**8. Utilization**

288 Sustainable Growth and Applications in Renewable Energy Sources

*graminis*). Szarvasi-1 energy grass proved to be sensitive to mildew particularly on those sites where intensive growth of the plant occurred due to optimal nutrient and water availability. The mildew infection can cause severe damage on the leaf structure of the plant resulting in total devastation of whole patches. Proper chemical plant protection is needed to avoid significant biomass production loss. Infection of mildew was mediated by old hay bales deposited along the edge of energy grass fields, so the prompt collection and transportation of bales can contribute to lowering the chance of energy grass fields being reinfected. According to our results, chemical protection of energy grass fields must be taken

Ecological invasion of neophyte plant and animal taxa has now become one of the most feared sources of natural habitat degradation according to many nationwide and international surveys (e.g. Molnár et al., 2008) The most frequent method of neophyte introduction is their agricultural use through which their large-scale distribution and successful establishment are intensively supported by human activities. Suggesting new plant taxa to be involved in agricultural production bears the hazard of suggesting a new potential invasive plant too. Hence thorough investigation and consideration must be taken

*Elymus elongatus* is a rare, native plant species to Hungary; consequently its Szarvasi-1 cultivar is much more favourable for agricultural production in Hungary than other exotic biomass grasses. Szarvasi-1 carries genetic material that is derived from only indigenous populations of *E. elongatus* in Hungary. Hence the cultivar can be regarded as an indigenous taxon, so its potential as an ecological hazard in terms of invasivity is low. Since Szarvasi-1 energy grass has a transient seedbank type (i.e. its seeds lose their viability in a year), its cropfields can be transformed into any other crop without the problem of resprouting. High competitive ability as well as fast growth dynamics are the main characters of Szarvasi-1 energy grass when it manages to establish itself completely. As our experiments suggested, weed species can outcompete Szarvasi-1 energy grass individuals if there is only incomplete sprouting and the development of tillers are slow. In this case, the stands of Szarvasi-1 energy grass crop remain open, and weeds can gain a significant advantage in growing and spreading. This is why we expect Szarvasi-1 energy grass not to be able to invade intact natural or semi-natural habitats, not even in the close vicinity of energy grass fields from where the seeds can escape in large quantities. Energy grass can germinate only in anthropogenic habitats where continuous and intensive disturbance takes place (e.g. field margins, dirt roads and banks following man-made canals). Since energy grass cannot spread vegetatively (i.e. with rhizomes), it will not become such a hazardous invasive species as for instance *Solidago gigantea* or *Reynoutria japonica*, at least not in its native

For the rest of the world, it is worth being cautious. From Australia and the US the aggressive spread of energy grass has been reported (e.g. Cox, 2001; Walsh, 2008), where the plant formed homogeneous, closed stands outcompeting all the native elements of the local vegetation. Although this happened only in very close environments to the lands recultivated by *Elymus elongatus* (e.g. steep slopes and bank of canals), this might indicate the possibilities of its invasive spreading, particularly in those countries where natural

specialist herbivores, as well as pathogenic agents of *Elymus elongatus* are missing.

into account similarly to that in the case of any other traditional agricultural crops.

before introducing any new agricultural crop, especially a new biomass plant.

**7. Ecological hazard** 

habitat, in Eastern Europe.

The moisture content of the energy grass at harvest can highly influence the possibilities for storage, processing and utilization. Appropriate logistic and storage conditions can be provided by harvesting at the optimal time and the use of bales. In this manner the processing, chopping and direct energetic utilization of low moisture content of the baled fuel can be solved easily. High moisture content causes quality loss and negatively affects the processability and energetic characteristics of the material.

The application forms of energy grass used as fuel are:


The physical and some of the energetic characteristics of the listed fuel forms are different. The characteristics are summarized in Table 5.


\* values were determined based on the average of several measurements

Table 5. The physical and some of the energetic characteristics of the listed fuel assortment

Data show that independently of its form the energy grass has high ash content. It is necessary to mention however that based on technological and laboratorial investigations we have found that the high ash content is mainly caused by external physical contaminants. This can be significantly reduced e.g. by training the operators in maintaining technological discipline and by using the appropriate harvest-, loading-, and storing processes of the raw material. The elemental compositions of the investigated fuels are also different from the ligneous fuels. Chlorine and sulphur content were investigated by CHNS analysis which shows several times higher values compared to premium quality fuels (according to standards). This factor must be considered for energetic utilization. Herbaceous fuels (such as the energy grass) have low ash melting point, which greatly restricts their energetic utilization. The results, which clearly show the change in amount of ash sample plotted against temperature for ligneous and herbaceous fuels, are summarized in Fig. 17. Based on the results of the measurements it can be stated that the ash melting point of the energy grass is 690 C, while the ash melting point of the mixed wood-pellet is 1080 C.

Tall Wheatgrass Cultivar Szarvasi–1 (*Elymus elongatus* subsp. *ponticus* cv. Szarvasi–1)

duct.

systems.

**9. Conclusion** 

of the plant.

emission of solid component from boilers.

Szarvasi-1 in the course of annual growth (Fig. 18.).

as a Potential Energy Crop for Semi-Arid Lands of Eastern Europe 291

equipped with "travelling grates" which have a ladder-like structure and consist of more segments. There is another grate, so-called "crawler grate", which was named after its appearance because it resembles a looped ribbon stick. The heat and power plant boiler designs have several solutions. Utilization of the energy grass in coal power-plants was carried out with co-firing which can solve the problem of ash melting. During the combustion of herbaceous fuels higher solid emissions can be measured which mainly deposit in the boiler and exhaust with the flue gas. *The efficiency is highly damaged by deposition on the heat transfer surfaces, and* depending on the composition it can result in corrosive effects in the boiler. In order to prevent this, mechanical or pneumatic equipment should be installed with a dust separator, which cleans automatically the flue

Parallel with this solution it is necessary to reduce the load of solid components of the flue gas, the equipment is usually mounted with cyclone, which allays larger floating particles from flue gas. Electrostatic filter may also be assessed, which significantly reduces the

Another possible method for the energetic utilization of energy grass is the so-called pyrolytic procedure where the fuel is fumigated in a multistage process in an oxygen-low environment. The resultant "grass-gas" will be burnt directly or after a cleaning procedure it will be suitable for use in gas engines for electricity production. Because of the high capital costs these technologies are primarily economical in the case of using high-performance equipment. As a conclusion, it can be stated that problems concerning the use of the herbaceous fuels - including energy grass - in low-and high-performance boilers, directly, or with co-firing technique have been solved. The conditions of the application are determined by the logistic aspects and the current production costs. In the current boiler engineering, considering technical, energetic, environmental and economic aspects, the herbaceous fuels and their boilers may play an important role in the medium power-level market of energy

A new energy crop (*Elymus elongatus* subsp. *ponticus* cv. Szarvasi-1, tall wheatgrass) has recently been introduced to cultivation in Hungary to provide biomass for solid biofuel energy production. The cultivar was developed in Hungary from a native population of *E. elongatus* subsp. *ponticus* for agronomic and energetic purposes. The main goal of our research was to investigate the performance of Szarvasi-1 energy grass under different growing conditions (e.g. soil types, nutrition supply). We focused on the ecological background, biomass yield, weed composition, morphology, ecophysiology and the genetics

The biomass yield of Szarvasi-1 energy grass depends mainly on the presence of macronutrients, soil texture and water availability of fields. Under typical soil nutrient conditions, precipitation has a considerable effect on biomass yield. Average yield of Szarvasi-1 energy grass is as much as 10-15 t DM ha-1 with great spatial and temporal variation depending on weather and habitat conditions. As part of an intensive agricultural management, the use of fertilizers can be a good solution when soil nutrients are inadequate. Nitrogen plays an important role in increasing biomass in any phenophases of

Fig. 17. Ash melting diagram of fuels

The high alkali content, which was adsorbed during the lifetime of the plant, causes the low ash melting point of the energy grass. This causes combustion problems because the ash melting occurs in the operating temperature of boiler. The material can melt and sick onto the surface of the structure elements of the boiler, and this will lead to interior depositions and permanent damage. To solve this problem, new boiler and grate types were developed. The part of the combustion chamber where the fuel burns in solid phase cannot reach high enough temperatures for the ash melting. Continuous movement of the fuel also helps to avoid scorification and interior depositions. Boiler technology was developed so that the fuel is moving on a moving grate in the boiler while the volatile component of the fuel is gasified between 150°C and 400°C**.** The charred roughage falls off the grate to the ash pit before the fuel would be able to reach the critical melting temperature (Fig. 17.). The volatile component is burnt in the second part of the boiler (the so-called post-combustor) where the temperature of the combustion chamber is approx. 800-900°C. The problem of ash melting was solved and sufficient burnout of the combustion gas was also ensured by this new technical solution. Based on this operating principle there are many structural solutions and performances available on the market.

The boilers, which are suitable for energetic utilization of the energy grass, can be ranked into three different groups based on their performance levels.


Due to their structure and size the low power equipments are mainly operated with pellet fuel. These automatic systems are suitable for the combustion of energy grass pellets with appropriate efficiency and low emission. The size of the boiler and the manufacturing cost are greatly increased by the necessary moving grate. These equipments are more robust than the prevalent wood-pellet boilers. Medium power equipments are primarily used in communal and social facilities, which are mainly operated using pellets. They are equipped with "travelling grates" which have a ladder-like structure and consist of more segments. There is another grate, so-called "crawler grate", which was named after its appearance because it resembles a looped ribbon stick. The heat and power plant boiler designs have several solutions. Utilization of the energy grass in coal power-plants was carried out with co-firing which can solve the problem of ash melting. During the combustion of herbaceous fuels higher solid emissions can be measured which mainly deposit in the boiler and exhaust with the flue gas. *The efficiency is highly damaged by deposition on the heat transfer surfaces, and* depending on the composition it can result in corrosive effects in the boiler. In order to prevent this, mechanical or pneumatic equipment should be installed with a dust separator, which cleans automatically the flue duct.

Parallel with this solution it is necessary to reduce the load of solid components of the flue gas, the equipment is usually mounted with cyclone, which allays larger floating particles from flue gas. Electrostatic filter may also be assessed, which significantly reduces the emission of solid component from boilers.

Another possible method for the energetic utilization of energy grass is the so-called pyrolytic procedure where the fuel is fumigated in a multistage process in an oxygen-low environment. The resultant "grass-gas" will be burnt directly or after a cleaning procedure it will be suitable for use in gas engines for electricity production. Because of the high capital costs these technologies are primarily economical in the case of using high-performance equipment. As a conclusion, it can be stated that problems concerning the use of the herbaceous fuels - including energy grass - in low-and high-performance boilers, directly, or with co-firing technique have been solved. The conditions of the application are determined by the logistic aspects and the current production costs. In the current boiler engineering, considering technical, energetic, environmental and economic aspects, the herbaceous fuels and their boilers may play an important role in the medium power-level market of energy systems.
