Do-it-yourself wood-burning power plant, steam engine, Peltier principle

A wood-fired power plant is one of the alternative ways to supply consumers with electricity.

The device is capable of generating electricity at minimal energy costs, even in places where there is no power supply at all.

Such a power plant can be an excellent option for owners of summer cottages and country houses.

There are also miniature versions that are suitable for lovers of long hikes and pastimes in nature. But first things first.

Features

A wood-fired power plant is far from a new invention, but modern technologies have made it possible to somewhat improve the devices developed earlier. Moreover, several different technologies are used to generate electricity.

In addition, the concept of “wood burning” is somewhat inaccurate, since any solid fuel (wood, wood chips, pallets, coal, coke) is suitable for the operation of such a station, in general, everything that can burn.

We note right away that firewood, or rather the process of their combustion, acts only as an energy source that ensures the operation of the device in which electricity is generated.

The main advantages of such power plants are:

• The ability to use a wide variety of solid fuels and their availability;
• Getting electricity anywhere;
• The use of different technologies allows you to receive electricity with a variety of parameters (sufficient only for the usual recharging of the phone and before powering industrial equipment);
• It can also act as an alternative if power outages are common, as well as the main source of electricity.

Classic Edition

As already noted, several technologies are used in a wood-fired power plant to generate electricity. The classic among them is steam power, or simply the steam engine.

Everything is simple here – firewood or any other fuel, when burned, heats up water, as a result of which it passes into a gaseous state – steam.

The resulting steam is fed to the turbine of the generator set, and due to rotation, the generator generates electricity.

Since the steam engine and generator set are connected in a single closed circuit, after passing through the turbine, the steam is cooled, fed back into the boiler, and the whole process is repeated.

Such a power plant scheme is one of the simplest, but it has a number of significant drawbacks, one of which is explosiveness.

After the transition of water into a gaseous state, the pressure in the circuit increases significantly, and if it is not regulated, then there is a high probability of rupture of pipelines.

And although modern systems use a whole set of valves that regulate pressure, the operation of a steam engine still requires constant monitoring.

In addition, ordinary water used in this engine can cause scale formation on the pipe walls, which reduces the efficiency of the station (scale impairs heat transfer and reduces pipe throughput).

But now this problem is solved by using distilled water, liquids, purified impurities that precipitate, or special gases.

But on the other hand, this power plant can perform another function – to heat the room.

Everything is simple here – after performing its function (rotation of the turbine), the steam must be cooled so that it again turns into a liquid state, which requires a cooling system or, simply, a radiator.

And if you place this radiator indoors, then as a result, from such a station we will receive not only electricity, but also heat.

Other options

But the steam engine is just one of the technologies used in solid fuel power plants, and not the most suitable for domestic use.

Also used to generate electricity:

• Thermoelectric generators (using the Peltier principle);
• Gas generators.

Thermoelectric generators

Power plants with generators built according to the Peltier principle are quite an interesting option.

The physicist Peltier discovered the effect, which boils down to the fact that when electricity is passed through conductors consisting of two dissimilar materials, heat is absorbed at one of the contacts, and heat is released at the second.

Moreover, this effect is the opposite – if the conductor is heated on one side, and cooled on the other, then electricity will be generated in it.

It is the opposite effect that is used in wood-fired power plants. When burned, they heat up one half of the plate (it is a thermoelectric generator), consisting of cubes made of different metals, and its second part is cooled (for which heat exchangers are used), as a result of which electricity appears on the plate outputs.

But such a generator has several nuances. One of them is that the parameters of the released energy directly depend on the temperature difference at the ends of the plate, therefore, to equalize and stabilize them, it is necessary to use a voltage regulator.

The second nuance is that the energy released is only a side effect, most of the energy during the combustion of firewood is simply converted into heat. Because of this, the efficiency of this type of station is not very high.

The advantages of power plants with thermoelectric generators include:

• Long service life (no moving parts);
• At the same time, not only energy is produced, but also heat, which can be used for heating or cooking;
• Quiet operation.

Wood-fired power plants using the Peltier principle are a fairly common option, and are produced as portable devices that can only provide electricity to charge low-power consumers (telephone, flashlight), and industrial ones that can power powerful units.

gas generators

The second type is gas generators. Such a device can be used in several directions, including the generation of electricity.

It is worth noting here that such a generator in itself has nothing to do with electricity, since its main task is to produce combustible gas.

The essence of the operation of such a device is that in the process of oxidation of solid fuel (its combustion), gases are released, including combustible ones – hydrogen, methane, CO, which can be used for a variety of purposes.

For example, such generators were previously used on cars, where conventional internal combustion engines worked perfectly on the emitted gas.

Due to the constant rise in fuel prices, some motorists and motorcyclists have already begun to install these devices on their cars in our time.

That is, to get a power plant, it is enough to have a gas generator, an internal combustion engine and a conventional generator.

In the first element, gas will be released, which will become fuel for the engine, and that, in turn, will rotate the generator rotor in order to obtain electricity at the output.

The advantages of power plants on gas generators include:

• Reliability of the design of the gas generator itself;
• The resulting gas can be used to operate an internal combustion engine (which will become a drive for an electric generator), a gas boiler, a furnace;
• Depending on the involved internal combustion engine and electric generator, it is possible to obtain electricity even for industrial purposes.

The main disadvantage of the gas generator is the cumbersome design, since it must include a boiler, where all the processes for obtaining gas take place, a system for its cooling and purification.

And if this device is used to generate electricity, then the station should also include an internal combustion engine and an electric generator.

Representatives of factory-made power plants

It should be noted that these options – a thermoelectric generator and a gas generator are now a priority, therefore ready-made stations are produced for use, both domestic and industrial.

Below are a few of them:

• Furnace “Indigirka”;
• Tourist oven “BioLite CampStove”;
• Power plant “BioKIBOR”;
• Power plant “Eco” with gas generator “Cube”.

Furnace “Indigirka”.

An ordinary household solid fuel stove (made according to the Burzhayka stove type), equipped with a Peltier thermoelectric generator.

Perfect for summer cottages and small houses, because it is quite compact and can be transported in a car.

The main energy during the combustion of firewood goes to heating, but at the same time, the existing generator also allows you to get electricity with a voltage of 12 V and a power of 60 watts.

Печь «BioLite CampStove».

It also uses the Peltier principle, but it is even more compact (weight is only 1 kg), which allows you to take it on hiking trips, but the amount of energy generated by the generator is even less, but it will be enough to charge a flashlight or phone.

Power plant “BioKIBOR”.

A thermoelectric generator is also used, but this is already an industrial version.

The manufacturer, on request, can manufacture a device that provides output power from 5 kW to 1 MW. But this affects the size of the station, as well as the amount of fuel consumed.

For example, an installation that produces 100 kW consumes 200 kg of firewood per hour.

“Eco”.

But the Eco power plant is a gas generator. Its design uses a Cube gas generator, a gasoline internal combustion engine and a 15 kW electric generator.

In addition to industrial ready-made solutions, you can separately buy the same Peltier thermoelectric generators, but without a stove and use it with any heat source.

Homemade stations

Also, many craftsmen create home-made stations (usually based on a gas generator), which they then sell.

All this indicates that it is possible to independently make a power plant from improvised means and use it for your own purposes.

Next, consider how you can make the device yourself.

Based on thermoelectric generator.

The first option is a power plant based on a Peltier plate. We note right away that a home-made device is only suitable for charging a phone, a flashlight, or for lighting using LED lamps.

For manufacturing it will be required:

• A metal case that will play the role of a furnace;
• Peltier plate (sold separately);
• Voltage regulator with installed USB output;
• A heat exchanger or just a fan to provide cooling (you can take a computer cooler).

Making a power plant is very simple:

1. We make an oven. We take a metal box (for example, a computer case), unfold it so that the oven does not have a bottom. We make holes in the walls below for air supply. At the top, you can install a grate on which you can place a kettle, etc.
2. We mount the plate on the back wall;
3. We mount the cooler on top of the plate;
4. We connect a voltage regulator to the outputs from the plate, from which we power the cooler, and also draw conclusions for connecting consumers.

Everything works simply: we kindle firewood, as the plate heats up, electricity will be generated at its terminals, which will be supplied to the voltage regulator. The cooler will also start to work from it, providing cooling of the plate.

It remains only to connect consumers and monitor the combustion process in the stove (toss firewood in a timely manner).

Based on a gas generator.

The second way to make a power plant is to make a gas generator. Such a device is much more difficult to manufacture, but the power output is much greater.

For its manufacture will require:

• Cylindrical container (for example, a disassembled gas cylinder). It will play the role of a stove, so hatches should be provided for loading fuel and cleaning solid combustion products, as well as an air supply (a forced supply fan will be required to ensure a better combustion process) and a gas outlet.
• Cooling radiator (can be made in the form of a coil), in which the gas will be cooled.
• Capacity for creating a filter of the “Cyclone” type.
• Capacity for creating a fine gas filter.
• Gasoline generator set (but you can just take any gasoline engine).

After that, everything must be connected into a single structure. From the boiler, gas must flow to the cooling radiator, and then to the Cyclone and the fine filter. And only after that the resulting gas is supplied to the engine.

This is a schematic diagram of the manufacture of a gas generator. Execution can be very different.

For example, it is possible to install a mechanism for the forced supply of solid fuel from the bunker, which, by the way, will also be powered by a generator, as well as various control devices.

Creating a power plant based on the Peltier effect, there will be no special problems, since the circuit is simple. The only thing is that some safety measures should be taken, since the fire in such a stove is practically open.

But when creating a gas generator, many nuances should be taken into account, among them is ensuring tightness at all connections of the system through which the gas passes.

In order for the internal combustion engine to work normally, you should take care of high-quality gas purification (the presence of impurities in it is unacceptable).

The gas generator is a bulky design, so it is necessary to choose the right place for it, as well as ensure normal ventilation if it is installed indoors.

Since such power plants are not new, and they have been manufactured by amateurs for a relatively long time, a lot of reviews have accumulated about them.

Basically, they are all positive. Even with a home-made stove with a Peltier element, it is noted that it fully copes with the task. As for gas generators, the installation of such devices even on modern cars can be a good example here, which indicates their effectiveness.

Pros and cons of a wood-fired power plant

Wood-burning power plant is:

• Fuel availability;
• The ability to get electricity anywhere;
• The parameters of the received electricity are very different;
• You can make the device yourself.
• Among the shortcomings are noted:
• Not always high efficiency;
• Bulky design;
• In some cases, getting electricity is just a side effect;
• To generate electricity for industrial use, you need to burn a large amount of fuel.

In general, the manufacture and use of solid fuel power plants is an option that deserves attention, and it can become not only an alternative to electricity grids, but also help in places remote from civilization.