Volume 3, Issue 1 - Energy Transition – Energiewende (Part 1 of 2)

Molten salts have been widely considered as the leading candidate heat transfer fluids (HTF) used in high temperature, concentrated solar power plants. Specifically, nitrate and nitrite based salts have been investigated as a HTF and even deployed in pilot plants generating up to 19.9 MW of electricity at operating temperatures above 500 °C. New plant designs requiring higher operating temperatures for better efficiencies are pushing the stability limit of HTF. This paper presents an overview of the thermophysical properties of nitrate and nitrite salts and discusses thermodynamic and kinetic stability limitations as they relate to concentrated solar power generation.

Using renewable energies means having to deal with a strongly stochastic behaviour, since for photovoltaics the sun has to shine or for wind generators the wind has to blow. For being able to supply the load any time, storage solutions are needed. Decreasing costs and better availabilities of new battery technologies like lithium-ion therefore result in a growing demand for more sophisticated battery systems in off-grid and grid connected applications. In e.g. off-grid applications, lead-acid battery systems are state of the art. Though, lithium-ion batteries become more popular because of their high energy density and long life time. Another application for electrochemical storage systems are electric vehicles. In all those cases the battery storages need to be managed. But the management of a battery system is not a trivial problem. The batteries must be monitored and controlled, there are challenges regarding safety, electrical isolation and energy efficiency. The article gives an introduction to different architectures of battery management systems (BMS). There are different approaches to design a BMS the article describes in the first part. In the second part, there is a more precise description of the electronic hardware and the software behind a BMS. To understand both function and importance of a BMS, the article introduces in the third part a few applications of BMS in bigger battery packs.

Since August 2009, the first German offshore wind farm ‘alpha ventus’ is operating close to the wind measurement platform FINO1. Within the research project RAVE-OWEA the wind flow conditions in ‘alpha ventus’ were assessed in detail, simulated with a CFD wake model and compared with the measurements. Wind data measured at FINO1 have been evaluated for wind speed reduction and turbulence increase in the wake. Additionally operational data were evaluated for the farm efficiency. The atmospheric stability has been evaluated by temperature measurements of air and water and the impact of atmospheric stability on the wind conditions in the wake has been assessed. As an application of CFD models the generation of power matrices is introduced. Power matrices can be used for the continual monitoring of the single wind turbines in the wind farm. A power matrix based on CFD simulations has been created for ‘alpha ventus’ and tested against the measured data.

With the continued growth of renewable energy technologies, major changes are under way in a growing number of energy systems across the globe. Wind, solar, biomass, hydroelectric and geothermal solutions experience an impressive boom and have created a new business sector worth US$243 billion in 2011. This trend is not caused by recent breakthroughs in engineering; in fact most of the technology has been around for some time. The way we organize our energy infrastructure is not primarily a technical matter; it is above all a political decision. The scale-up of renewable energy supplies at the cost of today's fossil-fuel dominated energy infrastructure is a systemic transition from one technology regime to another and thus requires political leadership for setting the targets, guiding institutional change, freeing resources and deciding on the relevant regulations. Today's energy systems are based on well-established routines and – as any other existing societal arrangement – are governed by a certain degree of lock-in: because people are generally happy to do things the way they have done it in the past, they are unlikely to embrace change quickly. These “lock-ins” shape, to a large extent, the speed of change as well as the type of solutions required in order to leave behind what works for today in favor of what we want to work for tomorrow. This article provides an overview of recent developments in the energy systems in Germany, California and Japan. We show that in order to appreciate the dilemma's that arise when creating a more sustainable energy system, we need to understand the local political landscape and how it influences decision-making processes. Looking at the three regions, it becomes evident that the level of political leadership determines much of what technology can do to facilitate innovation in the field of sustainable energy.

On the path to an energy transition away from fossil fuels to sustainable sources, the European Union is for the moment keeping pace with the objectives of the Strategic Energy Technology-Plan. For this trend to continue after 2020, scientific breakthroughs must be achieved. One main objective is to produce solar fuels from solar energy and water in direct processes to accomplish the efficient storage of solar energy in a chemical form. This is a grand scientific challenge. One important approach to achieve this goal is Artificial Photosynthesis. The European Energy Research Alliance has launched the Joint Programme “Advanced Materials & Processes for Energy Applications” (AMPEA) to foster the role of basic science in Future Emerging Technologies. European researchers in artificial photosynthesis recently met at an AMPEA organized workshop to define common research strategies and milestones for the future. Through this work artificial photosynthesis became the first energy research sub-field to be organised into what is designated “an Application” within AMPEA. The ambition is to drive and accelerate solar fuels research into a powerful European field – in a shorter time and with a broader scope than possible for individual or national initiatives. Within AMPEA the Application Artificial Photosynthesis is inclusive and intended to bring together all European scientists in relevant fields. The goal is to set up a thorough and systematic programme of directed research, which by 2020 will have advanced to a point where commercially viable artificial photosynthetic devices will be under development in partnership with industry.

The continuous expansion of electricity generation from intermittent renewable energy sources (RES) is changing the present generation structure that has been designed to follow fluctuating demand considerably. In order to utilise a high share of supply-dependent RES, the future energy system needs to become more flexible than it is today. This paper describes the different flexibility options that can be implemented with regard to their major restrictions as well as their suitability to balance a certain deficit or surplus of RES generation. Furthermore, it outlines the importance of competition between these different balancing measures to meet the required level of flexibility at lowest cost.

In Germany more than 20% of the energy mix is made up of renewable energy and its share is rapidly increasing. The federal government expects renewables to account for 35% of Germany's electricity consumption by 2020, 50% by 2030 and 80% by 2050. According to the German Energy Agency, multi-billion euro investments in energy storage are expected by 2020 in order to reach these goals. The growth of this fluctuating energy supply has created demand for innovative storage options in Germany and it is accelerating the development of technologies in this field. Along with batteries and smart grids, hydrogen is expected to be one of the lead technologies. 2010 a commercialization roadmap for wind hydrogen was set up by the two northern federal states of Hamburg and Schleswig-Holstein with the goal of utilizing surplus wind power for the electrolytic production of hydrogen. With the creation of the “performing energy initiative”, 2011, Brandenburg and Lower Saxony joined this undertaking. The aim of this initiative is to set up demonstration projects in order to develop and optimize wind-hydrogen hybrid systems and prepare their commercialization for the time after 2020. Beside the conversion of hydrogen into electricity and fuel for cars, further markets like raw material for the chemical, petrochemical, metallurgy and food industry are going to be addressed. Considering the fact there are over 40 caves currently used for natural gas storage with a total volume of 23.5 billion cubic meters and 400 000 km gas grid available in Germany, the German Technical and Scientific Association for Gas and Water sees opportunities for hydrogen to be fed into the existing natural gas grid network. The name of this concept is power-to-gas. According to the current DVGW-Standards natural gas in Germany can contain up to 5% hydrogen. The GERG, European Group on the Gas Research sees potential to increase this amount up to 6% to 20%. Power-to-gas could serve both for fuel and for the storage of extra energy produced by renewable sources. The hydrogen produced via electrolysis could be drawn upon – directly or as synthetic natural gas (SNG) in a second additional methanation process step – to provide electricity by means of CCGT (combined cycle gas turbines) or CHP (combined heat and power) using for example fuel cells. It could also address the industrial and household heat market. DVGW is furthermore participating in the “Power-to-Gas Platform” that was set up in 2012 by the German Energy Agency, bringing together RnD institutes, renewable energy project developers and park operators, utilities, underground storage providers in order to create political support for this new technology. Demonstration projects will be completed by 2020 in order to develop business models (for storage, production and trade of “green gas”) and devices (electrolysers, turbines, smart gas metering, compressors, storage capacities amongst others) to enable the implementation of this concept on a broad scale. This means that a multitude of industrial players will be involved in the changes that will occur in the value chain: utilities (electricity, gas), power technology companies, car makers, heating device manufacturers, but also manufacturers of measurement, regulation and control devices, suppliers of the biogas and methanation industry. Germany is the pioneer in this field. This technology however increasingly interests its neighbours, with project developments in France, Italy, Spain, and UK but also in North America and North Africa. Germany can contribute its valuable experience (e.g. legal framework for power-to-gas) to the development of these industries. German participants in demonstration projects in these countries could for example be renewable energy park operators, RnD institutes and suppliers.

Indium, selenium, tellurium, gallium, molybdenum, cadmium and silicon are some of the major elements used in photovoltaic cells. Fully aware of the limited availability of these metals in future, recycling has been recognized as the most advisable end-of-life strategy to save these raw materials from turning into production wastes. On the other hand, statutory measures such as “Kreislaufwirtschaftsgesetz” (the German law encouraging closed-loop economy) aim to achieve a maximum quota of recycling and a minimum use of resources such as energy and raw materials. By the year of 2050, end-of-life photovoltaic panels are anticipated to amount to 9.57 million tons [1]. Although we are not there yet, discussions on recycling have already started. We have to prepare for higher waste volumes expected in the coming years. But already today we need to solve some environmental problems like loss of conventional resources (e.g., glass) and rare metals [2]. All of the known approaches for recycling photovoltaic semiconductor material seem economically and environmentally inefficient [3, 4]. In this paper, we report about reclaiming metals from scrap of thin film systems and associated photovoltaic manufacturing wastes like sandblasting dust and overspray. We also report one universal wet-chemical treatment for reclaiming the metals from CIS, CIGS or CdTe photovoltaic waste. Further, we discuss the application of our method to new PV systems, such as substrates other than glass (stainless steel, aluminum or plastic foil sheets) and alternative semiconductor alloys such as GaAs.