biochar climate saving soils · · 2018-01-19feedstock entering the kiln must be a minimum of...

Biochar: climate saving soils – Newsletter 1 of 9

Newsletter 1 (December 2012)

BIOCHAR climate saving soils

The project Biochar: climate saving soils is a project which is

funded by the Interreg IVB North Sea Region Programme.

Partners from 7 countries share their biochar knowledge about

standards, production, use and environmental impact.

www.biochar-interreg4b.eu

Report Pyreg Tour (November 2012)

In November 2012 two members of the Interreg IVB Project

“Biochar: Climate Saving Soils” visited PYREG in Dörth,

Germany, and two operational PYREG units managed by

Swiss Biochar GmbH in Lausanne and by Verora GmbH in

Edlibach, Switzerland.

Pyreg GmbH is one of the leading technology development

companies in European pyrolysis. The company was

established in 2009 by chief engineer and CEO Helmut

Gerber, who began researching pyrolysis technology in

2004. Pyreg has developed what may be the closest thing

to a market-ready pyrolysis unit, capable of processing

diverse feedstocks, efficient heat recycling and producing a

consistent biochar product.

Two clients of the Pyreg GmbH have been very successful in

their respective countries. Gerald Dunst (Sonnenerde) won

the Austrian Climate Protection Prize in 2012. Verora GmbH

recently received additional funding from the Swiss Climate

Foundation.

Upcoming Events

February 14th and 15th 2013

2nd Nordic Biochar Seminar

(Helsinki)

March 12th and 13th 2013

Biochar: climate saving soils

project meeting (London)

March 14th and 15th 2013

Biochar COST action

meeting (London)

Text and photography by:

Jim Hammond

(UKBRC)

and

Jan-Markus Rödger

(HAWK)


The technology

The PYREG unit is a continuous screw-fed pyrolysis machine

capable of utilizing a diverse range of feedstocks at the rate

of a 100-150 kg dry matter per hour. The main unit, excluding

feed hopper, heat exchanger and feedstock drying systems

fits in a 20’ shipping container. The next generation of the

unit will be a 30’ container (including feed hopper and heat

exchanger). The unit must be initially fired using liquefied

petroleum gas (LPG) or natural gas (NG) but once up to

temperature the unit can run in a self-sustaining manner for

a period of many days. The longest continuous period

thoroughly trialed has been 14 days on, one day off for

cooling and cleaning, then on again for another 14 days.

That pattern has been trialed for a period of months.

Feedstock entering the kiln must be a minimum of 7MJ/kg

and 65% dry matter, or 15MJ/kg and 50% dry matter.

Feedstocks tested successfully to date include lop, brash,

woodchip screenings, miscanthus, willow, beet chip, spent

grains, pomace, colza cake, grain husks, coffee pulp,

digestate, biodegradable refuse, household waste, horse

dung, chicken litter, meat offal, sewage sludge paper fiber

and leather sludge.

Figure 1: Pyrolysis 500 Unit in Dörth, Germany

The equipment itself was fully functional on each of our visits. At

PYREG HQ in Dörth granulated and dried sewage sludge was

passing through the machine; and at Swiss biochar and Verora

the feedstock in use was woodchip screenings. Once the

parameters of the machine are set for a certain feedstock or

feedstock mix they need to be re-set for a different feedstock.

Partners:


Figure 2: Process image of the PYREG Unit (Source: PYREG GmbH)

Feedstock in the hopper is fed into the kiln by a rotary wheel sluice with metering device

attached. The rate of feed can be adjusted via the control panel. The feedstock drops into the

lower part of the kiln and is conveyed upwards and through by a screw-auger. The kilns are in

fact two twin units which operate in parallel. The biomass is fed through the central reactor of

the kilns, and hot gases flow (in the opposite direction) between the outer insulated jacket and

the central reactor. Whilst undergoing heating, the biomass releases flammable gases and

vapors which are drawn through a cyclone and into the combustion chamber. The

temperature of the gases leaving the reactor is measured and used as an indicator of reaction

temperature; typically between 450 and 800°C, depending on feedstock and process

parameters. The temperature in the combustion chamber where the flammable gases are

burned is usually above 1250°C. The hot exhaust gases from the combustion chamber then flow

back over the central reactor away from the main unit, leaving at approximately 500°C. At this

exit point from the main unit a heat exchanger can be fitted. Two different heat exchangers

(air-air and air-water) had been trialed successfully. The exhaust gases then flow through fans

(which provides the negative pressure for the system) and, if required, up through a chimney

for dispersion in the atmosphere. The main constituents of the exhaust gases are CO2 and

acidic steam neither of which are considered hazardous by the environmental regulators in

Germany or Switzerland provided that the feedstocks are not regulated as waste. The solid

phase of the biomass drops out of the top end of the kilns and is fed by another screw auger

through a water spray which wets the biochar to 30 % moisture content in order to avoid fire

risk, up another auger and into 1.3 m³ collection sacks.


Business Case: Verora, Edlibach, Switzerland

The business case of Verora is the simplest of those we visited. The Verora PYREG machine is

based at a cattle farm near to Edlibach, which is close to Zurich (CH). Verora, managed by

Fredy Abärcherli, produces wood chips for fuel use, biochar and high grade compost from

municipal and domestic tree waste and cattle manure. The tree waste (see Figure 3) is

separated into green material for composting, while the woody material is chipped. The

screenings (see Figure 4) from the woodchips are used to fuel the PYREG machine and to

produce the biochar.

Figure 3: Raw material for the business case of Verora GmbH.

Figure 4: Screenings of the woodchip production at Verora GmbH.


Figure 5: Pyrolysis unit at Verora GmbH.

Heat is harvested from the hot exhaust gases by an air-to-air heat exchanger house in a fifteen

meter pipe and a small shipping container for the fans. The exhaust gases are vented through

a chimney (approximately 4m high) and the hot air (40-70°C) is blown through a container filled

with woodchip (see Figure 6). After two days the woodchip are sufficiently dried at ready for

sale. There is additional capacity for another drying container to be fitted, and contract drying

work is sometimes carried out.

Figure 6: Thermal energy utilization in a 20’ container for drying of the woodchips. Air is blown through the

large pipes into the base of the containers at 40-70°C.

The compost operation is relatively small scale, processing 2500t of green material per year, but

produces a very high quality product retailing at 80 CHF (€65) per m3. Their compost is green

material mixed with cattle manure, turned daily or twice daily for the first four weeks and


composted for eight to ten weeks, the piles approximately 40cm tall (Figure 7). The operation

employs nine people.

Figure 7: 4 week old composting stacks with 10 % of biochar.

They have also developed a biochar compost (see Figure 8) retailing at 130 CHF per m3 (€105),

containing ten per cent by volume of biochar which is added into the compost mix from the

beginning of the process. Another option which Verora are exploring is the use of biochar as a

bedding additive to help soak up urine and reduce wetness under foot, which also as a route

into compost as the bedding material is added into the composting process.

Figure 8: Compost with 10 % of Biochar.

The biochar alone is sold for 340 CHF (€300) per m3; so far 60 m3 have been sold, with orders for

a further 30m3 on the books. The char is mainly being used as a cattle feed additive. Fredy

Abärcherli also runs a 130 member farming co-operative which shares equipment between

farms and has provided a market for Verora biochar. Mr. Abärcherli has worked for thirty years

in agricultural innovations. His most significant work was converting hundreds of farms to

horizontal rather than vertical silage storage.


Business Case: Swiss Biochar, Lausanne, Switzerland

Swiss Biochar is based at a large composting facility and cattle farm near to the beautiful city

of Lausanne, Switzerland. The biochar operation is managed by Hans-Pieter Schmidt, a leading

figure in both biochar research and practical application, and who has used PYREG

equipment since March 2010.

Figure 9: Composting site in Lausanne (CH) where Swiss Biochar has installed the PYREG-Unit.

The composting facility processes 35.000 t/yr of woody and green material and in this case

makes a low-grade compost which is given away for free (see Figure 9). The starting material is

green waste wood and trimmings from domestic, municipal and professional sources. Woody

material is separated and chipped, with screenings used to produce biochar. The compost

piles are approximately three meters high and are turned four times during the nine month

process.

Figure 10: Set-up of the Pyrolysis-unit at Swiss Biochar GmbH.


Swiss Biochar is investigating the ‘cascading use’ of biochar in the livestock sector. The

concept is that maximum benefit should be extracted from the biochar and its properties.

Whilst the ideas remain largely unproven in a scientific sense there is some published evidence

for some of the mechanisms at work and Swiss Biochar is confident in the trials they have

conducted themselves. The full use-chain proposed is as follows:

1.) Biochar may be mixed with silage during storage, taking up excess moisture thus reducing

mould or fungus growth.

2.) The silage is fed to cattle, who ingest the biochar. Biochar has been seen to provide some

previously unknown benefits to cattle digestion resulting in cattle putting on more weight, as

well as methane and nitrous oxide emissions reductions.

3.) The cattle pass on the biochar with their manure where it mixes with the other bedding

material. In manure, the biochar reduces nitrogen losses from volatilization of ammonium and

binds more ammonium and nitrates in the biochar itself.

4.) When the manure is spread onto the field, the biochar becomes incorporated into the soil,

already charged with nutrients and microbes, where it remains; hopefully to provide on-going

benefits to the plants growing in that soil.

Whether all these proposed benefits can be achieved and proven remains to be seen, but the

concept is certainly attractive. Local farmers have been convinced by the ‘feed additive’

idea. Ninety per cent of the biochar, produced by Swiss Biochar, is sold for this purpose. The

price is 340 CHF (€ 300) per m3.

Business Case: Sewage Sludge

At PYREG HQ in Dörth a new business model has been under serious investigation: the

conversion of sewage sludge into a phosphorous rich carbon-fertilizer. It is part of the

ClimaCarbo project which is led by Prof. Dr. Bruno Glaser at the Martin Luther University

Halle/Wittenberg. A new ruling in Germany means that there will be new strict limitations on

sewage sludge applications to agricultural lands starting at the beginning of 2014, so new

disposal routes for the material must be found.

PYREG receives the sludge mechanically dewatered, at about 25% dry matter. It is dried and

granulated in a modified container, built for this purpose, which uses two drying chambers of

different temperatures and is heated by the exhaust gas from the pyrolysis unit. Upon entering

the feedstock hopper, the sludge is at 70% dry matter. The processing of sewage sludge is

subject to waste regulation in Germany, which includes strict emission limits. Heavy metals from

the sludge leave in the gas phase, and are scrubbed out of the exhaust gas along with sulphur,

and the pH of the steam is raised, before it is emitted to the atmosphere. The biochar product is

20% carbon and 20% phosphorous by weight. PYREG is investigating the possibility to turn this

into a fertilizer product.


Future Plans of PYREG GmbH

PYREG is hopeful about the future. Contracts have recently been signed for four more PYREG

500 machines in Germany, and a large company has recently made substantial investments

permitting PYREG to expand their operations. They envisage that the PYREG 500 machine could

be used in most small towns, processing either woody wastes or sewage wastes, making use of

generated heat whilst improving soils and closing the loop on phosphorous losses via the

sewage system.

PYREG has also been experimenting with options for generating small amounts of electricity.

The most promising option is a hot air turbine, not much bigger than a bucket, developed at

the University of Langenbruck (CH). This turbine could be made to fit on the end of the exhaust

gas pipe and use the temperature differential to spin a turbine, generating approximately 9

kW. This would be more than enough to power the PYREG machine itself, with some additional

power left over. PYREG hopes to have the hot air turbine as a standard part of the machine

within the next year.

One problem we encountered during our visits was slagging due to liquid ashes in the

combustion chamber. These have to be removed regularly or the built up can damage the

machine. Even with regular cleaning the ashes can build up and cause problems. These type

of problems which occur during prolonged use are being ironed out by PYREG in collaboration

with their technology users.

The PYREG 500 costs about €300.000 plus possible costs for feedstock drying and handling

systems. Pyreg estimates that the full set-up to process sewage sludge would cost € 800.000.

PYREG is currently looking for business partners to use and demonstrate their equipment.

biochar climate saving soils · · 2018-01-19feedstock entering the kiln must be a minimum of...

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