How To Increase Private Consumption

Transcription

1 ENERGY MANAGEMENT Many companies have been looking at the topic of energy management for a number of years, firstly to lower operating costs and secondly for ecological reasons. For companies with high energy consumption, energy management will even be politically encouraged in the future; the relevant standards are already in place. The European EN standard was finalised in 2009 and the international ISO standard, published in the middle of 2011, has set out the requirements for energy management systems. Energy management systems have been used by the industrial and commercial sectors for some time and are becoming increasingly popular in domestic households due to rising electricity costs and government regulations. Energy management systems are designed to optimise energy consumption Generally speaking, energy management can be seen as a way of optimising energy consumption (e.g. of heat, electricity, water) from an economic and ecological viewpoint. For example, turning down the heating at night and using water sparingly in households are two of the simplest forms of energy management. To implement a comprehensive energy management system, precise energy usage data must be obtained and analysed. Following on from this, various measures can then be implemented to ensure that energy is used more efficiently and energy costs are reduced. These processes are mostly handled by fully automatic systems that record and process data relating to the amount of energy used for heating, machinery, pumps, etc., and these systems often provide intelligent control of these consumers. Use in areas where savings can be made The higher the potential savings, the more worthwhile it is to implement energy management. For example, the energy costs associated with load management (avoiding peak loads by the controlled connection and disconnection of consumers) can sometimes be reduced enormously, particularly in the industrial sector. Energy management has been employed successfully in public buildings, department stores and office blocks, and is now gradually finding its way into domestic households. Now's the time for energy management in households Government measures in connection with renewable energies, particularly photovoltaics (PV), are making energy management an increasingly lucrative proposition for households. Between 2009 and 2012, the EEG (German Renewable Energies Act) promoted the private use of solar power by offering a special remuneration rate for private consumption, thus creating the necessary framework for implementing energy management in households. In the most recent amendment (dated ) to the EEG was cancelled due to high electricity procurement costs and a lower feed-in tariff. As a result, it is becoming increasingly lucrative for owners to consume the power themselves rather than feed it into the grid. Since June 2012, the feed-in tariff for domestic households in Germany has been ct/kwh. Instead of feeding all the PV power into the grid, it is now more financially attractive to use it in one's own home, and this attraction increases every time the cost of electricity rises. The following graph shows the benefit of increasing private consumption compared with feeding all the power into the grid: 07/2013 1/5

2 Assumptions: - Cost of electricity: 24 cents (net) - Rise in electricity cost: 4 % p.a. Example of a bill Financial return [ct/kwh] in 5 years assuming no private consumption (all the power fed into the grid): = feed-in tariff for 100% of the energy fed into the grid = 15 ct/kwh Financial return [ct/kwh] in 5 years assuming 30% private consumption: = feed-in tariff of 15 ct/kwh for 70% of the energy fed into the grid ct/kwh saving in electricity procurement costs through private consumption of 30% of the energy generated = 0.7 x 15 ct/kwh x 29.2 ct/kwh = 19,26 ct/kwh By increasing private consumption to just 30%, the financial return in just five years increases from 15 ct/kwh (when all the power is fed into the grid) to roughly 19.3 ct/kwh (rise in electricity cost: 4% p.a.). This represents a difference of nearly 30 per cent. After ten years, the difference is over 40 per cent. If 70% of the power generated by a PV system is used for private consumption, then this would currently produce a 95 per cent higher profit than if all the power were fed into the grid. As shown in the graph, the rate of private consumption, as well as electricity costs, plays a key role in maximising the profit. How high individual private consumption is essentially depends on two factors: firstly, consumer behaviour, i.e. the time at which most power is consumed in the household and, secondly, the relationship between the size of the PV system and annual electricity consumption. Small systems (where system yield < electricity consumption) have higher levels of private consumption than larger systems. In a typical four-person household in which the annual electricity consumption is more or less equal to the system yield, the average private consumption figure will be in the region of 20% - 40%. To increase the amount of private consumption, it is important to adapt the consumption of electrical energy to the level of irradiation whenever possible for example, through the use of energy management. The easiest way to do this is to control domestic appliances manually. In the past, the technical and organisational prerequisites for the efficient implementation of energy management in households have often been lacking, but a significant change is now in the air. 07/2013 2/5

3 Prerequisites for efficient energy management The intelligent meter, known as a "Smart Meter", is considered to be an important cornerstone of energy management and is used to record and process energy generation and consumption data. Even though not widespread at present, every household could be fitted with a digital meter in the future. Their use permits the introduction onto the electricity market of variable prices, which are under increasing discussion, and which would create another incentive for implementing intelligent energy management in households. When electricity tariffs are low, as many consumers as possible should be operating; when they are high, the energy management system switches off the appliances that are not required. Further requirements include intelligent end devices that can be controlled via suitable interfaces. A sophisticated energy management system, different versions of which should be available, is also important. Energy management systems already available for households Systems, often referred to as Home Management systems, usually control consumers via switchable wireless power sockets. However, the cost-effectiveness of these already available devices should be analysed very carefully. Although many of the devices on the market can indeed reduce energy consumption and costs, the investment costs often bear little relationship to the benefit. Simple, low-cost solutions, such as timers for circulating pumps, or system-integrated solutions, for instance inverter-integrated energy management relays for controlling consumers, will probably be the most successful at present. Full benefits of energy management only obtained using storage batteries To obtain the full benefit of the energy management system, energy storage batteries will in future assume a key role. With renewable energies, volatile energy yields will mean that the energy generated will rarely satisfy the demand. Analyses based on actual system and consumption data, including several independent studies, show that the average private consumption of a household, the energy requirements of which are more or less covered by the yield of the PV system, is around 30%. The amount of energy used for private consumption can be increased to over 60% by using batteries for short-term energy storage when transferring energy from day to night. The following graph shows the relationship between private consumption rate and storage capacity of an average four-person household with an annual electricity consumption of 5000 kwh. 07/2013 3/5

4 Like the now frequently used thermal storage systems, electric storage systems are used to provide energy when it is needed. Private consumption can therefore be maximised and the amount of electricity purchased from the utility company kept to a minimum. At present, however, no economic benefit can be gained from using photovoltaic systems and storage batteries due to the high price of the batteries. The vision energy autonomy with long-term storage A further step must be taken if we are to increase private consumption from the predicted 60 % to close to 100%. Short-term storage batteries can be used to balance the energy difference between day and night, but not between the winter and summer months. By using a long-term storage mechanism, such as hydrogen, energy autonomy will become a reality for households. Surplus energy generated in the summer can be stored as hydrogen via electrolysis and converted back into electricity using a fuel cell during the winter when irradiation levels are lower. For PV system operators, the public grid then only acts as a back-up; nothing stands in the way of energy self-sufficiency. Future outlook and summary Variable electricity tariffs, continually rising electricity costs and falling prices for PV systems and storage make private consumption even more attractive, and will result in energy management eventually finding its way into domestic households without any further political encouragement. Even though there are currently no economic benefits to be gained, it is highly likely that high private consumption rates and lower energy costs can be achieved in the future by using intelligent energy management systems with storage batteries. In the foreseeable future, increasing the number of private solar power and long-term storage systems will make it possible to provide a virtually autonomous supply of energy. How quickly this vision will become reality depends on the political climate, increases in electricity prices, which are difficult to predict, and above all the cost of photovoltaic systems and storage. Characters (no spaces): 8,723 Words: 1,591 Franz Breitwieser, System Technology, Fronius International GmbH. Photographs: Fronius International GmbH, reproduction free of charge. About Fronius International GmbH Fronius International is an Austrian company with headquarters in Pettenbach and other sites in Wels, Thalheim and Sattledt. With 3,250 employees worldwide, the company is active in the fields of battery charging systems, welding technology and solar electronics. Around 95% of its products are exported through 17 international Fronius subsidiaries and sales partners/representatives in over 60 countries. In financial year 2010, the company generated a total turnover of 499 million euros. With its outstanding products and services and 737 active patents, Fronius is world technology leader. 392 employees work in research and development. 07/2013 4/5

5 Enquiries: Author: Ing. Franz Breitwieser, 43 (664) , Froniusplatz 1, 4600 Wels, Austria. Trade press: Mag. Andrea Schartner, , Froniusplatz 1, 4600 Wels, Austria. 07/2013 5/5