Energy Saving Technologies

Introduction

The course is developed within the frames of project “Development of Training Network for Improving Education in Energy Efficiency” acronym: ENERGY, grant Nr. 530379-TEMPUS-1-2012-1-LVTEMPUS-JPCR.Project was approved by the European Commission in frame of program Tempus IV – Fifth call for proposals (Programme guide EACEA/25/2011).Sub-programme: Joint ProjectsAction: Curricular ReformDeliverable: 2.1 Development and translation of study courses within the frame of direction enhancement of energy efficiency (EEE).

This project has been funded with support from the European Commission Project. This publication reflects the views only of the author, and the Commission cannot be held responsible for any use, which may be made of the information contained therein.

Code

Course title Energy Saving Technologies

Course status in the program Courses of Free Choice

Course level Undergraduate Studies

Course type Academic

Field of study Power and Electrical Engineering

Responsible instructor Anastasia Zhiravetska

Academic staff Anastasia ZhiraveckaNadezhda KunicinaAnatolijs ZabaštaAnsis Avotins

Volume of the course: parts and credits points

1 part, 2.0 Credit Points, 3.0 ECTS credits

RTU Course "Energy Saving Technologies"

Theme Hours

Introductive class 2

Co-generation 2

Smart metering 4

Distributed generation 2

DC transmission lines 4

Approaches to reduction of electric energy losses 4

Electrical motors and drives 6

Effective lighting 2

Supercapacitors 2

Standartization and legal bases 4

Course outline

Study subject structure

Part Semester CP ECTS Exam Lectures

Practical

Lab.

1. Autumn 2.0 3.0 * 2.0 0.0 0.0

Smart cities and regions:overview of energy saving technologies

Smart concepts • The smart region concept is

important topic as for building and constriction sector as well for electrical engineering sectors;

• The different technological solutions and best practice is available on the market;

• The mutual recognition of the best practice solutions and application of the best ideas in the practice will improve an innovative tendency.

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Research Executive Agency (REA) building concept, Brussels

The technological concept of self – sustainable region

The technological concept of new energy generation of self – sustainable region foreseen integration of small energy amount production on sites, concept called smart grids. The following attributes would need to be addressed in smart grids:

• Absolute reliability of supply and optimal use of power generation and storage;• Minimal environmental impact of electricity production and delivery;• Reduction in electricity used in the generation of electricity and an increase in

the efficiency of the power delivery system and effectiveness of end uses;• Resiliency of supply and delivery from physical and cyber attacks and major

natural phenomena (e.g., hurricanes, earthquakes, tsunamis, etc.);• Assuring optimal power quality for all consumers who require it;• Monitoring of all critical components of the system and outage prevention.

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Directive 2012/27/EU on energy efficiency

The latest adoption of the legal base in several levels gives clear guidelines what should be done in the Sustainable energy area.

The main is Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency called Directive 2012/27/EU

The clear targets for Public building renovations sets a 3% annual renovation target for public buildings owned and occupied by its central government from the beginning of 2014 onwards.

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Key requirements of Directive 2012/27/EU for public buildings

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Directive 2012/27/EU basic requirements (1)

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• A 3% renovation requirement for buildings owned and occupied by central governments from 1 January 2014; the 3% rate shall be calculated on the total useful floor area of buildings that are over 250m2 (the scope is limited to 500m2 until 9 July 2015);

• Renovation of central government buildings to meet at least the national minimum energy performance EPBD requirements;

• The establishment of an inventory of central government buildings that will include energy performance and any other relevant energy data;

• Alternatively, taking measures in central government buildings, including deep renovations and behavioural changes, to achieve an equivalent amount of savings to the 3% approach, with a milestone in 2020 for verifying this equivalence;

• Addressing the buildings with the worst energy performance first;

Directive 2012/27/EU basic requirements (2)

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• Consideration of the building as a whole when doing a comprehensive renovation (envelope, equipment, operation, etc.).

• EED lays down only minimum provisions for energy savings measures and does not prevent member states of European Union (MSs) from introducing more stringent requirements.

• MSs can use the buildings covered by the provisions of Article 5 to demonstrate the economic, environmental and social co-benefits of deep renovations, while also trailblazing the renovation of all buildings to nearly zero energy levels. This is especially relevant given that under the Energy Performance of Buildings Directive (2010/31/EU) [6], MSs have to increase the numbers of such buildings.

• The energy performance level of the renovated building should be brought as close as possible to requirements for newly built or nearly-zero energy buildings.

Criteria for an ambitious and successful implementation

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The twenty most important criteria for an ambitious and successful implementation of the Energy Efficiency Directive, which means achieving the EU 2020 target and paving the way for improving energy efficiency beyond that date consist also recommendations according to the national requirements and it’s target.

• National building renovation strategies are in place and aim at an 80% energy consumption reduction target for the country's entire building stock, to be achieved through the gradual and systemic improvement of the energy performance of all buildings by 2050.

• The multiple benefits arising from deep renovations are integrated into a policy framework to stimulate deep renovation (including staged deep renovations) of the building stock.

Efficient Electric End-use Technology Alternatives

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EU’s energy strategies by 2050

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• To reach the long-term decarbonisation goals, the EU Roadmap for moving to a competitive low carbon economy in 2050 identified the need of reducing carbon emissions in residential and services sectors by 88-91% by 2050 compared to 1990 levels.

• In addition, the Energy Roadmap 2050 concludes that ‘higher energy efficiency potential in new and existing buildings is key’ in reaching a sustainable energy future in the EU, contributing significantly to the reduction of energy demand, the security of energy supply and the increase of competitiveness.

• Furthermore, the Roadmap for a Resource Efficient Europe identified buildings among the three key sectors responsible for 70-80% of all environmental impacts. Therefore, better construction and use of buildings in the EU would influence 42% of the final energy consumption, about 35% of the carbon emissions, more than 50% of all extracted materials and could save up to 30% of water consumption.

Source: Building performance institute Europe Boosting Building Renovation: an overview of good practices

Retrofitting requirements Germany (1)

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• The National requirements in different countries are different, not all requirements are standardised in EU level. For example in Germany, like in other EU countries, there are requirements regarding the energy performance of buildings undergoing major renovation. Germany has ambitious targets for the overall energy performance of the building stock.

• The German Federal Government's target for 2050 is to have a building stock that is almost climate-neutral. To achieve this target, the heating requirement is to be reduced by 20% by 2020, with primary energy demand dropping by 80% by 2050. The annual refurbishment rate is to be increased from 1% to 2% by 2020.

• To establish a long-term refurbishment strategy with reliable framework conditions, the Energy Concept (“Energiewende”) foresees the compilation of a refurbishment roadmap for Germany's total building stock covering the period 2020-2050.

• For the renovation of buildings, the German building regulation (EnEV) sets component-specific minimum efficiency requirements which have to be implemented when changing or modernising a building components.

Retrofitting requirements Germany (2)

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• As an alternative to complying with individual requirements for structural elements, a holistic assessment can also be made –analogous to the calculations for new buildings. The requirements are met if modified residential or non-residential buildings exceed the relevant requirements for similar new buildings by no more than 40%.

• In the case of single measures, modifications are to be designed in such a way that specific heat transfer coefficients of the exterior components are not exceeded.

• Apart from the conditional requirements which result from refurbishment or replacement of a structural element, the Energy Saving Ordinance also contains retrofitting obligations which must be fulfilled by the building owners within a specific time frame. All retrofitting obligations are also subject to the precondition for cost-effectiveness. According to legal requirements, these are measures with short-payback periods.

German retrofitting cost-effective obligations (1)

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• Insulation requirement of hot water pipes: it exists since 2004 and requires the insulation of all previously non-insulated and accessible hot water distribution pipes and fittings in unheated rooms.

• Insulation requirement of top floor ceilings: from December 31, 2011, the obligation applies to all top floor ceilings, above which there is either walkable or non-walkable space. Moreover, the obligation also applies to top floor ceilings, above which there is an attic. As an alternative, the roof located above can be insulated instead of the top floor ceiling. However, there is no control/compliance mechanism for this requirement; it is used by the industry as an incentive to promote ceiling insulation.

• Retrofit of HVAC systems: retrofitting automatically operating control devices with separate reference values for the room humidity is mandatory for larger air conditioning and ventilation systems, insofar as these systems are intended to affect the humidity of the indoor air.

German retrofitting cost-effective obligations (2)

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• Replacement of electrical heat storage systems: electrical heat storage systems must be gradually taken out of operation, if the heating of the building is provided exclusively by electrical heat storage systems. This applies to larger residential and non-residential buildings, Germany has adopted financial measures and mechanisms to support building retrofit, such as the successful “KfW Energy-efficient Refurbishment programme” (former KfW CO2 Building Rehabilitation Programme).

• The programme is intended to promote measures for saving energy and reducing CO2 emissions in residential buildings by financing corresponding measures, both at low interest rates and in the long-term. A refurbished building which requires, for instance, 115% of the primary energy of a comparable new building- (therefore only 15% more)- is assigned to the promotion standard “KfW efficient building 115” and receives a 2.5% credit and subsidy, while a “KfW efficient building 55” (i.e. 55% of the comparable new building) receives a much higher subsidy of 12.5%.

European joint initiative on Smart Cities and Communities

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• In general Smart Cities and Communities annual joint research initiatives brings together cities, industry and citizens to improve urban life through more sustainable integrated solutions. This includes applied innovation, better planning, a more participatory approach, higher energy efficiency, better transport solutions, intelligent use of Information and Communication Technologies (ICT), etc.

• From other hand smart cities call defines the targets according to which smart cities implementation concept will be measured.

Impacts of the EU Smart Cities and Communities initiatives

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• deploy wide-scale, innovative replicable and integrated solutions in the energy, transport, and ICT;

• trigger large scale economic investments with the repayment of implementation costs in acceptable time lines (to facilitate the bankability of the projects);

• increase the energy efficiency of districts and of cities and foster the use of renewables and their integration energy system and enable active participation of consumers;

• increase mobility efficiency with lower emissions of pollutants and CO2;

• reduce the energy costs;• decarbonise the energy system while making it more secure and stable;• create stronger links between cities in EU Member States with various

geographical and economical positions through active cooperation.

Technologies capable of improving energy efficiency

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• Many technologies capable of improving energy efficiency exist today. Some have been established for several decades (e.g., fluorescent lamps), others are new to the market-place (e.g., white LED task lighting), still others have been available for a while, but could still benefit from increased penetration (e.g., lighting controls).

• The majority of the technologies listed consume less energy than conventional alternatives. Some of the technologies listed are electrotechnology alternatives to thermal equipment.

• In many cases they are more energy efficient than conventional thermal alternatives. One of the primary advantages of electrotechnologies is that they avoid on-site emissions of pollutants.

• The buildings technologies are broken down into categories of building shell, cooling, heating, cooling and heating, lighting, water heating, appliances, and general. The industry technologies are divided into the end-use areas of motors, boilers, process heating, waste treatment, air and water treatment, electrolysis, membrane separation, food and agriculture, and general.

EU funded initiatives

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District of the Future (DOF): 608649 is ongoing research project from 2013-11-01 to 2016-10-31]. Project was supported under FP7-SMARTCITIES-2013 call. The project contributes to the adoption of green ICT technologies by city authorities. Just by reapplying the DoF approach in other European city districts the project will to make a sustainable contribution to the objectives of EC 2020 Energy and Climate Change, 20% of energy from renewable, 20% increase of energy efficiency, 20% reduction of greenhouse gas emissions in comparison with 1990.

Lighting

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Artificial illumination is essential to society. Artificial lighting is now ubiquitous to nearly every aspect of our life. In the U.S., lighting systems currently account for about one-tenth of total electricity consumption in residential buildings, nearly one quarter of total electricity consumption in commercial buildings, and 6 TO 7% of total electricity consumption in manufacturing facilities. Worldwide, artificial illumination is estimated to demand 20 to 25% of all electric energy in developed countries.

Energy Labeling Directive 2010/30/EU

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• Energy Labeling Directive defines the legal framework for setting ecodesign requirements on energy-related products, including lighting products. Ecodesign requirements are minimum requirements that the products need to fulfill if they are to display the CE marking, which is a condition for their placing on the EU market. The original directive from 2005 covered only energy-using products, its scope was extended to energy-related products in 2009.

• Directive 2009/125/EC of the European Parliament and of the Council of 21 October 2009 establishing a framework for the setting of ecodesign requirements for energy-related products.

• This is the piece of legislation that covers incandescent lamps and their more energy efficient alternatives.

Space conditioning

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• The primary purposes of space conditioning are to heat, cool, dehumidify, humidify, and provide air mixing and ventilating.

• To this end, electricity drives devices such as fans, air conditioners, chillers, cooling towers, pumps, humidifiers, dehumidifiers, resistance heaters, heat pumps, electric boilers, and various controls used to operate space-conditioning equipment. Because of its significance and large impact on electricity use across the residential, commercial and industrial sectors, innovations in technologies related to space conditioning may have a substantial effect on how electricity is used in the future.

Innovative Space Conditioning Technologies

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Domestic Water Heating

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• Domestic water heating is essential for the comfort and wellbeing of peoples. Hot water is used for a variety of daily functions, including bathing, laundry and dishwashing. Water heating is also a significant end user of electricity, particularly for the residential sector.

• Indeed, water heating accounted for 9.1% of residential electricity use in 2001. It makes up a smaller share in the commercial sector, consuming 1.2% of commercial electricity use in 1999. Electricity is used to run electric resistance water heaters, heat pump water heaters, pumps and emerging devices such as microwave water heaters. Because of the importance of water heating to society—in terms of both functionality and electricity use—maximizing the contributions by water heating technologies see table 4 to a perfect electric energy service system should be a focus of future innovation.

Innovative Domestic Water HeatingTechnologies

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Ductless Residential Heat Pumps and Air Conditioners

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• Approximately 28% of residential electric energy use can be attributed to space conditioning in US. Use of variable frequency drive air conditioning systems can offer a substantial improvement when compared to conventional systems.

• In addition, in many climate zones, the industry has long recognized that the application of electric-driven heat pump technology would offer far greater energy effectiveness than fossil fuel applications.

• However, except in warmer climates, the cost and performance of today’s technology in insufficient to realize that promise. These ductless systems have the potential to substantially change the cost and performance profile of heat pumps in the U.S.

Variable Refrigerant Flow Air Conditionings (1)

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• Ducted air conditioning systems with fixed-speed motors have been the most popular system for climate control in multi-zone commercial building applications in North America. These systems require significant electricity to operate and offer no opportunity to manage peak demand.

• Multi-split heat pumps have evolved from a technology suitable for residential and light commercial buildings to variable refrigerant flow (VRF) systems that can provide efficient space conditioning for large commercial buildings. VRF systems are enhanced versions of ductless multi-split systems, permitting more indoor units to be connected to each outdoor unit and providing additional features such as simultaneous heating and cooling and heat recovery. VRF systems are very popular in Asia and Europe and, with an increasing support available from major U.S. and Asian manufacturers, are worth considering for multi-zone commercial building applications in the U.S.

Variable Refrigerant Flow Air Conditionings (2)

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• VRF technology uses smart integrated controls, variable-speed drives, refrigerant piping and heat recovery to provide products with attributes that include high energy efficiency, flexible operation, ease of installation, low noise, zone control and comfort using all-electricity technology.

• Ductless space conditioning products, the forerunner of multisplit and VRF systems, were first introduced to Japan and elsewhere in the 1950s as split systems with single indoor units and outdoor units. These ductless products were designed as quieter, more efficient alternatives to window units.

Heat Pump Water Heating (1)

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• Heat pump water heaters (HPWHs) based on current Japanese technology are three times more efficient than electric resistance water heaters and have the potential to deliver nearly five times the amount of hot water, even compared to a resistance water heater.

• HPWHs are significantly more energy efficient than electric resistance water heaters, and can result in lower annual water heating bills for the consumer, as well as reductions in greenhouse gas emissions.

• Heat pump costs limited their use. Water heating constitutes a substantial portion of residential energy consumption. In 1999, 120,682 GWh of electricity and 1,456 trillion Btu of natural gas were consumed to heat water in residences, amounting to 10% of residential electricity consumption and 30% of residential natural gas consumption. While both natural gas and electricity are used to heat water, the favorable economics of natural gas water heaters have historically made them more popular than electric water heaters.

Heat Pump Water Heating (2)

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• Heat pump water heaters, which use electricity to power a vaporcompression cycle to draw heat from the surrounding environment, can heat water more efficiently for the end user than conventional water heaters (both natural gas and resistant element electric). Such devices offer consumers a more cost-effective and energy-efficient method of electrically heating water. The potential savings in terms of carbon emissions at the power plant are also significant. Replacing 1.5 million electric resistance heaters with heap pump water heaters would reduce carbon emissions by an amount roughly equivalent to the annual carbon emissions produced by a 250 MW coal power plant.

• Heat pump water heaters have been commercially available since the early 1980s and have made some inroads in some places in the world, particularly in Europe and Japan.

Motors and Drives (1)

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• Electric motors and drives use about 55% of all electricity in the U.S. In addition, electrically driven equipment accounts for about 67% of industrial electricity use in the U.S. As a result of their prevalence, the efficient use of motors and drives presents a considerable opportunity for energy savings in the industrial sector and beyond. Applications of electric drives include compressors, refrigeration systems, fans, blowers, pumps, conveyors, and assorted equipment for crushing, grinding, stamping, trimming, mixing, cutting and milling operations.

• It is best to focus on the entire drive system to realize maximum energy savings. A drive system includes the following components: electrical supply, electric drive, control packages, motor, couplers, belts, chains, gear drives and bearings. In general, efficiency improvements can be made in four main categories: the prime mover (motor), drive controls, drive train, and electrical supply.

Motors and Drives (2)

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• Indirect energy savings can also be realized through efficient motor and drive operation. For example, less waste heat is generated by an efficient system, and therefore, a smaller cooling load would result for an environment that is air conditioned. The efficiency opportunities in the operation and maintenance of electric drive systems, equipment retrofit and replacement, and controls and alterations to fans, blowers, and pumps.

• The efficiency of motors and drives can be improved to some extent by better operation and maintenance practices. Operation and maintenance measures are typically inexpensive and easy to implement, and provide an opportunity for almost immediate energy savings.

Electrical Supply

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• Operation at rated voltage: Motors are most efficient if they are operated at their rated voltage.

• Phase balance: Balance three phase power supplies.

• Efficient power systems: Losses can occur in the power systems that supply electricity to the motors. Check substations, transformers, switching gear, distribution systems, feeders and panels for efficient operation. De-energize excess transformer capacity.

Cogeneration or combined cooling and heating

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In a CCHP system the thermal or electrical/mechanical energy is further utilized to provide space or process cooling. The CCHP systems are known also as trigeneration systems and as building cooling heating and power (BCHP) systems. One can say that a cogeneration system is a CCHP system without any thermally activated equipment for generating cooling power.

The CCHP systems are classified into two categories:

• traditional large-scale CCHP systems (predominantly CHP systems without cooling options) in centralized power plants or large industries;

• relatively small capacity distributed CCHP units with advanced prime mover and thermally activated equipment to meet multiple energy demands in commercial, institutional, residential and small industrial sectors.

Cogeneration or combined cooling and heating systems classification

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The distributed CCHP systems are classified in accordance with their capacity as follows:

• micro systems (capacity under 20 kW);

• mini systems (capacity under 500kW);

• small scale systems (capacity under 1MW);

• medium scale systems (capacity from 1 to 10MW);

• large-scale systems (capacity above 10MW).

Advantages of combined cooling and heating systems

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A typical CCHP system comprises the prime mover, electricity generator, heat recovery system and thermally activated equipment. The waste heat from the engine is used to heat up the domestic water, to generate heating power during the winter and to drive the adsorption chiller (for cooling power) during the summer.

The main advantages of distributed CCHP systems are: high fuel energy utilization; low emission; increased reliability of the energy supply network.

The prime mover selected to meet diverse demands and limitations can be steam turbines, reciprocating internal combustion engines, combustion turbines, microturbines, Stirling engines and fuel cells. The thermally activated systems include absorption chillers, adsorption chillers and desiccant dehumidifiers.

A comparative presentation of main cogeneration systems is shown in the schematic diagram of a micro combined cooling, heating and power system.

Diagram of a micro combined cooling, heating and power system

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Adsorption chiller

Natural gas Gas engine cogeneration unit

Cooling tower

Heat exchanger Hot water

storage tank

Colector pipe

Supply water

Domestic hot water

Colector pipe

Space heating/cooling

Electricity

Cold water

storage tank

Cooling tower

Heat exchanger

Equipment Retrofit (1)

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Equipment retrofit and replacement measures require more money and time to implement than do operation and maintenance measures; however, they can also result in more significant energy savings.

• Heat recovery: Modify equipment to recover heat. The waste heat can supply heat for another part of the process, reducing the demand on heating equipment.

• Controls for scheduling: Install controls to schedule equipment.

• Turn off motors when they are not in use, and schedule large motors to operate during off-peak hours.

• Other controls: Consider power factor controllers in low-dutyfactor applications, and feedback control systems.

• Variable speed drives (adjustable speed drives): Install variable speed drives to control the shaft speed of the motor. This reduces energy consumption considerably by matching the motor speed to the process requirements.

Equipment Retrofit (2)

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• Replacement of throttling valve with variable-speed drive: Control shaft speed with a variable-speed drive instead of a throttling valve. Throttling valves are associated with significant energy losses.

• Replacement of pneumatic drives: Consider replacing pneumatic drives with electric motors, if possible. Pneumatic drives use electricity to generate compressed air which then is converted to mechanical energy. Electric motors are much more efficient; but in some applications, pneumatic drives are preferred because of electrical hazards or because of the need for lightweight and high power drives. The main inefficiency of pneumatic drives arises from air leaks, which are hard to eliminate or avoid.

• Replacement of steam jets: Replace steam jets on vacuum systems with electric motor-driven vacuum pumps.

• High-efficiency motors: Install high-efficiency motors in all new designs and system retrofits, and when motors need replacement.

Process Heating

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• Process heat accounts for 10% of industrial end-use of electricity. Although this percentage is small compared to electric drive systems, it is significant enough that energy efficiency improvements in process heat applications have the potential for a substantial impact on overall electrical efficiency. The four main ways for process heat to be generated are with combustible fuel-based systems, electric-based systems, thermal recovery systems, or with solar collection systems.

• When all types of process heat are considered, electrically powered systems only account for a few percent of the total. The share of electric process heat systems is likely to increase in the future because of several advantages associated with electric systems, including ease of control, cleanliness at the point of use, safety, small size, and applicability for a large range of capacities.

• The most common electric process heat technologies include resistance heaters, induction heaters, infrared systems, dielectric systems (RF and microwave), electric salt bath furnaces, and direct arc electric furnaces.

Electricity and heat production

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According to the Directive 2004/8/EC [12] on the promotion of cogeneration based on a useful heat demand in the internal energy market cogeneration means the simultaneous generation in one process of thermal energy and electrical and/or mechanical energy. In literature the following definitions are often used:

• Cogeneration is the combined production of electrical (or mechanical) and useful thermal energy from the same primary energy source;

• Cogeneration is the sequential production of thermal and electric energy from a single fuel source;

• Cogeneration is on-site generation and utilisation of energy in different forms simultaneously by utilising fuel energy at optimum efficiency in a cost-effective and environmentally responsible way. The mechanical energy produced by cogeneration can be used to drive auxiliary equipment as well. The thermal energy can be used either for heating or for cooling. Cooling can be obtained by thermally driven chillers (usually adsorption or absorption chillers).

The advantages of cogeneration in electricity and heat production

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In a in power plant, large amount of heat (50-70%) is wasted with exhaust gases and cooling agent. A large portion of the waste heat can be recovered and used by combining the electrical generation and heat production processes, increasing in this way the overall efficiency to 80-90%. This combination of the electrical generation and heat production processes represents the combined heat and power (CHP) generation or cogeneration concept.

The main advantages of cogeneration systems are the following:

• improve energy efficiency at national level leading to conservation of fossil energy resources;

• enable locally generation of electricity and reduce the heat losses;

• enable the use of different fuels;

• can be used in remote areas;

• reduce the environmental impact due to higher efficiency of fuel conversion.

Comparison between individual generation of electricity and heat v/s cogeneration

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Thermal power plant

Fuel100%

Electricity40%

Energy loss60%

Boiler

Fuel100%

Heat85%

Energy loss15%

Cogeneration plant

Fuel100%

Electricity40%

Energy loss10%

Heat50%

a) b)

generation of electricity

cogeneration

generation of heat

The main disadvantages of cogeneration systems

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• have high investment and operation costs;

• require utilisation of the generated heat in the case the generated electricity is fully utilised;

• require back-up system in order to ensure supply security of electricity and heat, increasing the investment cost.

The main components of a cogeneration system

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• a prime mover;

• an electrical generator;

• a heat recovery exchanger;

• operating control systems

Prime mover

Fuel

Electricity

Generator

Heat

Heat recuperator

Exhaust gases, cooling water

Cogeneration technology in electricity and heat production (1)

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The prime mover is a thermal engine (Rankine, Brayton, Diesel, Otto, Stirling) or a combination of thermal engines which converts chemical energy of fuel into mechanical energy transmitted to electrical generator. A special system, which converts fuel chemical energy directly into electricity, is the system that uses fuel cell as prime mover. The heat recover see maybe a heat exchanger or a network of heat exchangers which transfers the heat from exhaust gases or engine cooling agent to the heating agent or to water (domestic hot water).

The most important indices used to compare different cogeneration systems are the following:

mechanical efficiency of prime mover (heat engine):

where: is mechanical power of prime mover;

is heat flow produced by fuel combustion;

is fuel mass flow rate, kg/s or Nm3/s;

Cogeneration technology in electricity and heat production (2)

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LHV is lower heating value (net calorific value) of fuel, kJ/kg or kJ/Nm3.

electrical efficiency:

where: is electrical power generated by system (electrical power output);

thermal efficiency:

where is the heat flow rate generated by the system.

Cogeneration technology in electricity and heat production (3)

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overall efficiency or total energy efficiency:

This equation is a subject of discussions because it is not appropriate to add heat with electricity since the heat quality is lower than that of electricity. It is very difficult to obtain 1 kW electric from 1 kW thermal due to the losses of heat conversion into electricity. We can use another index that uses the exergy, as a measure of energy quality, of system input and output, instead of the overall efficiency.

Cogeneration technology in electricity and heat production (4)

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Exergetic efficiency:

Where is exergy flow rate of generated heat;

is exergy flow rate associated to fuel:

ef is specific exergy of fuel, kJ/kg or kJ/Nm3.

Cogeneration technology in electricity and heat production (5)

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power to heat ratio:

fuel energy savings ratio:

where

is fuel power input in individual generation system of heat ( )

or electricity ( );

is fuel power input in the system that cogenerates the same amount of heat ( ) and electricity ( ).

Cogeneration technology in electricity and heat production (6)

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The gas turbine can operate in a simple Brayton (called Joule cycle when irreversibilities are ignored) thermodynamic cycle or in a combined Brayton-Rankine cycle. The gas turbine systems have been developed initially for industrial and utility applications and as aircraft engines. Later, these turbines have been modified in order to be used in stationary applications. The modified turbines are called aeroderivative turbines. The main advantages of gas turbine cogeneration systems are the following: low capital cost; low-cost maintenance; low installation cost; fast start-ups; rapid response to changing load; fuel-switching capabilities, high efficiency of larger plants; high temperature level of heat (450-600°C) which can be recovered; good environmental performance. The main disadvantage is in low heat to power conversion efficiency. Due to their advantages, the gas turbine systems are the most frequently used technology in cogeneration systems. Their electric power output ranges from few kilowatts (micro turbine systems) to 250 MW.

Biogas production from waste

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Gas production and management of both the power unit and power supply is well designed and allows to born unused methane in order to reduce CO2 emissions in the Riga region.

Biogas production process monitoring

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Six gas engines JENBACHER JGS 320 GS- B.L –B21 (Austria) with the following parameters each: input power 2620 kW, power production 1048 kW, potential heat production 1229 kW, power production factor 40%, heat production factor 46.9%, net efficiency 86.9%, gas consumption 524 m3 /h (CH4= 50 %)

Thermal Energy Storage

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Thermal energy storage (TES) can also be considered an industrial energy source. TES is the storage of thermal energy in a medium (i.e., steam, water, oil or solids) for use at a future time. TES is used to manage energy in several ways. For example, TES provides peak load coverage for variable electricity or heat demands, it allows for the equalization of heat supplied from batch processes, and it enables the storage of energy produced during off-peak periods for use during peak periods. TES is also used to decouple the generation of electricity and heat in cogeneration systems. Better energy management through the use of TES can help industries reduce their dependency on utilities for energy supply. In addition, TES systems can provide a backup reserve of energy in the event of a power outage.

Industrial Energy Management Programs

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The establishment of an energy management program is a crucial part of the process of setting and achieving industrial energy-efficiency goals.

First and foremost, the establishment of an energy management program requires a commitment from management to initiate and support such a program.

Once management is committed, an energy management program should be custom designed for each specific application, since efficiency goals vary with the type and size of the industry. However, there are several main guidelines that are applicable to any energy management program.

Six main steps of Industrial Energy Management

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• Appoint energy managers and steering committee

• Gather and review historical energy use data

• Conduct energy audits

• Identify energy-efficiency opportunities

• Implement cost-effective changes

• Monitor the results

This general procedure may be applied to any type of facility, including

educational institutions, commercial buildings, and industrial plants.

Smart meters

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• A smart meter is usually an electrical meter recording the consumption of electric energy in intervals of an hour or less and at least daily exchanging with this information back to the utility for monitoring and billing purposes.

• Smart meters enable two-way communication between the meter and the central system.

• Unlike home energy monitors, smart meters can gather data for remote reporting. Such an advanced metering infrastructure (AMI) differs from traditional automatic meter reading (AMR) in that it enables two-way communications with the meter.

Difference between the conventional and the smart meter data process

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Smart meters as a challenge

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• The metering company faces the challenge of initially replacing old meters by smart meters.

• Installation of smart meters requires another type of operation for data collection and data exchange. As smart meters introduce a high amount of frequent data flows, processes and systems to be adapted and prepared accordingly.

• The data collection process will not depend on clients being at home but will be a continuous, automated process, which should simplify daily operation of the metering company. Benefits can be explained by looking at the differences between the current situation with the old meter and the future situation with the new meter, as shown before.

Smart houses (1)

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• One of such load management is smart house concept. Smart houses became popular during the last year, because of their intelligent energy-saving methods. The idea behind a smart house is to build an internal network in the house from which everything can be monitored and controlled over a common server. In such a way it is possible to watch the energy prices and using energy intensive devices like washing machines over night when the prices are at their lowest.

• In a schematic way, a smart home can be described by a house which is equipped with smart objects, a home networks make it possible to transport information between objects and a residential gateway to connect the smart home to the outside Internet world. Smart objects make it possible to interact with inhabitants or to observe them.

Smart houses (2)

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• Those smart objects can be just a light that we can control or ask it about its state, a refrigerator which knows its state and is able to supply in line by itself, telephony, security systems, videos on demand etc. All those objects will be connected to the home network to inform on their states or receive instructions.

• Home networking allows the home to become fully connected, controlled externally as well as internally.

• The residential gateway offers an extern access by the way of Ethernet or Internet network. This gateway makes it possible to the house to connect new services and to download them. The service provider is in charge of the new services for inhabitants and their accessibility.

System block diagram Smart home

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References

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1. Anastasija Zhiravecka, Nadezhda Kunicina edt. Energy Saving Technologies, Riga, Latvia 266 p. 2014 (in press)

2. Li, Xianguo (Ed.) Green Energy. Basic Concepts and Fundamentals. Series: Progress in Green Energy, Vol. 1. 2011, XVI, 288 p.

3. Clark W. Gellings The Smart Grid: Enabling Energy Efficiency and Demand Response by Lilburn, GA: Fairmont Press: Taylor & Francis distribution, 300 p.

4. Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency

5. Public building renovations http://eedguidebook.energycoalition.eu/public-renovation.html

6. Energy Performance of Buildings Directive (2010/31/EU)

7. Building performance institute Europe Boosting Building Renovation: an overview of good practices 63.p. http://bpie.eu/uploads/lib/document/attachment/26/Boosting_building_renovation_-_Good_practices_BPIE_2013_small.pdf

8. http://www.stadtentwicklung.berlin.de/internationales_eu/staedte_regionen/download/BEEN_ResultsManual_english.pdf

9. http://ec.europa.eu/eip/smartcities/

10. http://ec.europa.eu/research/participants/portal/desktop/en/opportunities/h2020/topics/2148-scc-01-2015.html

11. http://www.districtoffuture.eu

12. Directive 2004/8/EC of the European Parliament and of the Council of February 11, 2004 on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC

13. http://www.getlini.lv/en/

Questions?

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Thank you!

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