Heat supply technologies with biomass:

In our country, we basically recommend two types of biomass for the heat supply of homes, institutions or even central heating plants: pellet and wood cutting. We briefly present the combustion techniques of the two biomass energy sources in a comprehensible manner:

Technology of pellet combustion:

The primary fuel for heating technology may be agricultural, forestry and forestry-based by-products or wastes, which are pressed into small-sized rods – called pellet – and usually marketed as such in packed bags.

The pellet goes from the bag to the container installed in (or next to) the boiler:

The pellet is transferred from the container to the boiler by the below transfer structure (transferor screw and its drive powered by an electric engine):

The conversion of the pellet to heat happens for example in the below pellet boiler:

The advantage of pellet combustion is its clean handling, the process can be automatized and its operational costs are less than that of gas combustion. It is especially appropriate for the heat supply of flats – even centrally located – or individual institutions.

The technology of wood-cutting combustion

The primary substance can be forestry related by-products (e.g. edging from the furniture industry), forestry waste, cut trees (selejtezett faállomány) or tree stands of planted energy forestry. The technology begins with the collection, deposition and cutting of the scrap wood. The cutting may be done with a mobile equipment at the forestry site which also facilitates the transport. mobile cutting equipment powered by a tractor’s hydraulics (Type Biber 3):

As for the storage of the wood cutting, it is preferable to establish a larger and covered container. The cutting may be transferred from the storage to the boiler’s daily container by a shovel loader with the involvement of one worker or by an installed chain-driven transfer equipment.

The process of the technology is illustrated by the below schematic drawing.

A wood cutting combustion equipment is illustrated by the below drawing:

The key advantage of wood cutting combustion is that it is 50 % cheaper than gas and capable of creating job opportunities.A disadvantage is its relatively high demand of logistics area; however it is capable of producing media of any secondary temperatures thus may replace crude gas in 100 %. It is especially suitable for central heating plants and as primary source of energy for boiler houses.

Heat supply technologies with geothermal energy:

The tool of obtaining geothermal energy is a drilling equipment, the tool of passing it to the heat market is an insulated grid installed underground and the tool of the heat supply to the heating system is a plate heat exchanger:

Obtaining geothermal energy may be achieved by the exploitation of deep thermal water stocks or by the circulation of surface water in 5,000-6,000 m deep dry wells. The latter is economically not competitive due to its high costs and it is in experimental phase worldwide. In our country, in greater depths (1.000 – 2.500 m) only the thermal water method is accessible.

Utilization of thermal energy from greater depth can only be economic within a complex approach, establishing a cascade heat market system thereby minimalizing the relative heat extraction. Its competitiveness can be improved if the energetic utilization is supplemented by its usage in balneology. The optimal heat markets of such systems are central heating systems concentrated within heating plants, large institutions, horticultures and public bathes which may be heated in lower temperature levels.

The geothermal heat supply systems of separate smaller buildings are heat pumps which are illustrated by the below drawing (Dickson and Fanelli 2003, Judit Mádlné Szőnyi 2006, Tímea Tarkovács 2010):

With the help of heat pumps, the utilization of units of relatively low temperature (ground-water, water layer, cooled thermal water, etc.) has become economically profitable. Heat pumps are equipments that force heat to flow in the opposite direction of its natural flow, that is from the colder unit to the warmer unit.The heati pump is actually a huge cooling machine. As we know, cooling machines extract heat from the cooled space and release it at a higher temperature.

Of course this requires energy. Ehhez természetesen energiára van szükség. By optimal climate circumstances and smart planning the energy balance may be positive. Today, heat pumps attached to the ground or ground water operate in 27 countries, (USA, Switzerland, Sweden, Canada, Germany, Austria) producing a total of 6,875 MWt energy (see drawing). They use the heat content of grounds of 5-30 °C temperature or shallow aquifers.

For the transfer of heat, continuous electricity has to be supplied to the system. The efficiency of the system can be described by the COP (coefficient of performance) ratio that shows the ratio of the heating performance over the energy consumed throughout the operation. However, this may vary during the year due to the changes of the temperature of the heat source therefore a more accurate picture can be provided by the yearly energy efficiency ratio (JAZ - Jahresarbeitzahl) over the performance of the heat pump. This largely depends on the temperature gap that has to be overtaken (the difference between the heat source and the heating flow temperature), it is usually a value between four and seven which means that four-seven units of heat energy can be produced by one unit of electricity (in spite of the electric heating whereas one unit of heat energy can be produced by one unit of electricity).

Primarily, the low temperature heating methods are appropriate for the usage with heat pumps because the efficiency of the system is better if the heating flow temperature is lower - just like in the case of sun collectors. Optimal heating methods are floor-, wall-, ceiling- or fan coil heating whereas 35-50 °C temperature is sufficient.

What to choose?

The question can be answered after thorough preliminary examinations, depending on the local geological circumstances, the availability of biomass resources and logistics, the parameters of the heat cunsuming systems, the intention and determination of the investors in light of their financial resources.

The optimal solution shall be decided by the exact analysis of the different options.

Should you have any inquiries, our company is at your disposal to share with you our planning and operating expertise. Feel free to contact us.