Over 60% of the land in Ireland is covered by grass. The grass can be processed using a grass biorefinery providing low emission feed products for both ruminants and monogastrics contributing to Irish feed sufficiency and reduction of emissions associated with feed production

Grass Biorefinery


Biorefineries are innovative technologies, in which biomass such as grass and farm residuals can be co-processed to produce a variety of material and energy co-products (Sharma et al., 2011)

Grass biorefineries are also called green biorefineries because they use biomass which can be processed as a whole crop through multiple steps into different low/high value products.

Why should I consider grass biorefinery?

  • Grass biorefineries offer enormous potential for the diversification of farms through new business models, enabling the efficient production of new sustainable products
  • In grass biorefineries, grass can be fractionated into feeding components for ruminants and monogastric,  availing usable protein from grass.
  • This alternative protein feed source reduces the demand for soybeans as the only protein source thus  indirectly reducing CO2 emissions when forests are cleared for soybean production
  • The press cake fed to ruminants can be efficient in reducing rumen CH₄  and N2O resulting from ruminant excrement.

How does the biorefinery work? 

The video below shows the main steps in the grass biorefinery processing:

  1. Washing of grass: The grass is washed to remove sand and impurities
  2. Mechanical fractionation: This process produces press cake and a green juice
  3. Ensiling and Baling of press cake: The press cake is used as a high nitrogen efficiency feed with low emissions which can be used to feed ruminants
  4. Pressing, heat coagulation and filtration of protein juice: This green protein juice can be used directly as an input to wet feeding or dried to be accommodated as dry feed. This is used to feed monogastric animals including poultry and pigs (Stødkilde et al., 2021)

Economic and Environmental Benefits

Based on the previous research of Biorefinery Glas, the use of perennial grass for biorefinery was shown to offer environmental benefits.

  •  Presscake produced from perennial ryegrass delivered between 15% and 25% lower nitrogen emissions in excrement when compared with dairy cows fed with silage. In addition, in-vitro research using the Rusitec approach, showed a 15% reduction in rumen methane production when 66% of the silage was replaced with press cake.
  • During FZC, press cake trials, based on a ryegrass-clover mixture at a 60% replacement rate of silage with press cake delivered greater milk yield compared with cows fed with silage. Preliminary analysis indicates that the methane emissions per animal were also higher, but were lower when considered in the context of milk yield and FPCM.
  •  In addition to press cake, the biorefinery also brings benefits in terms of product displacement. Trials undertaken within FZC showed that the protein concentrate extracted from the grass was capable of replacing 50% of soybean meal in traditional weaner diets. 


Research at Farm Zero C

Work during Farm Zero C evaluated the production of rumen methane in cows fed with presscake and those on a control diet, using the GreenFeed methods. The results indicated that press cake drives dry matter intake, body weight, milk yield, milk solids yield, methane and carbon dioxide. However, the methane production for press cake cows (341g/day) was still lower than the national inventory prediction. Further trials took place to evaluate a higher inclusion rate of grass protein concentrate, aiming to displace soybean meal at 50% in the weaner diet. The results showed that the grass protein concentrate was a potential replacement for soya beans as performance of the pigs was found to be similar to those fed on a soya diet, and pigs on the treatment displayed a higher daily weight gain. These analyses were further incorporated into an LCA analysis for the farm and showed a significant reduction in carbon footprint where grass protein was used to replace 50% of soya. 

Other Research

Key findings from previous research are:

  • The press cake from the grass biorefinery could be used to feed cattle without reducing the performance of animals (Biorefinery Glas, 2020).
  • Excrement from cattle fed with press cake contained significantly reduced losses of nitrogen (15% lower)  and phosphorus (Biorefinery Glas, 2020; Piljman et al., 2018,). 
  • Pigs fed on a trial diet which had 27% of soyabean replaced by grass protein concentrates, ate well and gained more weight than those on the control diet (Ravindran et. al 2021).
  • Meat percentages of slaughter pigs increased linearly and displayed a higher fatty acid content with the inclusion of grass-clover protein in the feed (Stødkilde et al., 2021).

Links to more research

 Effect of feeding the grass fibrous fraction obtained from biorefinery on N and P utilization of dairy cows

Potential of press cake as a fodder source for dairy cows

Ensiled pulp from biorefining increased milk production in dairy cows compared with grass–clover silage

Pigs thrive on protein from clover grass


The biorefinery contributes to the following regulations and action plans.

Climate Action Plan 2021

Ag Climatise roadmap 2021 – The biorefinery contributes to the following key actions of the roadmap to climate

 “Action 7: Continue to invest in novel feed additives to reduce biogenic methane.”

“Action 8: increase the proportion of home-grown protein in livestock rations.”

“Action 12: Promote the development of a sustainable circular bio-economy within the agri-food sector.”

EU Protein Plan

EU Bio-economy Strategy


Currently, the following company supplies the biorefinery and products: