Micro combined heat and power or micro-CHP or mCHP is an extension of the idea of cogeneration to the single / multi family home or small office building in the range of up to 50 kW. Local generation has the potential for a higher efficiency than traditional grid-level generators since it lacks the 8-10% energy losses of transporting electricity over long distances. It also lacks the 10-15% energy losses of heat transfer in the district heating networks due to the difference between the thermal energy carrier (hot water) and the colder external environment. The most common systems use their primary source of energy and emit carbon dioxide.
Combined heat and power (CHP) systems for homes or small commercial buildings are often fueled by natural gas to produce electricity and heat. A micro-CHP system usually contains a small fuel cell or a heat engine as it is used to power a generator, while simultaneously utilizing the waste heat of an individual heating, ventilation, and air conditioning . A micro-CHP generator can primarily follow heat demand, delivering electricity by the product, or can be used as a generator. Where used primarily for heating, micro-CHP systems The heat engine is a small scale example of cogeneration schemes which have been used with large electric power plants. The purpose of cogeneration is to use more energy in the fuel. The reason for using such systems is that heat engines, such as steam power plants, which are not very efficient. Due to Carnot’s theorem, a heat engine can not be 100% efficient; it can not be converted to any form of energy. Therefore, heat engines always produce a surplus of low-temperature waste heat, called “secondary heat” or “low-grade heat”. Modern plants are limited to efficiencies of about 33-63% at most, so 37-67% of the energy is exhausted as waste heat. In the past this energy was usually wasted to the environment. Cogeneration systems, built in recent years in cold-climate countries, utilize the waste heat produced by large power plants for heating by piping hot water from the plant into buildings in the surrounding community. However, it is not practical to transport heat long distances due to heat loss from the pipes. Since electricity can be transported practically, it is more efficient to generate electricity where waste heat can be used. So in a “micro-combined heat and power system” (micro-CHP), small power plants are located where the secondary heat can be used, in individual buildings. Micro-CHP is defined by the EC as being less than 50 kW electrical power output, however, others have more restrictive definitions, all the way down to <5 kWe. In centralized power plants, the supply of “waste heat” may exceed the local heat demand. In such cases, if it is not desirable to reduce the power production, the excess waste heat must be disposed of (eg cooling towers or sea cooling) without being used. A way to avoid excessive waste heat is to reduce the fuel input to the CHP plant, reducing both the heat and power output to balance the heat demand. In doing this, the power production is limited by the heat demand. Such a source of electricity, such as biomass, coal, solar thermal, natural gas, petroleum or uranium, % for very old plants and 45% for newer gas plants. In contrast, a CHP system converts 15% -42% of the primary heat to electricity, and most of the remaining heat is captured for hot water or space heating. In total, over 90% of the primary heat source (LHV based) can be used when heat production does not exceed the thermal demand. CHP systems are able to increase the total energy utilization of primary energy sources, such as fuel and concentrated solar thermal energy. Thus CHP has been steadily gaining popularity in all sectors of the energy economy, due to the increased costs of electricity and fuel, particularly fossil fuels, and due to environmental concerns, particularly climate change. CHP systems have benefited the industrial sector since the beginning of the industrial revolution. For three decades, these larger CHP systems were more economically justifiable than micro-CHP, due to the economy of scale. After the year 2000, micro-CHP has become effective in many markets around the world, due to rising energy costs. The development of micro-CHP systems has also been facilitated by recent developments. Stirling engines, steam engines, gas turbines, diesel engines and Otto engines. PEMFC fuel cell mCHP operates at low temperature (50 to 100 ° C) and needs high purity hydrogen, its prone to contamination, changes to make it work at higher temperatures and improvements on the fuel reformer. SOFC fuel cell mCHP operates at a high temperature (500 to 1,000 ° C) and can handle different energy sources. changes are made to operate at a lower temperature. Because of the higher temperature SOFC in general has a longer start-up time and needs continuous heat output even when there is no thermal demand. CHP systems linked to absorption chillers A 2013 UK report from Ecuity Consulting stated that MCHP is the most cost-effective method of utilizing gas to generate energy at the domestic level. Delta-ee consultants stated in 2013 that with 64% of global sales the fuel cell micro-combined heat and power passed the 2012-based micro-CHP systems in sales in 2012. CHP systems linked to absorption chillers A 2013 UK report from Ecuity Consulting stated that MCHP is the most cost-effective method of utilizing gas to generate energy at the domestic level. Delta-ee consultants stated in 2013 that with 64% of global sales the fuel cell micro-combined heat and power passed the 2012-based micro-CHP systems in sales in 2012. CHP systems linked to absorption chillers A 2013 UK report from Ecuity Consulting stated that MCHP is the most cost-effective method of utilizing gas to generate energy at the domestic level. Delta-ee consultants stated in 2013 that with 64% of global sales the fuel cell micro-combined heat and power passed the 2012-based micro-CHP systems in sales in 2012.
Micro-CHP engine systems are currently based on several different technologies:
There are many types of fuels and sources of heat that can be considered for micro-CHP. The properties of these sources vary in terms of system cost, heat cost, environmental effects, convenience, ease of transportation and storage, system maintenance, and system life. Some of the heat sources and fuels that are being considered for micro-CHP include: natural gas, LPG, biomass, vegetable oil (such as rapeseed oil), woodgas, solar thermal, and additionally hydrogen, as well as fuel systems. The energy sources with the lowest emissions of particulates and net-carbon dioxide include solar power, hydrogen, biomass (with two-stage gasification into biogas), and natural gas. Due to the high efficiency of the CHP process, cogeneration has still lower carbon emissions compared to energy transformation in fossil driven gold boilers thermal power plants. The majority of cogeneration systems use natural gas for fuel, because natural gas burns easily and cleanly, it can be inexpensive, it is available in most areas and is easily transported through pipelines which already exists for over 60 million homes.
Reciprocating internal combustion engines are the most popular type of engine used in micro-CHP systems. Reciprocating internal combustion engine based systems can be used to increase the efficiency of the machine. However, since they have reciprocated internal combustion engines, they have the ability to modulate their power output by changing their operating speed and fuel input, micro-CHP systems based on these engines can have varying electrical and thermal output designed to meet changing demand. Natural gas is suitable for internal combustion engines, such as Otto engine and gas turbine systems. Gas turbines are used in many small systems due to their high efficiency, small size, clean burning, durability and low maintenance requirements. Gas turbines designed with foil bearings and air-cooling operate without lubricating oil or coolants. The waste heat of gas turbines is mostly in the exhaust, while the waste heat of reciprocating internal combustion engines is split between the exhaust and cooling system. External combustion engines can run on any high-temperature heat source. These engines include the Stirling engine, hot “gas” turbocharger, and the steam engine. Both range from 10% -20% efficiency, and as of 2014, small quantities are in production for micro-CHP products. Other possibilities include the Organic Rankine Cycle, which operates at lower temperatures and pressures using low-grade heat sources. The primary advantage is that the equipment is essentially an air-conditioning or refrigeration unit means the piping and other components need not be designed for extreme temperatures and pressures, reducing cost and complexity. Electrical efficiency suffers, but it is presumed that such a system would be used to heat the boiler or to heat it. The future of combined heat and power, particularly for homes and small businesses, will continue to be affected by the price of fuel, including natural gas. As fuel prices continue to climb, it will be more economical, and more efficient energy use, including CHP and micro-CHP. It would be presumed that such a system would be used to heat the boiler or to heat it. The future of combined heat and power, particularly for homes and small businesses, will continue to be affected by the price of fuel, including natural gas. As fuel prices continue to climb, it will be more economical, and more efficient energy use, including CHP and micro-CHP. It would be presumed that such a system would be used to heat the boiler or to heat it. The future of combined heat and power, particularly for homes and small businesses, will continue to be affected by the price of fuel, including natural gas. As fuel prices continue to climb, it will be more economical, and more efficient energy use, including CHP and micro-CHP.
Fuel cells generate electricity and heat by product. The advantages for a stationary fuel cell application over stirling CHP are no moving parts, less maintenance, and quieter operation. The surplus electricity can be delivered back to the grid. PEMFC fuel cells fueled by natural gas or propane use a steam reformer to convert methane into the gas supply into carbon dioxide and hydrogen; the hydrogen then reacts with oxygen in the fuel cell to produce electricity. A PEMFC fuel cell based micro-CHP has an electrical efficiency of 37% LHV and 33% HHV and a heat recovery efficiency of 52% LHV and 47% HHV with a service life of 40,000 hours or 4000 start / stop cycles which is equal to 10 year use. An estimated 138,000 Fuel cell CHP systems below 1 kW had been installed in Japan by the end of 2014. Most of these CHP systems are PEMFC-based (85%) and the remaining SOFC systems. In 2013 Lifetime is around 60,000 hours. For PEM fuel cell units, which shut down at night, this equates to an estimated lifetime of between ten and fifteen years. United States Department of Energy (DOE) Technical Targets: 1-10 kW residential combined heat and power fuel cells operating on natural gas. 1 Standard utility natural gas delivered at typical residential distribution line pressures. 2 Regulated AC net / lower heating value of fuel. 3 Only heat available at 80 ° C or higher is included in CHP energy efficiency calculation. 4 Cost includes production and production costs. Cost defined at 50,000 unit / year output (250 MW in 5 kW modules). 5 Based on operating cycle to be released in 2010.
Thermoelectric generators operating on the Seebeck Effect show promised to their total absence of moving parts. Efficiency, however, is the most important thermoelectric devices to achieve high efficiency.
This invention can be achieved by photovoltaic thermal hybrid solar collector, another option is Concentrated photovoltaics and thermal (CPVT), also known as combined heat and power solar (CHAPS), is a cogeneration technology used in same module. The heat may be employed in district heating, water heating and air conditioning, desalination or process heat. CPVT systems are currently in production in Europe, with Zenith Solar developing CPVT systems with a claimed efficiency of 72%. Sopogy produces a micro-concentrated solar power (microCSP) system that can be installed above or can be installed, or the heat can be used for water heating or solar air conditioning, a steam turbine can also be installed to produce electricity.
The recent development of small scale CHP systems has provided the opportunity for in-house power backup of residential-scale photovoltaic (PV) arrays. The results of a recent study show that PV + CHP hybrid system not only has the potential to radically reduce energy in the status quo electrical and heating systems, but also enables the share of solar PV five. In some regions, in order to reduce waste from excess heat, an absorption has been proposed to utilize the CHP-produced thermal energy for cooling of PV-CHP system. These trigens + PV systems have the potential to save even more energy.
To date, micro-CHP systems achieve much of their savings, and thus attractiveness to consumers, by the value of electrical energy, which is replaced by the autoproduced electricity. A “generate-and-resell” or net metering model supports this home-generated power exceeding the instantaneous in-home needs. This system is efficient because the energy used is distributed and used instantaneously over the electrical grid. The main losses are in the transmission from the source to the consumer which will typically be less than the losses incurred by storing energy or generating power at the peak efficiency of the micro-CHP system. So, from a purely technical standpoint, dynamic demand management and net-metering are very efficient. Another positive to net-metering is the fact that it is fairly easy to configure. The user’s electrical meter is simply able to record electrical power. As such, it records the net amount of power entering the home. For a grid with relatively few micro-CHP users, no design changes to the electrical grid need be made. Additionally, in the United States, to compensate anyone adding power to the grid. From the standpoint of grid operator, these points are operational and technical as well as administrative burdens. As a result, most grid operators compensate non-utility power-contributors and charge their customers. While this compensation scheme may be it only represents the consumer’s cost-savings of not purchasing utility power versus the true cost of generation and operation to the micro-CHP operator. So from the standpoint of the micro-CHP operators, net-metering is not ideal. While net-metering is a very efficient mechanism for using excess energy generated by a micro-CHP system, it does have detractors. Of the detractors’ main points, the first to consider is that the source of the generation is large commercial generator, net-metering generators “spill” power to the smart grid in a haphazard and unpredictable fashion. However, the effect is negligible if there is only a small percentage of electricity and a relatively small amount of electricity. When turning on an oven or space heater, The same amount of electricity is drawn from the grid as a home generator puts out. If the percentage of people with genes becomes large, then the effect on the grid may become significant. Coordination among the generating systems in homes and the rest of the grid may be necessary.
The largest deployment of micro-CHP is in Japan in 2009 where over 90,000 units in place, with the vast majority being of Honda’s “ECO-WILL” type. Six Japanese energy companies launched the 300 W-1 kW PEMFC / SOFC ENE FARM product in 2009, with 3,000 installed units in 2008, a production target of 150,000 units for 2009-2010 and a target of 2,500,000 units in 2030. 20,000 units where sold in 2012 overall within the Ene Farm project making an estimated total of 50,000 PEMFC and up to 5,000 SOFC facilities. For 2013 a state subsidy for 50,000 units is in place. The ENE FARM project will pass 100,000 systems in 2014, 34,213 PEMFC and 2,224 SOFC were installed in the 2012-2014 period, 30,000 units on LNG and 6,000 on LPG.
2013, installed in a total of 131,000 homes. Manufactured by Honda using their single cylinder EXlink engine capable of burning natural gas or propane. Each unit produces 1 kW of electricity and 2.8 kW of hot water.
In South Korea, grants will start at 80 percent of the cost of a domestic fuel cell. The Renewable Portfolio Standard program with renewable energy certificates runs from 2012 to 2022. Quota systems favor large, vertically integrated generators and multinational electric utilities, if only because of denominated in units of one megawatt-hour. They are also more difficult to design and implement than a Feed-in tariff. Around 350 residential mCHP units where installed in 2012.
The European public-private partnership Fuel Cells and Hydrogen Joint Undertaking Seventh Framework Project ene.field aims to deploy by 2017 up to 1,000 residential fuel cell Combined Heat and Power (micro-CHP) facilities in 12 EU member states.
Powercell Sweden is a fuel cell company that develops environmentally friendly electric generators with a unique fuel cell technology that is suitable for both existing and future fuel.
In Germany, 50 MW of mCHP up to 50 kW units have been installed in 2015. The German government is offering a wide range of CHP incentives, including a market premium on electricity generated by CHP and an investment bonus for micro-CHP units. The German testing project Callux has 500 mCHP facilities by Nov 2014. North Rhine-Westphalia launched a 250 million subsidy program for up to 50 kW lasting until 2017.
It is estimated that about 1,000 micro-CHP systems were in operation in the UK as of 2002. These are primarily Whispered using Stirling Engines, and Senertec Dachs Reciprocating Engines. The Energy Saving Trust and Carbon Trust, which is one of the world’s largest financial services companies, is one of the most important sources of revenue. Effective as of 7 April 2005, the UK government has cut the VAT for 20% to 5% for micro-CHP systems, in order to support demand for this emerging technology of the expense of existing, environmentally friendly technology. The reduction in VAT is effectively a 10.63% subsidy for micro-CHP units over conventional systems, which will help micro-CHP units become more cost competitive, and ultimately drive micro-CHP sales in the UK. Of the 24 million households in the UK, as many as 14 to 18 million are thought to be suitable for micro-CHP units. Two fuel cell types of mCHP co-generation units are almost ready for mainstream production and are planned for release to market in early 2014. With the UK Government’s Feed-In-Tariff available for a 10-year period, a wide uptake of the technology is anticipated.
The Danish mCHP project 2007 to 2014 with 30 units is on the island of Lolland and in the western town Varde. Denmark is currently part of the Ene.field project.
The micro-CHP subsidy was ended in 2012. To test the effects of mCHP on a smart grid, 45 natural gas SOFC units (each 1.5 kWh) from Republiq Power (Ceramic Fuel Cells) will be placed on Ameland in 2013 to function as a virtual power plant.
The federal government is offering a 10% tax credit for smaller CHP and micro-CHP commercial applications. In 2007, the United States company “Climate Energy” of Massachusetts introduced the “Freewatt, a micro-CHP system based on a Honda MCHP engine bundled with a gas furnace (for warm air systems) or boiler (for hydronic or forced hot water heating systems by Eden Oak with support from ECR International, Enbridge Gas Distribution and National Grid Marathon Engine Systems, a Wisconsin company , produced a variable electrical and thermal output micro-CHP system called the ecopower with an electrical output of 2.2-4.7 kWe.The ecopwer was independently measured to operate at 24.4 and 70.
* Hyteon PEM
CNG net distribution, the appliances involved are kitchen stoves, condensing boilers, and micro-CHP boilers. Micro-CHP Accelerator, a field trial performed between 2005 and 2008, studied the performance of 87 Stirling engine and internal combustion engine devices in residential houses in the UK. This study found that the devices result in average carbon savings of 9% for houses with heat demand over 54 GJ / year. An ASME (American Society of Mechanical Engineers) paper presented the performance and operating experience with two built-up units in the United States of America. Advanced Research Project Agency – Energy (ARPA-e), tested the state of the art micro-CHP systems in the United States. The results showed that nominally 1 kWe state-of-the-art micro-CHP system operated at an electrical and total efficiency (LHV based) of 23.4 and 74.4%, respectively. The nominally 5 kWe state-of-the-art system operates at an electrical and total efficiency (LHV based) of 24.4 and 94.5%, respectively. The most popular 7 kWh home backup generator (not CHP) operating at an electrical efficiency (LHV based) of 21.5%. The price of the emergency backup generator has been reduced to 5 kWe generator, but the projected power of the system has been reduced to 2 orders of magnitude lower. These results show the trade-off between efficiency, cost, and durability. The US Department of Energy Advanced Research Project Agency – Energy (ARPA-e) has funded $ 25 million towards mCHP research in the GENerators for Small Electrical and Thermal Systems (GENSETS) program. 12 project teams have been selected to develop a 1 kWe mCHP technology that can achieve 40% electrical efficiency, have a 10-year system life, and cost under $ 3000.