Manure Treatment for Biofuel

Abstract

Animal excrements, such as manure, are by far the largest organic waste stream in the European Union. It is particularly large in the Netherlands where millions of animals per year are raised for meat, milk, eggs, gel, leather and many other products for daily consumption. As long as people consume such animal products, this production causes an unavoidable (wet) stream of organic matter containing various minerals. The question is, whether the material content of manure can be recycled, meaning all its main components reused as valuable products. In this chapter, we address the possibilities of separating and reusing these components. The focus is on cattle and pigs because most of the dry manure of chickens is already largely reused (mainly for energy production), and the manure volume of other animals is insignificant.

Appendix

Tables show options of manure processing and the typical cost of a CHP.

Economic parameters of (co-)digestion of manure and maize silage in different scenarios for the Dutch province of Overijssel (Vos and Zwart 2013)

Scenario	Biomass	Investment (€)	Specific investment (€/kW)	Profit per year (€)	Ratio cost to income
1,7 MWe	32,000 tons of ECN Mixa	4,712,055	2772	−922	2.2
Low price biomass	180,000 tons of fresh pig slurry	9,994,970	5879	−1,844,073	3.7
Scaling down (CHP)	5000 tons of fresh cattle manure	255,444	6904	−37,801	2.3
Scaling down (green gas)	5000 tons of fresh cattle manure	438,849	11,861	−59,303	4.4
Scaling up	100,000 tons of ECN mixa	15,961,652	3192	−3,036,324	2.2
Extra delivery of thermal energy (factor > 3)	32,000 tons of ECN mixa	4,821,714	2836	−761,632	1.8

1. ^aECN mix: 25% manure from own farm + 25% manure from elsewhere + 13% silage maize + 37% other co-substrate

Typical technical and financial parameters of a CHP-production in 2010; unit costs in eurocents per kWh (Rabo 2011)

Technical parameters	2010
CHP capacity (MWe)	1.5
Investments/MWe	2,900,000
Total running hours CHP for full for load per year	7300
kWh production/MWe CHP	7,300,000
% Energy use by the process	8.0
Net energy production kWh/MWe CHP	6,700,000
Economical parameters
Other incomesa	−0.2
Costs for co-products (Input + Output)	7.8
Maintenance costs	1.8
Labour/consultation/others	1.8
Depreciation and interest	5.3
Total costs	16.5
Cost price/kWh delivered on the energy grid	18

1. ^aNot including energy sales and subsidies (mostly thermal energy)