Autumn 2017 EN

Biogas Journal | Autumn_2017 English Issue
Transformer station in Cavillo in the state of Aquascalientes.
feed for its 250 cows on an area of 100 hectares. In
addition, there are energy cost savings of nearly 3,000
euros per year.
The farm uses biogas not only to heat the hot water for
cleaning the milking equipment, but also to run the motor
for the milking machine. Sistema Biobolsa
modified a Honda diesel motor so that it runs
on methane. The motor uses a V-belt to operate
the milking machine. But the V-belt can
also be transferred to a diesel motor if not
enough biogas is generated in the lagoon or
if the gas motor does not work for some other
reason.
Alex Eaton established Sistema Biobolsa initially
as a small NGO and then he converted it
into a company with headquarters in Mexico
City. Today, 45 people are employed at Sistema
Biobolsa. There are small subsidiaries
in Central American and soon in Kenya and
India. Sistema Biobolsa has already installed
more than 3,000 plants in Mexico. They
range from 4 to 280 cubic metres in size. As
modules, they can be combined. For the most
part, they consist of small household plants
used by families for cooking.
In Mexico, small farmers also have a particularly
difficult time with low milk prices. Saving
even just 30 euros for natural gas per month is a
great help. Furthermore, small farmers can pasteurize
their milk inexpensively with biogas, making it easier
to market it directly. Sistema Biobolsa has built about
100 larger plants. The methane from these plants is
used to heat piglet enclosures, in cheese factories and
to run milk machines such as those at Rancho Sinai.
The early morning fog drifting over the fields dissipates
slowly. You could almost believe you were in Schleswig-
Holstein in northern Germany. This elevation of this
area around Zumpango de Ocampo is just about 2,300
metres, which means low temperatures at night. For
this reason, the plant’s methane yield fluctuates between
60 and 100 cubic metres per day,
depending on the season and the weather.
“Lagoons are inexpensive, but they are also
like black boxes that are difficult to check”,
says Violeta Bravo de Sepúlveda. “Many
function poorly or not at all and are not able
to harvest the existing methane potential
from the substrates”, she continues.
A scientist, Violeta Bravo de Sepúlveda
is from Mexico; she completed studies in
Germany and is working for a project of
the Brandenburg University of Technology
(BTU) Cottbus-Senftenberg and the Center
of Research and Technologic Development
in Electrochemistry (CIDETEQ) in Querétaro,
Mexico, an important industrial location
in the state of the same name.
For example, together with poultry producer Pilgrims
Pride, she operated a pilot plant for treating wastewater.
Pilgrims Pride processes 300,000 chickens per
day. This generates 2,000 cubic metres of wastewater
full of grease and blood. For twelve years now, the company
has been fermenting the wastewater in lagoons
with a total volume of 46,000 cubic metres. It produces
6,000 cubic metres of methane per day. This is
enough to cover one-third of the process heat required
by the food production facility. Five steam engines generate
the heat. More is not possible because all of the
wastewater is in use. “They need a more efficient biogas
plant”.
Knowledge transfer from Cottbus
For this reason, on company grounds, Violeta Bravo de
Sepúlveda integrated and studied a 10 cubic metre
pilot reactor in actual plant operation. In contrast to
The biogas plant, 280
cubic metres in size,
is located at Rancho
Sinai near Zumpago de
Ocampo, northeast of
Mexico City.
33