Gas boiler with electric generator: device, principle of operation, review of the best brands

A careful attitude to energy resources is dictated primarily by the fact that almost all natural reserves are not infinite.Economical consumption of all types of fuel requires the development of new systems or radical modernization of existing ones.

Thus, a gas boiler with an electric generator is one of the types of hybrid systems that allow you to intelligently manage blue fuel. We will introduce you to the operating principle of equipment that produces electrical energy along with thermal energy. Let's imagine typical models of hybrid units.

Efficient energy consumption

Even the average person who has a gas boiler installed for heating their home may wonder about the rational use of thermal energy. Indeed, when gas is burned in a boiler, not all of the heat generated is used.

When a heating system operates, some part of the heat is always lost irretrievably. This usually happens when combustion products are released from the boiler into the atmosphere. In fact, this is wasted energy that could have been used.

What exactly are we talking about? On the possibility of using wasted “wasted” heat in the production of electrical energy.

If we assume that the heating boiler system is already optimized in order to maximize efficiency, then the “discarded” energy still constitutes a significant proportion of the energy that is released during fuel combustion

The types of fuel can be different, starting with banal firewood and all kinds of briquettes, ending with the most economical options: main gas with a predominance of methane in its composition, artificial blue fuel and liquefied propane-butane mixtures.

It may seem that this is far from the “discovery of America,” but in fact, the technology, or rather, the installation, developed back in 1943 by Robert Stirling, exists. Its design features and basic operating principle make it possible to classify this system as an internal combustion engine.

Why then was this installation not used for such a significant time? The answer is simple - the theoretical development of technology in the forties of the last century turned out to be very cumbersome in practice.

The technologies and materials that existed at the time of development did not allow reducing the size of the installation, and the existing methods of producing electrical energy were more cost-effective.

Including a device in a gas boiler circuit that converts wasted heat into electricity can significantly increase the efficiency of a gas processing plant.

What can make us today think about a more careful attitude towards resources that are not classified as renewable? Nowadays there is a common problem all over the world - the development of technology inevitably leads to an increase in the consumption of electrical energy.

The increase in consumption is happening at such a rapid pace that network companies do not have time to modernize electrical energy transmission systems, not to mention production.This situation inevitably leads to the fact that elements of power supply systems fail, and in some cases this can happen with enviable regularity.

Modern heating boilers are equipped with control systems that are also energy-dependent. The circulation pump, sensors, automation, and the panel itself need power. The entire set of devices cannot but cause concern for maintaining functionality during a power outage.

It is not possible to run forced heating systems without electricity. A power outage during the heating season is almost catastrophic for them. Not only will this inevitably lead to rapid cooling of the room, but if the heating is not operating for a long time, the circuit may freeze.

A prolonged absence of operation of the heating system during the cold season leads to freezing of the heating system, the appearance of ice plugs in it and, ultimately, damage to equipment and heating pipes due to rupture

Standard existing options for resolving the issue - installation uninterruptible power supplies, generators of various modifications (gas, petrol, diesel generators or non-traditional sources - wind generators or mini thermal power plants, hydroelectric power stations).

But this solution is not acceptable to everyone, since many find it difficult to allocate space for installing an autonomous electricity supplier.

While residents of individual houses can still allocate space for a generator, this is almost impossible for installation in a multi-storey building. Thus, it turns out that residents of apartment buildings with individual heating systems are the first to suffer when the power goes out.

That is why, first of all, companies that produce components for assembling heating systems have asked themselves the question of making full use of the heat that is “thrown away” by the heating system. We thought about how to use this wasted substance to generate electricity.

Of the well-known technologies, the developers chose the “well-forgotten” Stirling installation; modern technologies make it possible to increase its efficiency while maintaining a compact size.

The principle of operation of the Stirling engine is the movement of the engine piston down and up. The engine operates almost silently and does not cause equipment vibrations

The operating principle of the Stirling installation is based on the use of heating and cooling of the working fluid, which in turn activates a mechanism that generates electrical energy.

Inside the piston (closed) there is a pumped gas; when heated, the gaseous medium expands and moves the piston in one direction; after cooling in the cooler, it contracts and moves the piston in the other direction.

Review of manufacturers of boilers with generators

Let's look at specific examples of domestic boiler systems that exist today, in which the principle of using exhaust gases (combustion products) to produce electricity has been successfully implemented. The South Korean company NAVIEN has successfully implemented the above technology in a boiler of the HYBRIGEN SE brand.

The boiler uses a Stirling engine, which, according to the passport data, generates electricity with a power of 1000W (or 1kW) and a voltage of 12V during operation. The developers claim that the generated electricity can be used to power household appliances.

This power should be enough to power a household refrigerator (about 0.1 kW), a personal computer (about 0.4 kW), an LCD TV (about 0.2 kW) and up to 12 LED light bulbs with a power of 25 W each.

Boiler of the hybrigen se series from navien with a built-in generator and Stirling engine. When the boiler is operating, in addition to its main functions, electricity of about 1000 W of power is generated

Of the European manufacturers, Viessmann is developing in this direction. Viessmann has the opportunity to offer consumers a choice of two models of boilers of the Vitotwin 300W and Vitotwin 350F series.

The Vitotwin 300W was the first development in this direction. It is distinguished by a fairly compact design and is very similar in appearance to a conventional wall-mounted gas boiler. True, it was during the operation of the first model that the “weak” points in the operation of the Stirling engine were identified.

The biggest problem turned out to be heat removal; the basis of the device’s operation is heating and cooling. Those. the developers faced the same problem that Stirling faced in the forties of the last century - effective cooling, which can only be achieved with a significant size of the cooler.

That is why the Vitotwin 350F boiler model appeared, which included not only a gas boiler with an electricity generator, but also a built-in 175 liter boiler.

The storage tank for hot water is made in a floor-mounted version due to the large weight of both the equipment itself and the liquid prepared for sanitary purposes

In this case, the issue with the problem of cooling the piston of the Stirling installation due to water in boiler. However, the decision led to an increase in the overall dimensions and weight of the installation. Such a system can no longer be mounted on the wall like a conventional gas boiler and can only be floor-mounted.

Viessmann boilers provide the possibility of feeding the boiler operating systems from an external source, i.e. from central power supply networks. The Viessmann company positioned the equipment as a device that provides its own needs (operation of boiler units) without the possibility of selecting excess electricity for domestic consumption.

The Vitotwin F350 system is a boiler with a water heating boiler with a volume of 175 liters. The system allows you to heat the room, provides hot water and generates electrical energy

In order to compare the efficiency of using generators built into the heating system. It is worth considering the boiler, which was developed by the TERMOFOR companies (Republic of Belarus) and the Kryotherm company (Russia, St. Petersburg).

They are worth considering not because they can somehow compete with the above systems, but to compare the operating principles and efficiency of generating electrical energy. These boilers use only wood as fuel, pressed sawdust or wood-based briquettes, so they cannot be put on a par with models from NAVIEN and Viessmann.

The boiler, called “Heating stove “Indigirka”, is aimed at long-term heating with wood, etc., but is equipped with two thermal electricity generators of the TEG 30-12 type. They are located on the side wall of the unit. The power of the generators is small, i.e. in total they are only able to generate 50-60W at 12V.

The basic design of the Indigirka stove allows you not only to heat the room, but also to cook food on the burner. The system is complemented by two 12V heat generators with a power of 50-60W.

In this boiler, the Seebeck method, based on the formation of an emf in a closed electrical circuit, was used. It consists of two dissimilar types of material and maintains contact points at different temperatures. Those. developers also use the heat generated by the boiler to generate electrical energy.

Boiler efficiency comparison

Comparing the presented types of boilers, which not only heat the room (heat coolant), but also generate electricity through the use of generated heat, attention should be paid to important aspects during operation.

Both the NAVIEN company and the Viessmann company position their boilers, pointing out the undoubted advantages - complete automation of the process, no need for service repairs and generally a complete lack of intervention after commissioning by the buyer.

For the operation of these boilers, all that is needed is stable operation of the system and stable availability of gas (whether it be main supplies, a bottled installation with liquefied gas or gas holder). Accordingly, domestic gas is used to operate boilers, which after combustion does not pose any harm to the environment.

In principle, almost the same can be said about the Indigirka heating stove, only the type of fuel here is not gas, but firewood, pellets or pressed sawdust.

Complete absence automationwhich requires electricity. The electrical energy generation system and the boiler itself do not affect each other’s operation, i.e.If the electricity production system fails, the boiler continues to perform its functions.

All of these gas-processing heating units, with Stirling engines located under the burners, produce electrical energy that can be used for various purposes

Boilers from NAVIEN and Viessmann cannot boast of this, since the Stirling engine is built directly into the boiler design. But how profitable are such systems and how long will it take for such a boiler to pay for itself? This issue is worth understanding in detail.

Profitability of the systems under consideration

At first glance, boilers from NAVIEN and Viessmann are practically mini-thermal power plants in a private house or even an apartment.

Even despite the large overall dimensions, the ability to produce electrical energy simply by using a boiler to heat a boiler or heat rooms should prompt the buyer to install such a “miracle of technology” without hesitation.

But upon closer examination of the NAVIEN boiler, questions arise that require answers. With a declared power of 1 kW (free power that can be used at your discretion), the boiler quite noticeably consumes electricity when the system is operating.

What is meant? At a minimum, the automation works, although a little power is needed, but it is needed for the fan and circulation pump to function. The listed devices in total can not only successfully consume this kilowatt of energy, but it may not be enough when “overclocking” the system.

Schematic diagram of the Vissmann Vitotwin 350F heating system with a 175 liter floor boiler.The system allows you to both use electricity from an external source and distribute excess generated electricity to the general network

Exactly the same questions arise regarding Viessmann boilers, but at least the possibility of extracting electricity for one’s own needs was not stated here. Only the possibility of autonomous operation of the system in the absence of external supply was stipulated.

Although the developers immediately point out that “the system may require additional electrical power at peak loads.” Against the background of the declared 3500 kWh of electricity produced per year, this nuance is already in doubt, but through simple and simple calculations we get the following:

3500:6 (months of the standard heating season): 30 (30 calendar days on average): 24 (24 hours in a day) = 0.81 kW*hour.

Those. The boiler produces about 800 W during stable (constant) operation, but how much does the system itself consume during operation? Perhaps the same ones, producing 800W, and perhaps more.

In addition, electricity is generated only during the operation of the burner. Those. Either constant operation of the system is required, or everything is a little different from what the system developers say.

What did these calculations lead to? The wood boiler system actually produces its 50Wh (or 0.05kWh), which can be used to recharge a tablet, phone, etc. even for a banal “duty LED light bulb”. In contrast to the developments of two world-famous companies, the developments described clearly look more like a good marketing ploy, and nothing more.

As for the pricing policy for these systems, it’s generally difficult to evaluate anything.Because even manufacturing companies Viessmann and NAVIEN immediately stipulate that the equipment “does not require maintenance.” Translated into simple language, it’s broken, which means the unit needs to be replaced completely.

This may not apply to the entire system, but to individual components: the Stirling engine, the gas burner system, etc. The result will be quite an impressive amount. Assuming that the average price for these systems is about 12 thousand. euros or 13.5 thousand $. The scheme of operation of a boiler with a generator, then only the system manufacturer can win in such a situation.

The Indigirka stove cannot participate in the comparison at all, not only because the type of fuel is not gas, and the price is not comparable (15 times less), but because the stove is positioned not for domestic use, but more for travel, expeditions, etc. .P.

If in Europe the energy situation quite significantly influences consumer choice (when choosing heating or energy supply systems) from the point of view of efficiency and environmental friendliness, then the EU states stimulate this by subsidizing the implementation of such systems.

For household consumers in Russia, such systems will most likely be too expensive, both initially “system + installation” and during operation.

Conclusions and useful video on the topic

The operating principle of a Stirling engine equipping a gas boiler:

Demonstration of the operation of a gas boiler with an electricity generator:

An example of a wood stove with an electricity generator for comparison with a gas unit:

Do not forget that European energy generating companies are quite loyal to the “manufacturers” of energy-saving equipment.

In Russia, the possibility of generating and transmitting electrical energy to the grid by household consumers is not only not enshrined in law, but is also not welcomed by grid companies. Therefore, the presented systems are unlikely to have a serious chance of being used in the Russian Federation today.

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