Energy crops are one of the best options for obtaining an acceptable amount of biomass per unit of area and time. Moreover, as a fuel, their biomass has certain advantages from an environmental perspective over other, conventional fuels. By conducting tests with energy crops we can gain an understanding of how different plant species adapt to different cultivation systems, identify their needs, production potential and chemical and energy-related characteristics, and find out how to optimize production costs in economic, energy-related and environmental terms.
- CEDER has irrigable agricultural land located in an area with a continental Mediterranean climate. It also has equipment for conducting fieldwork and for monitoring, measuring and recording data.
Pilot plants for biomass classification and particle size reduction
This set of pilot facilities incorporates a number of technologies focusing on the industrial-scale study of biomass particle separation and size reduction, ranging from crushing bulky materials (e.g. bales and trunks) to fine milling to produce sizes of less than one millimetre. The plants are equipped with slow-rotation mills, hammer mills, bladed mills and sieves (with one or more sieving stages), along with a dynamic separator for making very fine granulometric cuts.
- The crushing capacity for bulky material is 1,000 kg/h with output sizes of less than 30 mm. During fine milling, the particles can be reduced from 30 mm to less than 100 micrometres. Energy consumption and performance is evaluated for all of the processes involved.
Pilot drying plants
There are two pilot facilities that have been set up for the drying of biomass: a conventional rotary-drum dryer, and a hybrid solar dryer designed and patented by CEDER-CIEMAT. Although the technology for indirect drying through parallel flow in rotary dryers is well known within the industry, solar drying applications – assisted by low-temperature heat – have as yet made little impact on the market. Hybrid solar drying is mostly used in facilities that generate wet sludge, such as wastewater treatment plants.
- Rotary dryer: hourly evaporation capacity of between 150 and 300 kg of water
- Hybrid solar dryer: hourly evaporation capacity of between 30 and 60 kg of water.
- Variables for heat and electricity consumption can be obtained for both dryers.
Facilities and equipment for pelleting biomass
There are two facilities, both of which are equipped with KAHL flat-die technology. One of the facilities comprises a small, highly versatile and easy-to-handle press (20 to 40 kg/h), which is used for conducting rapid pelleting tests using small amounts of product. The other facility is larger and is equipped with a dosing and mixing line, and has a capacity of between 200 and 400 kg/h of pellets. These facilities make it possible to conduct research on the behaviour of biomass and mixtures and to obtain data on the energy consumption and performance of the pelleting process.
- KAHL 14-175 flat-die machine with dosing hopper and variable speed.
- Pelleting plant with KAHL 33-500 press equipped with a mixing and dosing system, with the option of adding steam and a cooling and bagging system.
Biomass harvesting and logistics equipment
There are several items of equipment, including a BIOBALER WB-5 harvesting and baling system driven by a VALTRA T194D tractor, adapted for forestry work; and a self-loading trailer equipped with a versatile crane for transporting up to 20 bales, along with wood chips or crushed/bundled biomass. This equipment enables the simultaneous clearing and baling of biomass from energy crops and typical scrubland plants such as cistus, heather, broom and gorse. Using these and other items of equipment, CEDER-CIEMAT has developed working methods designed to enhance the viability of using forest mass that is currently unmanaged and is at a high risk of severe forest fire, in light of the large amount of continuous biomass per hectare.
Harvesting and baling of biomass crops with BIOBALER WB-5
- 200 HP tractor.
- Maximum gradient of 25%.
- Copes with moderate levels of stoniness.
- Adaptations for the harvesting of difficult species such as Cistus ladanifer.
- Data-acquisition system: operating and biomass-related variables: fuel consumption, performance within a cleared area, bales collected (moisture content and weight), speed, time per bale, environmental variables (temperature, RH), and slope.
- The research that has been conducted since 2015 on different types of scrubland has made it possible to evaluate harvesting performances ranging from 1 to 3 t DM per productive hour, or from 0.2 to 0.6 ha per productive hour for cleared areas.