An important technology of energy generation is fermentation of biomass to produce biogas. One of the advantages of this technologies is utilization of the municipal and agricultural waste that provides valuable fertilizer with simultaneous production of biogas with a net caloric value from 21 to 23 MJ/m3. Analyses in Poland indicate that after the introduction of world prices for natural gas, the production of biogas will be fully profitable. Biogas production potential in Poland is estimated at 5-6 billion m3/year.
During recent years, a rather rapid development of installations utilizing geothermal energy for generating electric energy and heat energy in particular has occurred. The thermal energy of geothermal waters and also that of dry rocks originates from the energy of the heat stream of the earth, which constitutes the heat coming from the depth of the earth and the heat that is generated in the lithosphere. The earth is also heated by solar radiation. For geothermal purposes the zones of the earth with anomalously high temperatures are used. Traditionally, they are volcanic zones with superheated steam or with very hot water, which are used for electric energy generation. However, recently lower temperature sources in the range of 50-100 C have been developed for heating purposes in Italy, France, Hungary, the former Soviet Union, Japan, the U.S., the Philippines, New Zealand, and China.
As the geothermal waters are usually mineralized, the modern technologies of their use require forcing the cooled waters back into the rock mass after the heat has been extracted by heat exchangers. Geothermal energy is of local character but it can cover whole regions where numerous installations can operate. It is ecologically pure energy and can be utilized in a very wide range of areas—from district heating to recreation and agriculture. Geothermal energy resources are estimated in Poland to be significant, especially in the southern part of the country. Geothermal waters with a temperature below 70 C can be utilized in winter for heating when combined with electric energy or natural gas in ways that might substantially improve the natural environment by reducing air pollution from coal burning.
At present in Poland, a pilot 1.5 MW geothermal installation is being built in the sub-Carpathian region. The method of intrinsic flow to the rock mass of cooled water without the use of pumps has been worked out. The power of this installation can be raised to 11.8 MW by means of utilizing pumps and extracting heat from the water by cooling from the temperature of 86 C to 35 C.
This paper has reviewed the potential for renewable energy development in Poland. Development and utilization of renewable energy will proceed with the improvement of technological processes in which this energy is generated and with the growth of ecological consciousness of the people.