These are busy times at the office of Ampyx Power, the Dutch company that designed the Ampyx Power Airborne Wind Energy System (AWES). After months of design optimisation, the team of Ampyx Power is currently assembling their third generation prototype, taking another step in the process of bringing the innovation to market. And while doing so, the fourth generation, which will form the basis for the scalable commercial model, is already on the drawing board.
Wind Energy Magazine No 4 – 2018
Expanding the operating envelope
Nowadays, we can see wind turbines all around us, on land but also at sea. Yet still, not all of the wind potential is used. Above 200 metres in the air, the current height limitation of conventional wind turbines, the harsh winds still remain untapped. The same goes for remote areas where, due to logistical challenges in the transport and installation of large and heavy components, it is economically not viable to install conventional wind turbines. Dutch company Ampyx Power claims to have found the solution to also harvest the wind at those locations, or as Pim Breukelman, Ampyx’ Commercial Director, says: ‘with our technology we can expand the operating envelope of wind energy.’
Ampyx Power’s AWES consists of an automatic aircraft which is tethered via cable to a winch on the launch and landing platform. The aircraft is launched into the air with a catapult and will perform autonomous flights in a regular cross wind pattern at an altitude from 200 metres up to 450 metres. When the aircraft moves, it pulls the tether and causes the winch to rotate and generate electricity like a dynamo. Once the tether is reeled out to a predefined length of about 750 metre, the aircraft automatically returns towards a lower altitude causing the tether to reel in. Then it ascends and repeats the process. All is done automatically, including launching and landing. An array of sensors provide the control system (autopilot) with the information which, in combination with pre-programmed parameters, are used to make decisions on next movements. There are three redundancy packages to guarantee continuation of the system, for safety in case of failure of one, but also to make sure that the data received from the sensors is triple checked.
The aircraft is light-weight due to the use of advanced composite materials. The wing consist of an internal structure of ribs and spars made out of a carbon epoxy laminate which are covered with sandwich panel skins containing a (Rohacell) foam core and glass fibre epoxy facings. The fuselages (twin configuration), that house the electronic systems, sensors, landing gear and propulsion systems, are also made of carbon epoxy. The prototype the company is currently building, the AP3, with a wingspan of 12 metres, weighs a little over 400 kg.
Long breath and determination
The project is a good example that it can take a long time and requires strong faith and persistence to bring an innovation to market. Ampyx Power is not there yet, but the end of the road is in sight. When Ampyx Power was founded ten years ago, their idea for airborne wind energy itself was not new. The idea of harvesting wind at higher altitudes appeared in scientific papers in 1930 and again in the eighties. However, the technology had never really been further developed into a practical concept until in 1997, when Dutch astronaut Wubo Ockels decided to start working on the concept at the University of Delft. He filed a patent under ‘Wind-driven driving apparatus employing kites’. He was joined by Richard Ruiterkamp, the founder and current CEO of the company. Together with 4 others Ruiterkamp founded Ampyx Power.
Today, the company counts some fifty employees. Around ninety percent of them are engineers who dedicate their time and energy on developing the technology towards a commercially viable product. Ruiterkamp concluded at an early stage that for commercial application a high performance rigid wing would have to be developed. The company is now working on AP3, the pre-commercial prototype, and their commercial system (AP4). Since the start they have developed and tested 8 prototypes. Walking around the premises, pictures and some of the actual early generation prototypes represent a diary of the past 10 years. Not all the prototypes survived. Ruiterkamp: ”Of the eight prototypes, three crashed. However, this was not due to the autopilot but the result of human errors.” And although this doesn’t make up for the loss of the aircraft, it does prove that the principle of an automatic operating process is working. This is the result of precise and meticulous recording of all the steps at all levels during the design phase, explains Breukelman. The company cooperates with Xignum, a company that has developed tailor made configuration management software for Ampyx Power. He adds: “If a change is made in one parameter, the system will show the effects on all other related parameters. Therefore we carefully define each step in the process and only deviate from the selected path when absolutely necessary.”
Start of assembly AP3
In 2015 Ampyx Power started with the design of the AP3, the pre-commercial model. Now the company has started building the prototype. While the interview took place, two sets of skins for the wings of the AP3 arrived at the workshop. The weeks following will be spent on assembling them. The total assembly process will continue into Q1 of 2019. Q2 will be used for system integration. In Q3 and Q4 the AP3 will undergo ground and runway tests followed by low wind tests. The autopilot will be tuned in tranquil conditions for autonomous and safe operation, before the system will be shipped to Ireland for full range testing with E.ON.
AP4 – preparing for market entry
And although the AP3 is not yet a commercial model, the lessons learned and data collected are invaluable to define and optimise the next generation, the AP4. All eyes will be on this model as it will determine the energy production capability, currently targeted at 2 MW, and therefore its commercial viability. The company has found a partner in energy company E.ON. In April 2017, both companies signed an agreement to work together whereby E.ON will facilitate and organise the sites where Ampyx Power can perform their full testing and verification program and the demonstration of both AP3 and its successor AP4. In 2020 the partners will run tests at a location in Ireland, in the County Mayo. Breukelman: ”We have looked at several locations large and remote enough to run the flights safely and where the wind conditions are harsh enough. We were just considering Australia when we found out about the location in Ireland. Site preparations will take place in the second half of 2019 so we can start our test flights in 2020.”
Window of opportunities
The AWES can be applied to different scenarios. Breukelman elaborates: “Our market entry is focused on the repowering business”. At the moment wind farms are decommissioned once the turbines reach the end of their service lives. With the AWES, the foundations and electrical infrastructure can stay in place and get equipped with a launch and landing platform for the automatic aircraft. Ampyx Power collaborates with utilities to explore onshore and offshore repowering opportunities, but is also looking at greenfield AWES projects. The final goal will be the floating wind energy market, he adds. “Here the benefits increase. Our model can be transported to the offshore site location from almost any port. Due to the weight and size of the components we are not restricted to the deepwater ports as is the case with the current floating wind turbine models on the market. Besides straight forward transportation and installation, the system is easier to operate. For maintenance we just land the aircraft on the platform.” The company already performed research on the technical viability and the costs of floating AWES. This was done in cooperation with research centres ECN and Marin and with Mocean, who designed a semi-submersible foundation.
As with all innovations of size, large amounts of investments are needed to bring an innovation from design to market. Ampyx Power uses a combination of own capital, equity, crowdfunding and subsidies. In fact, the crowdfunding, of which the first round was launched in 2013, turned out to be such a success that a second round was launched in 2017. Eight out of the total of € 30 million investment brought in up to now, was organised this way. As a result, around 600 participants are now co-owners in Ampyx Power. They are, and have been, kept up to date on the project by regular newsletters. The company will need another € 10 million to reach a fully verified AP3 model.
Beside the investments, Ampyx Power received funding from different subsidy schemes, such as Kansen voor West I and II, EC Horizon 2020 SME (for AP3) and from TKI Wind op Zee. TKI Wind op Zee granted subsidy for the research on the floating application, the design optimisation of AP4 together with Netherlands Aerospace Centre (NLR), and the research on the optimisation of the cable with DSM. There will be high tension on the cable as the aircraft moves in the air 24-7 and it should be designed to be most cost-efficient.
Lack of framework
There are still some steps to be taken. Airborne wind energy technology is still in its infancy, and, as of yet, there are no clear frameworks in the area of safety. Ampyx Power is working together with the European Aviation Safety Agency (EASA) regarding the establishment of clear certification standards for its AWES. Ampyx Power was one of the first companies worldwide to register a ‘Remotely Piloted Aircraft’ in a National Aircraft Register in 2013. From 2015 tethered aircraft have been categorized as a separate aircraft class by the EASA in European legislation for Remotely Piloted Aircraft (EASA NPA 2014-09). Also in the area of ecological impact assessment there are steps to be taken. Breukelman explains: “With the standard onshore wind turbines one can determine the impact on birds by counting the bodies on the ground beneath the turbines. But how can we count the collisions with airborne wind technology?” Research has taken place during the tests performed at Ampyx Power’s test site and a framework for ecological impact of AWES has been developed by Altenburg & Wymenga and Staatsbosbeheer. This framework will be used to further study the impact as soon as AP3 is operational.
Wind Energy Magazine will follow the developments of Ampyx Power.