WO2007000450A1

WO2007000450A1 - Process and plantation for the production of biomass and suitable harvesting machine

Info

Publication number: WO2007000450A1
Application number: PCT/EP2006/063582
Authority: WO
Inventors: Uwe Fischer
Original assignee: Fischer, Thomas, R.
Priority date: 2005-06-27
Filing date: 2006-06-27
Publication date: 2007-01-04
Also published as: DE102005029848A1

Abstract

Process for the production of biomass comprising the steps: a) planting of biomass-producing plants in several parallel rows with predetermined spacing between the plants, forming a row and the rows to one another; b) growing of the plants over a predetermined period; c) pruning of the plants in parallel rows, preferably in North-South direction, into a profile where the plants taper from a bottom area towards a top; and d) repeating steps 'b' and 'c' for recurrently harvesting the biomass.

Description

Process and Plantation for the Production of Biomass and Suitable Harvesting Machine

Technical Field

The invention relates to a process and a plantation for the production of biomass as well as to a harvesting machine designed to be used in connection with the process and plantation for that purpose.

Biomass represents an alternate source of primary energy that is especially advantageous with respect to renewability and environmental impact. In view of environmental protection and the expected exhaustion of fossil energy sources such as oil and natural gas and the problems arising from the distribution of those energy sources, renewable energy sources have gained an important role today and even more in the future. An additional use for biomass is the processing of raw material for the chemical industry.

Background Art

Methods for the production of biomass are known in a large-scale agricultural industrial manner. The production of wood chips, pellets and such from timber harvesting waste and other wood sources is well known and practised.

As a condition for the successful utilization of biomass as a large-scale significant primary source of energy is always the economical cultivation, harvest and processing. The economic efficiency of biomass production is determined largely by the cost of planting, cultivation and harvesting in both time and capital.

Disclosure of the Invention

The purpose of the invention is the creation of an economical process and an economically feasible plantation for the production of biomass as well as of a suitable harvesting machine therefore.

To fulfill the stated task the invention proposes a process according to claim 1, a plantation according to claim 7, and a harvesting machine according to claim 12. Preferred variations are stated in the dependent claims.

A new aspect of the plantation and of the process for the production of biomass according to the invention includes the repeated pruning with a particular profile in order to maximize the amount of biomass produced.

The plantation is intended to be used over a longer period of time to avoid the cost of repeated planting, to maximize the biomass production and to utilize the increased growth of the plants after an initial growing period. The repeated pruning during a year renders the process independent from the weather since the plantation can be harvested at any time.

Brief Description of the Drawings The invention is illustrated in the attached drawings and represents the preferred embodiments as shown:

Fig. 1 a top view of the placement of 4 plants indicating the spacing of the plants and the growth development within a plantation of the invention; Fig. 2 a side view of plant rows in a plantation with North-South orientation to illustrate the light angles during the course of the day;

Fig. 3 a side view of plant rows in a plantation with East-West orientation to illustrate the light angles during the course of a year;

Fig. 4 a section view of a plantation covering a base area of Im² ;

Fig. 5 a cross section of a plant row to illustrate the cutting depth and growth areas; Fig. 6 a side view of a harvesting machine for a plantation based on the invention; Fig. 7 a top view of a harvesting machine as in Fig. 6 and;

Fig. 8 a frontal view of the harvesting machine as in Fig. 6; Fig. 9 a top view of a plantation rail system layout whereas the distance in the North-South direction is longer than in the East-West direction;

Fig. 10 a detail of turntables used in the plantation rail system of Fig. 9; Fig. 11 a top view of a plantation rail system layout whereas the distance in the North-South direction is shorter than in the East-West direction;

Fig. 12 a detail of shunting system used in the plantation rail system of Fig. 11; and Fig. 13 a side view of a harvesting machine, attached trailer and second rail system for material transport and shunting of harvesting machine and trailer, including self- unloading ability as in Figs. 11 and 12.

Mode(s) for carrying out the Invention

The invention refers to a process or method for the production of biomass by means of an advantageous plantation and pruning of the plants or trees, which serve as source for the biomass, in order to increase the growth rate and thereby the yield of biomass per time unit. The invention refers especially to the use of trees, in this case especially cedars and particularly the "Western Red Cedar" or the Thujas, but can utilize other varieties with similar growth character with no or only slight modifications. Any plant species suitable for a long term mono culture to which the invention is directed should provide as many as possible of the following properties that support the economical use. A suitable plant species should: a) be highly resistant against vermin and diseases; b) tolerate repeated or multiple pruning; c) have high growth rates; d) have a growth structure that supports the harvesting, i.e. spreading branch and twig structure and high density; e) be reproducible by seeds and shoots; f) be adapted to the local climate and soil of the plantation - in addition the plantation should be adapted to the chosen plant in terms of irrigation, nutrient supply and supply of fertilizers; g) be reproduced from native plant varieties.

The above mentioned "Western Red Cedar" (Thuja plicata) or Thujas in general fulfil the properties a) to e) .

The choice of the plant species is determined by the new use and is additionally determined by the geographical location of the plantation. The economical parameters may also include and depend in part on the cost of the land - if the land is cheap plant species having a slower growth but being more suitably adapted to the climate may still be economical .

In order to produce the purest raw material with the lowest wood content the invention proposes to plant the saplings in long, parallel rows and to prune them in regular intervals. A careful planting will produce several advantages .

The plants are spaced preferably to a maximum density of 4 plants per m² , or a minimum distance of 0.5 m. from one another. During the first years of the plantation the young plants do not need to compete for the light and shading is a relatively small factor influencing growth rates. Only during the 3^rd and 4^th years (dependent upon the chosen plant species) will the plants spaced in such a fashion grow into one another, with shading becoming an increasing impediment (see Fig. 1) .

That is the reason the first pruning should proceed at this time.

The pruning should preferably be conducted in a North- South direction, as the resulting profile, where the width at the bottom of the plant in the East-West direction tapers towards the top, allows for equal sunlight exposure. This results in even growth that is a condition for an efficient mechanized harvest.

Since the North-South profile allows for an even light distribution throughout the day and since the angle of the sunlight constantly changes in an East-West direction, the noon sunlight is able to reach the lowest parts of the plants as well (see Fig. 2) .

The latitude of the plantation has therefore no or only minor influence on the even distribution of the daily light exposure.

With a height of 2 meters and a base of approximately 0.5 meters the North-South profile results in an angle of incidence of approximately 15°.

Depending on the time of year, the parts of the plant near the ground receive approximately one hour of direct sunlight during 12 hours of daylight increasing to 1.5 hours during 18 hours of daylight.

The upper portions of the plant receive direct sunlight during all the daylight hours gradually reducing the exposure time with decreasing height of the plant.

To some extent however, the thinner growth at the tips of the plant as well as some reflection allows additional light to reach the lower portions of the plant.

During pruning the parallel rows of plants are shortened to a height of between 1 meter to 2 meters, preferably 1.5 meters to 2 meters and further preferably to 1.5 meters and reduced to a width of the profile near the ground between 0.3 meter to 0.5 meter and preferably to 0.4 meter. The angle of the profile to the vertical is between 5 and 30 degrees, preferably between 5 and 15 degrees, and more preferably between 5 and 10 degrees.

The pruning in a direction other than North-South is possible, of course, even in the East-West direction, but compared to the North-South direction, it has the negative effect of increased shading of the plants, depending on the latitude of the plantation, and increasing with the distance from the equator. In the more northerly latitudes, direct sunlight reaches the lower ground level parts of the plants only for a short time during mid-summer. Before and after this time these parts of the plant, as well as the entire north side of the hedge profile are almost permanently shaded and growth is reduced (see Fig. 3). The shading causes a reduction of green growth and results in the creation of light-starved hollows and the formation of wood in the form of branches and stems . With the East-West profile the angle of incidence of the sunlight changes slowly during the course of the year. This means that the period of direct sunlight exposure during midsummer lasts from sunrise to sunset, but achieves this maximum for only a few weeks. The rest of the year, the north sides remain in permanent shade. Under these conditions, it will be difficult to shape the plants into the proposed profile, since most of the growth occurs in the tips of the plants causing rapid vertical growth at the expense of the lower parts of the plant. The advantages of a profile to increase surface area are therefore enhanced the more the North-South direction is a component of the plantation layout .

In order to utilize the acreage efficiently, it is necessary to reduce the hollow space caused by shading as much as possible. The North-South orientation of the hedge profile enables the entire surface of the profile to receive direct sunlight daily, independent of the season of the year, which produces even growth and reduces the unproductive hollow spaces and resulting lignification to a minimum. Depending on the species and the growth density of the plant the light penetration, enabling green growth reaches from 10- 30 cm deep. The profile of the hedge with North-South orientation, a maximum height of 2m and plant spacing of 4 plants per square meter achieves an eightfold increase in exposed surface area (see Fig 8) .

The optimum angle of the profile is determined by the light requirement of the chosen species and its growth characteristics. In order to facilitate a mechanical harvest, a species such as the "Western Red Cedar" for example, is preferred since it exhibits a strong, expansive drive toward the light and is therefore easier to prune than species such as "Thuja Pyramidalis . " This plant grows in the shape of a pyramid and has a tightly structured surface, which represents a disadvantage since it does not allow light to penetrate deeply and leads to a more difficulty mechanical pruning. The "Western Red Cedar" however, grows more open and faster, allows more light to penetrate, and results in a deeper green growth. This is an important attribute since it allows a relatively deep pruning cut while preserving enough green growth to ensure rapid continuous growth. Pruning the plants too deeply must be avoided as it leads to a reduction of growth (see Fig. 5) .

As a result of harvesting, the plants are reduced to a height of approximately 1.5 meters and a base of approximately 0.4 meters. This enables a higher light exposure with resulting higher growth rate than before the harvest. The pruning stimulates growth.

It is obvious that the harvesting method is most efficient the more hedge rows can be pruned simultaneously in one pass. The more flat and level the cultivated area, the easier it is to design equipment to permit the harvesting of a larger number of rows in a single pass. The harvesting machine must be able to bridge the maximum plant height of 2 meters before harvesting and of 1.5 meters after harvesting and to gather and transport the cut raw material efficiently. The larger the number of simultaneously harvested rows per pass, the less area needs to be provided for the transport routes and can be planted instead. A harvesting machine spanning 20 meters for example, with a plant spacing of 50cm can prune 40 rows simultaneously. In a preferred version, the harvesting machine should move on rails or tracks, allowing for a repeatable precision and requiring less attention by the operating personnel. The width of the track or rail system to be placed in the plantation is determined by the span of the harvesting machine; the further removal and transport of the material can be conducted via truck, conveyor belts or train, or a combination thereof, according to the economic situation encountered .

Figures 6, 7, and 8 depict a schematic representation of a harvesting machine according to the invention that is specifically suitable to be used in connection with the plantation and method of the invention, its pruning, gathering and removal of material. This harvesting machine must be able to complete several tasks. First, it has to be able to travel through the plantation repeatedly without harming the plants or their root system. Then, the cutting blades have to be able to produce the profile and a catchment device with attached transport equipment, i.e. conveyor belts have to be arranged in order to facilitate a rapid removal. In order to harvest several rows of plants simultaneously the cutting, gathering and transporting devices have to be duplicated for each row. In case the fields are not level, the harvesting machine should be able to keep the cutting and removal devices vertical, since the plants grow vertically.

The higher the numbers of rows harvested in one pass the more efficient the process. For a given area, fewer tracks or rails are required and less surface area is required for transport (conveyor belts, railways, roads) . It is also possible to operate several harvesting machines in a staggered formation permitting a further reduction of the unproductive area designated for transportation. In this case it would be possible to either widen and lengthen the conveyor belt that runs horizontally and perpendicular to the harvesting direction, or to increase the operating speed of the belt, since the harvesting volume is increased with each additional harvesting machine. The angle of the cutting blades should be adjustable in order to achieve the greatest flexibility in the creation of the profile. The gathering belt does not contact the ground, but floats closely above and is approximately 30 cm wide. At a plant spacing of 50 cm there will be 10 cm space remaining on either side of the belt. The harvesting machine has several cutting blades arranged side by side in the direction of movement, which cut the plants to the profile where the plants taper from the ground to the tops perpendicular to the direction of movement as shown in Figures 7 and 8.

The transport devices comprise several initial gathering or conveyor belts running in the travel direction and a second conveyor belt running perpendicular to the direction of travel, which connects to the first conveyor belts in order to move the biomass cut by the several blades to a centralized distribution point of the harvesting machine, where it is transferred to other means of transport. As described earlier, the North-South layout of the profile is crucial to high yields and determines the layout of the track network in the same direction. However, the shape of the plantation can vary considerably in terms of the alignment with that direction. For example, a plantation could be much longer in the North-South direction and much shorter in the East-West direction. In this case, the harvesting machine would most efficiently perform its task to harvest as many rows as possible in one long run. However, at the end of the rows the harvesting machine would either have to return to the beginning, move sideways and start a new set of rows or be able to turn around and return. On long runs an unproductive return could be avoided but the width of the harvesting machine would waste some plantation surface as the turning area would not be planted. This method of turning the harvesting machine for a continuous harvest can be justified only if these turns are not too frequent as the wasted area would accumulate.

As shown in Fig. 9, the plantation infrastructure has to include the transportation corridors to permit an unimpeded removal of the harvested biomass. These corridors are flanked by the rails of the harvesting machine. With the layout shown, it is possible to utilize the centre track of the planted area in both directions while the tracks bordering the corridors would be used only in one direction. The width of the transport corridor will be determined by the chosen system and its requirements. For example, a conveyer belt system requires very little width, whereas a conventional truck and trailer system would require more than double that. On the other hand, the capital investment needed to install a conveyer system is much greater. The specific economic situation will dictate that choice as these areas of the plantation which require space such as the turning radius and transport corridors have to be subtracted from the productive area (in the example given, a loss of approximately 25%) .

The turning of the harvesting machine requires two different designs due to the existence of the transport corridors (Fig. 10) . The first turn of the machine can be achieved by having a pivoting pin installed on the centre of the piece of track which extends beyond the end of the planted area and equals the length of the harvesting machine. The harvesting machine stops on the right (centre) track while the left side continues travel, rotating the track on the pivoting pin until the left side of the harvesting machine reaches and lines up with the next track, having completed a 180° turn. The harvester continues its travel in the opposite direction, but discharges the biomass into the next transport corridor. Coming to the end of the second plantation strip, the harvester can be turned to the right to repeat the last run or continue by turning left towards an unharvested plantation strip. This turn is more complex since the pivoting point has to be situated in the centre of the transport corridor in order to permit the lining up of the pivoting track extensions. When the 180° turn is completed, both tracks on either side of the corridor are aligned, allowing access to the lane. Simple turntables, as shown, one smaller turntable with the track mounted over the pivot pin, and one larger turntable with the pin centred between both tracks, will provide a low-cost solution. The travelling side of the harvesting machine does not require a track at this point but can roll on any hard surface as long as that surface has the same elevation as the rim of the harvester's wheel. These wheels should be able to swivel sufficiently to follow the required turning radius.

In the other scenario the plantation is shorter in the North-South direction and much wider in the East-West direction. In this case, the turn-around areas on both ends of the rows would have to be repeated many times and much field area would not find productive use. This area can only be reduced by reducing the width of the harvesting machine, thus requiring a shorter turning radius but increasing the number of tracks needed. The trade-offs and the final decision depend largely on the actual geographic situation of the plantation.

Shorter harvesting runs in the North-South direction would, from a certain point on, be conducted most efficiently by reversing the machine back to the start of the rows and moving sideways until it lines up with the next set of tracks to continue harvesting (Fig 11) . Because of the large number of short tracks, a sideways discharge can pose problems, as much surface area has to be devoted to transport systems. But, as the runs are short, the amount of collected material is limited. It is therefore recommended to utilize a second track-mounted vehicle identical to the harvesting machine, but without pruning shears or conveyer belts. Instead, this vehicle would function as a trailer, accepting the discharge of the cutters directly without use of an additional side- discharge conveyer belt. This trailer should have the ability to slowly distribute the biomass toward the rear of the trailer by means of a moving floor that will also facilitate the self-unloading after returning to the starting point. The capacity of the trailer should be equal to the quantities harvested in one run (Fig. 12) .

Since the loading capacity is determined by the large volume of the harvested biomass compared to its weight, the storage capacity could be increased by incorporating a first processing step of reducing the particle size of the biomass by means of a chipper/grinder mounted on either the harvester or trailer, thus enabling longer harvesting runs before needing to unload.

The required move sideways at the start of the rows can be accomplished very effectively by installing a set of tracks running East-West to utilize a train system to transport the biomass off the plantation to the next processing facility. This set of tracks would need to be lower than the North-South tracks of the harvesting machine and carry a cart which has track extensions mounted at the exact width as the harvesting machine, thus being able to first load the trailer, and subsequently the harvesting machine, and in reverse order, unload first the harvesting machine onto the next set of tracks, followed by the trailer to start a new run. Upon return the trailer unloads its cargo onto the transport system of choice (Fig. 13) . This system uses the land most efficiently, with only 5% of the area being wasted on transport.

It is clear that the layout and construction of the rail system represents a significant cost factor in the establishment of the plantation, even if it is a long-term investment. In addition to these costs, other important infrastructure must be provided in an attempt to maximize and optimize the operation. A plantation as densely planted as proposed will have high irrigation demands during dry periods if maximum growth rates are to be achieved. An effective irrigation system is a must as is an effective drainage system for the wet periods. Most plants do not do well in flooded conditions and it is recommended to prepare the plantation before any planting is conducted and to construct a system of cisterns and drainpipes feeding into them. During dry spells this collected water can be utilized while the improved drainage ensures high yields. As both the track system and the irrigation system are necessary to facilitate efficient biomass production and harvest, it is proposed to combine the functions into one and to construct a rail system out of hollow piping or tubing and to transport irrigation water through them and distribute throughout the plantation via low-pressure drip irrigation.

Industrial Applicability

The invention can be applied in the field of agricultural industry for the production of biomass to be utilized as a primary source of energy or processed in the chemical industry.

Claims

1. Process for the production of biomass comprising the steps : a) planting of biomass-producing plants in several parallel rows with predetermined spacing between the plants, forming a row and the rows to one another; b) growing of the plants over a predetermined period; c) pruning of the plants in parallel rows, preferably in North-South direction, into a profile where the plants taper from a bottom area towards a top; and d) repeating steps "b" and "c" for recurrently harvesting the biomass.

2. Process according to claim 1, wherein the distance between the plants forming a row and the rows beside one another is a minimum of 0.5 meters.

3. Process according to claim 1 or 2, whereas the plants are grown to a maximum height of 2 meters.

4. Process according to any one of claims 1 to 3, wherein the plants are pruned to a height between 1 and 2 meters, preferably between 1.5 to 2 meters and to a width of the profile bottom between 0.3 and 0.5 meters, preferably to 0.4 meters .

5. Process according to any one of claims 1 to 4, wherein the angle of the profile is between 5 and 30 degrees, preferably between 5 and 15 degrees, more preferably between 5 and 10 degrees from the vertical.

6. Process according to any one of claims 1 to 5, wherein the biomass-producing plant is a cedar, preferably a Western Red Cedar, or a Thuja.

7. Plantation for the production of biomass with: several parallel rows of biomass-producing plants, which were planted within a predetermined distance from one another, forming a row as well as the rows themselves, whereas the plants are pruned to a profile, which tapers from a bottom to a top, in parallel rows, preferably in a North- South direction.

8. Plantation according to claim 7, wherein the distance between the plants in a row, and the parallel rows, is a minimum of 0.5 meters.

9. Plantation according to claim 7 or 8 , wherein the plants have a height between 1 and 2 meters, preferably between 1.5 and 2 meters, and a bottom width of the profile of 0.3 to 0.6 meters, preferably between 0.4 to 0.5 meters.

10. Plantation according to any one of claims 7 to 9, wherein the angle of the profile is between 5 and 30 degrees, preferably between 5 and 15 degrees, more preferably between 5 and 10 degrees from the vertical.

11. Plantation according to any one of claims 7 to 10, wherein the biomass-producing plant is a cedar, preferably a Western Red Cedar or a Thuja.

12. Harvesting machine for the pruning of a plantation for the production of biomass according to any one of claims 7 to 11, including: several cutting devices placed beside one another in the direction of travel, which are able to prune a plant to a profile perpendicular to the direction of travel, tapering the plant from a bottom to a top, the cutting devices being connected to transport systems to convey the biomass, which is pruned by those cutting devices, towards a central discharge outlet of the harvesting machine.

13. The harvesting machine according to claim 12, wherein the transport system comprises several first-stage conveyor belts operating in the direction of travel and one secondary conveyor belt, operating perpendicular to the direction of travel .

14. The harvesting machine according to claim 12 or 13, wherein the machine operates on a rail system.

15. The harvesting machine according to claim 14, wherein the rail system is arranged to operate in North-South orientation, and incorporates turntable installations at a start and at an end of each plantation strip to facilitate the turning of the harvesting machine and to allow continuous harvesting without reversing.

16. The harvesting machine according to claim 15, wherein said rail system incorporates a second set of rails at the South or North end of the plantation to permit the shunting of the harvesting machine in an East-West direction utilizing a rail-car with track extensions mounted to accept at least the harvesting machine as a vehicle running on the rails.

17. The harvesting machine according to claim 12, further comprising a trailer for collecting the harvested biomass, said trailer being adapted to be attached to the harvesting machine and incorporates a moving floor for load-shifting and self-unloading ability.

18. The harvesting machine according to claim 17, wherein a chipper/grinder is incorporated in the harvesting stream to reduce volume of the biomass and increase storage capacity of the trailer.

19. The harvesting machine according to claim 14, 15, or 16, wherein the rails or tracks are made out of pipe or square tubing to permit the use of the rail system as part of an irrigation system.