Vall till etanolproduktion - koncept för vall i växtföljden

Abstract

This report is about ley for ethanol production, with focus on the cultivation and handling, and is part of the project " Biofuel from agricultural side streams and straw in a system perspective " financed by the Swedish Energy Agency. The project is a continuation of the issue of secure raw material supply from the EU project AGROinLOG, which is about producing ethanol from straw. In order to be cost effective, ethanol is usually produced in large-scale plants, and with straw as a feedstock a secure supply of large quantities of straw is required. Producing ethanol from ley broadens the raw material base and is an opportunity to secure the supply of raw materials, especially during years with low cereal yields or with difficult harvest conditions for the straw. Introducing ley to a cereal-dominated crop rotation gives many positive effects on the cultivation system and to subsequent crops. There need to be a market and a buyer of the crop for the grain producers to be interested in ley cultivation. This report focuses on how a concept for ley to ethanol could look from the farmer's perspective. One question in the project was if the choice of grass and legumes variety is important. Four varieties of grass, as well as red clover and alfalfa, were harvested and collected in the project, in pure stand from Lantmännen's variety trials in Lännäs and Svalöv. The interviews with farmers conducted in the project showed that nitrogen fixating legumes such as clover and alfalfa are interesting from a farmer’s perspective for the positive effects, they have on the cultivation system. They should preferably be cultivated in combination with a fast-growing grass variety. The analyses that were done to investigate how the different ley species work as substrates for ethanol and bio-oil production showed that all the tested varieties work in these processes. In order to supply an ethanol plant with substrate all year round, the possibility to deliver both fresh and ensiled grass was studied. Fresh ley can be supplied to the plant from late May to late October. Depending on the extent of the fresh ley supply, it is complemented with silage or straw to cover the daily feedstock need. In order to avoid losses and heating of the material before entering the plant, the fresh ley should be harvested continuously every or every second day. Also, the ley should be physically damaged or cut as little as possible during harvesting and handling. The harvesting of fresh grass can be done in two steps. First the grass is mowed and left in swaths on the field. After that a forage wagon picks up the ley followed by transport to the plant. The other option is a direct-harvesting system using a tractor with a direct cut forage wagon and a mower in the front. The grass is cut and directly put in the wagon for transport to the plant. Which system to choose depends on how much grass is to be delivered per occasion and what degree of damage to the structure that is desired before delivery. For the ensiled ley the same kind of large-scale, cost-effective harvesting system usually used for harvesting of ley for animal production is suggested, typically consisting of a mower followed by a self -propelled precision chopper with separate wagons for transport to the plant. Essentially, three actors are involved in the delivery of ley to the ethanol plant, the farmer, the ethanol producer and a contractor who performs one or more steps in the harvesting and handling chain. Depending on the interests and conditions of the actors, two alternatives can be used to describe who is doing what. In option 1, the farmer establishes the ley and sells it on root. Then it is the buyer, or a contractor hired by the buyer, who handles harvesting, transport and storage. Depending on conditions on farm and plant, storage can be done on farm, on an intermediate storage or on plant. Option 2 means that the farmer has a more active role in cultivation, harvesting and transport and delivers the ley to the plant, either fresh at harvest or ensiled during the rest of the year. Two alternative concepts have been identified for delivering ley to ethanol production, where the proximity to the ethanol plant is what distinguishes the concepts. The concept "close" is aimed at farms located a short distance from Agroetanol. Fresh ley grass can be delivered with tractor to the plant during the growing season and ensiled ley grass is delivered by truck from the farm. The short distance makes it more interesting to receive, primarily, liquid residual streams that are produced at the ethanol plant. For the farm "further away" it is primarily silage that can be delivered because the silage has a lower water content compared to fresh ley, which means that it has lower transport costs.Biodrivmedel från jordbrukets sidoströmmar och omväxlingsgrödor i ett systemperspekti