Results of the project

Thermodynamics:

Lower electric energy process

Higher efficiency

Increase power output

Socio-environmental:

Renewable electricity or heat supply

In a sustainable management of a biogas plant and the

corresponding CHP unit it is crucial to keep the energy efficiency at

high level and to use all the produced heat and power. While

electricity can be sent to whatever place connected to the grid,

heat transmission if feasible only for short distances.

For this reason, finding a relevant heat receiver can make some

difficulties to plant operator. One of the not yet common solutions

is installation of an Organic Rankine Cycle (ORC) machine, which

converts unused heat into power.

Before 2012 Timo Wessels, operator the biogas plant in Trechwitz,

was releasing heat from CHP into the atmosphere. To change that

behavior he installed the ORC machine from ElectraTherm.

July 2013

Success Story

Operator: ElectraTherm, Inc. Location of the project : Trechwitz, Germany

Contact details:

Celeste Dodge Erlach

cdodge@electratherm.com

+1 775 398-4680

Heat-to-Power Application using a Dreyer & Bosse CHP power unit with an Internal Combustion Engine

Project outline

Picture: ORC Machine in Trechwitz - ElectraTherm

Performed actions

Biogas plant in Trechwitz produces gas form manure, maize and red

beets. Although the CHP is dimensioned for 800 KWel, plant is at

lower load and delivers 500 kWh of electricity. Thanks to inclusion

of the ElectraTherm’s machine, operated by etatherm, excess

engine heat can generare approx 7% more electricity. The ORC

power generation is based on a simple concept: hot water enters

the machine at 90-95°C, where it heats a working fluid into a

pressurized vapor. The high pressure vapor expands through

ElectraTherm’s patented twin screw power block, spinning an

electric generator rated for 30-65kWe output. After turning the twin

screw expander, the vapor is condensed back into a liquid through

the use of an external air cooled condenser. After condensing, the

working fluid flows back to the evaporator to repeat the process.

Results of performed service

Trechwitz biogas plant was the 5th one in Europe of its type and the

first one in Germany, which was meeting 60% of thermal

requirements to qualify for an extra bonus in frames of the German

Renewable Energy Law 2012 (EEG 2012). Since the installation the

operator produces 7% more electricity from the previously unused

heat and gains 7% more revenue. Thanks to the use of ORC concept

in a biogas plant and additional electricity can be produced without

any additional raw material or emissions.

European Biogas Association Rue d’Arlon 63-65

1040 Brussels, Belgium

+32 24 00 10 -87 or –88 info@european-biogas.eu www.european-biogas.eu

Technical data

Year of plant construction: 2012

Year of performed service:

2012 - today

Plant size: ORC machine: 35 kWe CHP: 500kWe MWM IC Engine

Process temperature: 90-95°C

Type of raw material: Manure, Maize, Red beets Heat utilization: 375-450 kWt

Prepared in collaboration with:

Picture: ElectraTherm