Sustainable Energy Successees

   

The Only Straw Heating Facility in Slovakia
The only straw burning facility in Slovakia is at a farm in Prasice (150 km north-east of Bratislava). PPD Prasice is an agricultural farm with 5,000 ha of arable land. The main business is production of wheat, but PPD also has about 100 cattle.

The decision to build a waste straw fired facility at this farm was made during the year of 1993. It was the result of consultation with AGROZET ZVOLEN which was involved in technical support for agro-business and one Czech company dealing with imports of agricultural technologies. The facility was proposed to be the first one in the former Czechoslovakia.

The decision to use straw as the fuel was not driven by environmental or financial reasons. There were no environmental problems with straw burned on the fields because it was almost completely used by agricultural farms or was simply left on fields for rottening.  Even the energy prices for heat were artificial low and agricultural farms received substantial support from the government. At this time, there were no real incentives to use this material just to substitute the oil or natural gas on an economical basis. Nevertheless, the decision to build this facility seems to be now the best one, which PPD Prasice has ever done.

Imported Technology
Because there were absolutely no experiences with straw firing facilities in former Czechoslovakia, it was decided to start up with simple one and manually operated boiler. The technology, including a 80-kW boiler (FARM 2000), was imported from British company Teisen Products Limited. The costs was around 640,000 Sk (16,000 EUR). All installations (plumbing and electrical work) were done by local companies and completed in 1994 when the boiler was put into the operation.

Straw-fired boiler installation

The boiler has chamber roof with a 2-stage combustion air supply system. Secondary air is pre-heated before being released into the combustion chamber to mix with the burning volatile gases, enabling the achievement of high temperatures, to give clean and complete combustion. (Low temperature combustion produces smoke, tar and excessive fuel consumption.). The high temperature exhaust gases pass through a multi-tube heat exchanger, transferring heat to the water before exhausting to the chimney at low temperature. No useful heat is lost unnecessarily to the chimney. The entire combustion process is thermostatically controlled and straw is only burned when required.

The boiler produces only heat. Heat is used on site for heating large workshop building (12 m x 80 m), 4 apartments recently used as offices and for warm water preparation.  All heated areas are connected to the boiler by good isolated pipeline. The temperature is set automatically and is regularly checked by the operator.

Simple Operation & Maintenance
During the heating season, which starts early autumn and ends at the end of spring, the straw is fed to the boiler 3 or 4 times a day. Each time one big bale (each bale of compressed straw measures 1,5 m in diameter with a depth of 1,8 m and weights up to 300 kg) is inserted into the boiler with the help of manually operated small crane car. The work is simple and is done by staff personal of PPD Prasice. The only thing to do by the operator (except of loading the bale) is to open the boiler’s door. Labor requires 15 minutes/bale and 1 hour/month for cleaning and ash removal.

Until now, local staff performs the necessary maintenance. The system has worked well with no major problems yet and the owner is more than satisfied. Even the necessary work related to manipulation with straw is considered as normal and there is no intention to change this for automatic operation. Straw is stored in a separate sheltered storehouse close to the boiler.

Smoke Under Control
From environmental point of view, simple burning straw can create some problems with smoke. Straw firing facility in Prasice uses only dry straw which improves the burning conditions and emissions are filtered before entering the chimney. The emissions were measured by regional environmental agency and are kept below national limits. According to the supplier of technology the boiler is able to operate in smokeless zones.

Benefits, savings
The real benefits of straw firing are clear today. Straw is just free fuel source for PPD Prasice and is baled directly behind the combine harvester. If not used as the fuel it would be just waste. Prices of natural gas (the usual fuel source in such kinds of farms) are increasing in Slovakia which put many farms close to the edge of their survival.

The owner did not estimate the total savings until yet but the investment costs have long been paid off. According to recent price of natural gas and resulted heating costs, the payback time of such a facility would be 3 or 4 years. Annual heat savings are around 150,000 Sk (3,800 EUR).

There is only small amount of ash from burning the straw and it is all used as fertilizer on fields. Moreover, savings are achieved due to cutting cost of ploughing-in of surplus straw.
 

Why No More Plants?
It is quite surprising that there are no other such facilities of this kind in Slovakia. PPD Prasice expressed their satisfaction during several regional or national seminars on biomass. One obvious reason for this is that the Slovak agricultural farms still prefer to make pressure on government to get funding than to come up with savings measures. Other reasons are the lack of relatively cheap bank loans, the missing key orientation on agro business, and the lack of interest on energy issues.