercial Off-The-Shelf). MTT has tested these micro gas turbines extensively, having operated them for long times without any measurable deterioration in materials and performance. Micro-CHP systems equipped with this micro gas turbine that were deployed in the field trials have proven to be very reliable. In addition, to the low-cost benefit of turbochargers, the main advantages of using a gas turbine for the EnerTwin micro CHP system are:
a) Gas turbines have only one single rotating part and require very little maintenance. From current stage of development, MTT can conclude that maintenance cost will be around 1,3 Eurocent per kWh electricity, which is only a fraction (< 20%) of maintenance cost of competing micro CHP systems. This maintenance is based on the full maintenance schedule and in agreement with specifications of subcomponents.
b) Gas turbines have a superior power density, allowing lightweight and small micro CHP systems to be built. This is important for low cost mass production, where material cost become a dominant factor.
c) Lifetime of gas turbines is substantially longer than that of other energy conversion technologies. As industrial gas turbines have a typical lifetime of 80.000 hours, the average reciprocating piston engine is generally designed for 5.000 to 6.000 hours. This increases the attractiveness of a micro turbine based micro CHP system, since condensing boilers (the benchmark device for EnerTwin) have a typical lifetime of more than 50.000 hours.

Reducing cost level, Total Cost of Ownership

MTT develops its products not with the sole aim of achieving high electrical efficiency, but with a strong focus on obtaining the lowest “Total Cost of Ownership (TCO)”. This approach is crucial for commercial success of micro CHP that will bring about all mentioned benefits for the society (energy efficiency, lower CO2 emissions, lower cost of energy etc.) achievable through a large-scale implementation of micro CHP.
MTT has translated this into a cost-effective solution: The EnerTwin offers a very reliable and more cost-effective micro CHP solution with a very competitive target price. In addition, with the low maintenance cost a payback time between 3 and 6 years for the end user in most EU member states will be possible.
EnerTwin in production at Addit BV - Venlo - The Netherlands
First commercial EnerTwins ready for shipment (april 2018)