Full steam ahead for decentralized power
Waste heat from industrial processes, cooling and combustion systems has been an underutilized energy source – until now. Help is at hand with the ePack system from Orcan Energy, which is ideal for capturing energy from smaller volumes of heat, such as those produced by combined heat and power plants. Control technology from B&R makes a significant contribution to the highly efficient performance of the ePack micro power plant and allows it to be operated unmanned and at partial load.
Every second around the globe, enormous quantities of unused energy are pumped into the atmosphere in the form of waste heat. Power stations, private furnaces and motor vehicles that burn fossil fuels only utilize around a third of the total energy released. The same is true of biogas, where the efficiency is still only around 40 percent, despite the advanced technology used. The remaining 60 percent of the energy contained in the fuel is released as heat. Until now, this thermal energy has only been used to a limited extent, for example in district heating networks. Due to a lack of consumers, it is often the case that only 10 percent of waste heat is used to heat the fermenters in the biogas systems and the on-site agricultural buildings.
Turning this untapped thermal energy into a commercially viable resource was the motivation for Munich-based Orcan Energy to develop its ePack micro power plant. "The ePack uses ORC technology, which makes it possible to generate electricity from heat. In comparison to traditional steam turbines, this process works at considerably lower temperatures and lower levels of thermal energy," explains Detlef Eissing, sales and marketing manager at Orcan Energy.
ORC technology itself is not new, however. A number of different plants across Germany are already generating electricity from waste heat using the Organic Rankine Cycle (ORC). Unlike conventional steam turbines, the ORC process doesn't use water as its heat transfer medium. Instead, it uses organic materials such as ammonia, butane or pentane, which have a significantly lower boiling point than water and allow the system to operate at temperatures between 80 and 500°C.
Despite this, ORC plants have only ever been used in a small number of highly specialized applications. "The fact of the matter is that each one of these plants had to be customized to suit the specific requirements of the application. This means that entire components or sections of the plant needed to be redesigned or redeveloped each time," says Eissing. "While this might help us boost efficiency by a couple of percent, it drastically increases the cost of the systems, reducing their cost-efficiency in applications with small heat sources or low temperatures. This is generally the case with stationary or mobile combustion engines, heating systems or cooling plants."
Batch production with standard components
In developing the ePack, Orcan made the decision to use existing technologies and components which are easy to modify. This means the company didn't have to develop its own steam turbines, instead relying on mass-produced compressors normally used for refrigeration. "This allowed us to significantly reduce the investment costs for ORC systems. Moreover, it provides both us and our customers with the assurance that the components are reliable and won't be beset by initial teething problems," stresses Eissing.
This is why Orcan also uses tried and tested products when it comes to control technology. The ePack uses a B&R Power Panel 65 touch screen HMI for control and visualization. "When we were researching potential technologies, B&R stood head and shoulders above other suppliers of control systems," explains Jens-Patrick Springer, a mechanical engineer who was closely involved in the development of the ePack. One of the key factors in choosing the B&R solution was the high-quality construction of the Power Panel, which offered the optimal amount of processing power for the application.
Cost savings thanks to B&R technologies
The control system communicates with the various ePack components using a range of I/O modules from the X20 system. This allows it to measure temperature, pressure and heat volume, read error messages and regulate the speed of the generator, condenser and feed pumps. "All of the potential solutions we looked at were able to measure the temperature," says Springer. "The difference was in the cost per measurement. B&R really stood out in this respect."
However, because Orcan Energy was still using control technology produced by other suppliers in the initial prototypes used for demonstration and development, there were fears that making a switch would delay the ePack's roll-out. "Any concerns we had were quickly put to rest," recalls Springer. "With basic programming skills we were immediately up and running. The Automation Studio development environment provided us with everything we needed. Assisted by training and support from B&R engineers, we were able to develop the basic structure of the control software in a matter of weeks.
High efficiency, even at partial load
Since then, the sophisticated and constantly evolving control system, which is used in conjunction with specially-designed Orcan plant technology, ensures that the ePack can adapt to fluctuations in the level of available thermal energy without any human intervention. "Many other ORC plants can't be operated automatically; they need human operators and are slow to react to fluctuations in the energy supply. As a result, the efficiency of these plants deteriorates noticeably when they are operated at partial load," notes Springer.
Eissing explains that with the ePack, the efficiency remains fairly constant over a broad range, even if the supply of energy is reduced. "If only 50 percent of the anticipated heat is being supplied, our equipment automatically switches into partial load mode. Even in this mode, the ePack still manages to return almost half of the rated output."
This is also significant for combined heat and power plants with a rated output of 450-500 kW and for stationary engines, for which the compact ePack – measuring 2 x 2 x 1.2 m (L x H x W) and delivering a thermal power of 300 kW and electrical output of 20 kW – is ideally suited. Eissing goes on to say that, "Even in biogas plants, the combustion engine fluctuates more than you might first expect. For example, the fermentation process runs differently in summer due to the higher outside temperatures."
"B&R prevailed in our search for a control systems partner. What convinced us was the outstanding quality of the Power Panel, the user-friendly engineering environment and the company's philosophy of innovation. Our positive experiences with the technology combined with the excellent service convinced us that B&R was the right choice." Jens-Patrick Springer, Developer, Orcan Energy GmbH
Thanks to the relatively low investment and the high efficiency even at partial load, Orcan systems generally pay for themselves within a few years. "With a combined heat and power plant running for around 7,000 to 8,000 hours, we can already achieve generation costs of less than 5 cents per kilowatt-hour and secure this for 15 years," says Eissing proudly.
These figures have won over customers in a host of different sectors. In 2013 alone, Orcan sold 15 ePacks. "This success is unquestionably owed to our basic principle: supply the right device at a competitive price," explains Eissing.
But for the head of marketing, the finish line is still some way off. Orcan believes it will be possible to achieve annual sales of 1,000 of the 20 kW ePacks in the medium-term, and that in the future users will benefit even more from the savings due to larger scale production.
B&R – the right choice
Springer notes how B&R has fully supported Orcan's efforts to make ORC systems even more economical and broaden their range of applications. "As an innovative company, B&R constantly monitors the latest trends and is quick to establish new ones. This is a clear benefit for our users."
The ORC expert was very pleased with the introduction of the M-Bus communication module (X20CS1012) that provides developers access to a wide range of measurement devices, as well the energy measurement module (X20AP3131), both from the X20 system.
Prior to the introduction of the energy measurement module, Orcan had the added time and cost of integrating separate measurement instrumentation. Now the energy measurement module is right on the DIN rail as an integral part of the control system. "For us this means easier installation, smaller space requirements and lower overall costs," says Springer. "This also confirms to us that we made the right choice in working with B&R and that we are on the right track towards our goal of improving the energy balance of combined heat and power systems and stationary combustion engines."
Using Automation Studio, the experts at Orcan Energy were able to develop the whole basic structure for the ePack power plant in a matter of weeks. The transparency of the system allows it to be quickly adapted to higher level system controls and there are no limits to the ongoing development of the control system.