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Vlasta PETŘÍKOVÁ

Utilization of Plant Materials as an Energy Source.

International Conference in Warsaw 29.-30. Sep. 1998

Demands for the consumption of energy still increase and then cause always more extensive problems. Exclusive and intensive utilization of fossil sources is for sustainable development of ecology already impossible. This problem acquires whole world dimensions, therefore the serious dealing is necessary.

To mobilize all renewable sources of energy, e.g. only in Europe, is not easy neither for member states of EC and nor yet either for non-member states, as is e.g. the Czech Republic. Therefore we welcomed the establishment of the association of european states called AE Biom, which associates not only the states of EC, but also the states of central and east Europe. Incorporation of Czech association CZ Biom into the european Biom was successfully accomplished already in 1995. Our membership enable us to obtain the contacts and information about the activities from the states, which have long-term experiences with the phytoenergy programme, which we would like to take over and apply in our country.

Putting through the energy from biomass is not easy, particularly as regards the individual approach. Therefore AE Biom struggle to progress coordinatively and work together as much as possible in all states of association. Important activity consists also in working-out of the materials of European energetic policy. The example from last weeks is the “Statement on the White Paper”. To reach the particular aims contained in this well known energetic programme of Europe, it’s necessary to arrange for the number of concrete conditions. AE Biom in its “Statement” formulated the conditions into the following points :

1. Establish the national programmes of the development of renewable energy sources in each particular state.
2. Cost of electricity from biomass include into the energy market.
3. Include the programme of the production of technical and energetic plants into the agricultural politics as a source of renewable raw materials.
4. Create new financial fund for the renewable energy sources - till 2010 it is necessary to invest 165 milliards ECU
5. Introduce the energetic taxes - 260 ECU / t of oil equivalent. Deal with renewable energy sources without taxes.
6. Support the research, development and demonstration projects in maximum extent.
7. Propagation of renewable energy sources, arrange for the acquaintance for broad public.

The implementation of this programme, according the analysis of AE Biom, has to begin no later than in 2000, otherwise there will not be possible to meet the aims contained in “White Paper”. To reach the principles mentioned above will be very hard particularly for the Czech Republic, because contemporary share of energy sources from biomass is on the lowest level in Europe. This follows from the latest investigation of AE Biom in 1997 considering 12 associated states and it is clearly evident from the following survey.

Share of energy from biomass in %:

From the survey is also evident, how different is share of energy from biomass in individual states. The highest share have the scandinavian states and Austria. This is the consequence of high share of forests in these states, from which all forest waste is utilized. In our conditions is also important considerable potential of forest and wood wastes, but to the purpose of phytoenergetic is used only the traditional firing wood as a rule. Only sporadically, the wood waste is chipped and combusted in a few heating plants.

Sources of plant materials for the utilization in energetics are diversed. On principle, they can be divided into 2 groups :

• waste materials or by-products
• purposively cultivated plants or fast rotation coppice

It is understandable, that by-products or waste materials are more effective, because the expenses for their production are included especially into main product. In agriculture, the cereal and rape straw is such example, further more the shoots after the harvest of maize (corn), stem of sunflower after the harvest in full maturity and many other wastes from different plants. These straw materials are processed by pressing into the large bales. Forest and wood waste is processed for direct combustion by chipping or pressing into the briquettes or pellets. Expenses for the utilization of wastes or by-products consist therefore only in their appropriate treatment and the transport to the place of utilization.

For essential development of phytoenergetics is necessary to calculate also with the targeted cultivation of special technical plants. It is important not only for own arrangement of sufficient sources of fuels, but particularly for purposeful utilization of surplus of agricultural soil. In the conditions of Czech republic is estimated, that the surplus of agricultural soil is cca 500.000 ha. This soil is currently insufficiently cultivated, which causes considerable problems with the infestation with weeds and with compliance of cultural agricultural landscape. Utilization of this soil for the production of energetic plants would be indisputably advantageous. This production will not compete on the market with foods and particularly enable a large number of new work possibilities in rural region.

From the reasons mentioned above we have begun the systematic work in cultivation of non-traditional energetic plants. Already in 1990, we have started the cultivation of Miscanthus in the Research Institute of crop Production, Research Station Chomutov. The first seedlings we have imported from Germany, where this plant was highly recommended for energetic purposes in that time. Miscanthus is the plant of good growing capacity (even 4 m high grass), on the stand persist in average 20 years. Roughly, after 3 years from planting, this plant gives every year high yields of dry matter, cca 20 t from 1 ha. But in the Chomutov region, this plant did not prove well, because it needs sufficient amount of humidity in the vegetation period and soft winter conditions. The plants mostly froze out. Although in some other areas of Czech Republic the cultivation of Miscanthus was more successful, it cannot be unambiguously recommended particularly for its high expenses of the plantation establishment. This is also the cause, that either in Germany, there are not established large cultivation areas so far, although there are the excellent growths on trial plots.

For our conditions is therefore necessary to find out the other suitable plants. For the direct combustion are prospective highly growing robust plants, creating large amount of shoots. Many of them are used, or previously were used as a fodder crops for feed-stuffs purposes, but number of them are untraditional plants, not very well known in our country. The question are annual, multiannual and perennial plants, which are more effective for these purposes than annual plants, demanding for the repeated cultivation in growth establishment.

As regards the annual plants, we deal with the plants of C4 type, as is e.g. Sorghum saccharatum, Sorghum vulgare, Sorghum sudanense, Hyso, but also Cannabis sativa and the others. Recently, we have begun to test new species of highly growing perennial plants. As a very prospective there is e.g. fodder sorrel (hybride of Rumex patientia and Rumex tianshanicus), folowed by Malva meluca, Sylphium perfoliatum and others, as stated in table 1. There is stated also the energetic yield in the form of combustion heat.

Table 1.: The yields of dry matter in t/ha and combustion heat (average from different stands):

Malva meluca is, in the table above, classified among perennial plants, although this is the annual plant. It is therefore, that in full maturity always the part of fruits drop seeds and next year in general create repeatedly fully incorporated growth. Malva meluca is also highly growing, it reaches from 1,5 to 2 m height. It can be used eventually also as a green fodder, or as the mass for the production of biogass. In this case it yields 2 cuttings in one year. For phytoenergy Malva meluca is the prospective plant, because reaches in good nutrition 10 - 15 t of dry matter from 1 ha. The importance of Malva meluca consists also in its very rapid springing up and soon coming of vegetation. By this is rapidly created continuous fully incorporated growth, which restrains the growing of weed. There was proven, also in running conditions, that it was effective explicitly as a biological weed preparation. Rapid coming of vegetation of Malva meluca predetermines this plant also for erosion stands, where is necessary to fixed the soil by means of plant roots. Therefore, Malva meluca can be also used as an antierosion precaution.

From perennial fodder plants, the highest yield was reached by fodder sorrel, which has also high fodder value. Besides the robust shoots which reach over 2 m height, sorrel creates the substantial amount of seed, which can be used partly as a solid fodder, or partly used as a seed for the establishment of new growths. It is harvested in full maturity from July to August, so that the seed will not be overraped and fall down. After the main harvest the fodder sorrel became getting covered with dense overground leaves, which can be used in autumn, in the case of need, as a green fodder. If there is not the necessity to use it up as a fodder, the leaves remain on the stand and sorrel in the spring repeatedly rapidly grow up.

The other perrenial plant suitable for phytoenergy is Sylphium perfoliatum. It is robust plant, which reaches from 1,6 to 1,8 m of height. On the stands persists as late as 20 years in full vegetation. It has robust stalk with relative broad leaves. The seed rapes in September as a rule. For the phytoenergetic purposes it can be harvested only after the drying up, eventually after the dropping leaves, in the interest of obtaining as much as possible dry matter, that is cca in October.

Also Echinops ritro is perennial plant, it grows to 1 - 1,5 m of height. It is some type of ornamental plant, very often become wild. It has solid, easily drying stalk, so that it can be satisfactory used for energetic purposes in direct combustion. It’s cultivation technology will be necessary to prove in operation conditions, because the cultivation for ornamental purposes has not so far the character of areal business cultivation. But in the trial conditions this plant proved well, therefore it’s cultivation in large scale would be useful.

From wild species of lants, as regards the creation of yields and then also the energetic contents, is Reynoutria sachalinensis the best unrivalled plant. But it is expansive plant, so that it’s spreading is not desirable. Therefore, it’s man-made established growth we carefully observed from the point of it’s expansion into the surrounding space. In the course of recent vegetation - more than 5 years - we have not mentioned the “getaway” of new plants from separate space. It is also possible by particular vegetation spreading of Reynoutria, by underground roots, while the spreading by seed is very limited. Coming of flower is later in general and the seed mostly does not ripen. It is interesting, that e.g. in Germany, the expansion of Reynoutria is not considered to be dangerous, because it is used as a hyperacumulator for uptake of heavy metals from contaminated soil there, and one seedling is sold out for 5 DEM. It’s understandable, that it is necessary to protect the nature against expansive species. But wildly growing Reynoutria is in some localities spreaded so much, that it makes almost continuous growth. If these stands are available for mechanization harvest, it would be indisputably useful these growths harvested for the phytoenergetic purposes. The regular harvest of these growths would reduce step by step these localities, because the nutrients of withered plants would be removed from the stand. This way of utilization of Reynoutria would even help with it’s desirable liquidation then.

In the table 1 are also the data about the creation of matter and the energetic yield of wood species - Ailanthus glandulosa. We have included this plant into the trial plot for it’s very rapid getting covered with leaves and absolutely minimum demands for the stand. Ailanthus glandulosa can be established from the seed, what is also very interesting from the economic point of view. It is indisputabely significant difference in expenses of the plantation sowing e.g. of fast rotation coppice. Although, the question is predominantly the seedling from cuttings, the expenses are more higher, than if the growth is established by simple sowing of seed. From the phytoenergetics point of view, the Ailanthus glandulosa is advantageous also by it’s very rapid increase of matter, so that it can be harvested even every year. Like the Reynoutria, the Ailanthus glandulosa is also expansive species, so that in the case of it’s intentional cultivation it is necessary to care about appropriate principles of the nature protection.

To the purposes of obtaining the biomass for energy it is generally recommended the establishing of plantations of fast rotation coppice, particularly the poplars and willows, as already mentioned above. The rich experiences with the cultivation of these woods have people e.g. in Scandinavia and in Austria, but also in a number of the other states. Also in our country we have become to establish these growths in large scale. Considering the high expenses for the establishing of these plantations, it’s extent is not sufficient so far.

The cultivation of energetic plants enable fully new, non-traditional way of utilization of surplus agricultural soil. Besides the traditional agricultural soil, we have in our country also the other large land areas. The question is the space after the recultivation of the areas devastated by industry, particularly by the mine and energetic activity. Utilization of this land for the cultivation of these energetic plants is very suitable. Already today, it is not necessary, at all cost, to recultivate these land to regular agricultural soil as it was in the past. The cultivation of technical non-food crops on these areas is advantageous also from the fact, that this area is in general affected by the imissions, so that it is not purposeful here to direct exclusively on the food production. On the basis of mentioned reasons we have fully directed to the cultivation of energetic plants on these lands, that is on mine dumps and power-plant ash deposits. Obtained results are very good, as follows also from the yields of dry matter, stated in table 2.

Besides the production obtained on these “anthropogenic” soils, there are also stated the yields obtained on traditional agricultural soil, in the same time period, as a average of 4 years.

Table 2. The yields of dry matter of technical plants in t/ha.

From the examples of selected plants follows, that anthropogenic soils are for their successful cultivation suitable as a agricultural soil. But the yields are a little different according the plant species. On the agricultural soil was obtained the highest production of dry matter by Hyso and Sorghum saccharatum and does not differ much from the average values of anthropogenic soils. On ash dump were the highest yields obtained by the cultivation of Sorghum saccharatum and on ash deposit by the cultivation of Cannabis sativa. These results can differ in individual years according the weather course. But it is decisive, that these high growing plants can be cultivated on recultivated areas as well as on the agricultural soil and so serve as a source of renewable energy.

Summary and conclusions

By the cultivation of plants for non-food and energetic purposes arises the new possibility of market production, which does not compete on the food market. This new programme - phytoenergetics - is interdisciplinar and have the importance not only for own agriculture in the utilization of surplus soil and new recultivated areas, but also for the other branches :

• energetics - source for renewable energies
• living environment - by the limiting of fossil fuels combustion and by the cultivation of extensive cultures has been contributed to the reduction of greenhouse gases and undesired imissions
• social area - the development of phytoenergetics will create a number of new working opportunities, especially in marginal rural regions, where is generally the highest unemployment.

Introducing of the phytoenergetics needs co-ordinated approach of all branches mentioned above and mutual connection of their activities. It is hard long-term work, but considering it’s importance, it is necessary already now to find out all possibilities, how this programme started in our country. In this direction we aim for the utilization of cooperation with the European association - AE Biom (by means of CZ Biom) and the experiences of highly developed european states, where the development of phytoenergetics is already on high level.