[Gasification] OT -- but interesting -- CNG for 3rd world

[Peter Singfield]

At 11:03 AM 6/11/2007 +0100, you wrote:
>On Sun, 10 Jun 2007 20:08:21 -0600 (CST), Peter Singfield wrote:
>
>>Remember -- compressing biomethane to 2000 PSI (actually -- they use 3000
>>PSI mostly these days) makes it really easy to seprate out the CO2 -- CO at t
>>liguifies -- methane does not!!) -
>
>CO2 does liquefy when pure but from what I can see even compressed to
>200bar the liquid phase is insignificant in mixture with methane as
>biogas at 30C. Even then the liquid portion is a mixture.
>
>AJH

When in doubt -- research!!

You created doubt -- so I researched this topic further.

Good goggle term is:

"purifying biomethane"

The best hit so far is this Url:

http://biopact.com/2007/03/questair-to-supply-biogas-purification.html

Appended is the text -- the answer appears to be "PSA"

And guess what folks -- biomethane is fast becoming as huge "NEW" enterprise!!

Next -- can one "PSA" at home??

Well --

"A compact biogas purification system like that of QuestAir, allows for a
decentralised production scenario that results in high quality gas, capable
of fuelling CNG-vehicles"

Dick -- this must make your heart beat faster ---

And also -- closing the circle:

"Meanwhile, German scientists are developing bio-based biogas purification
systems. They are looking into using micro-organisms and algae that feed on
the CO2 contained in biomethane. Pilot trials show this concept to hold
some promise"

Then feed back the algae back into the biomethane digester?? 


Peter

*****************Appended*************************

Monday, March 12, 2007

QuestAir to supply biogas purification systems to Swiss company 

Biogas holds a large potential to replace natural gas, both in Europe
(earlier post), as well as in the developing world.

The green, climate-neutral gas can be made efficiently from the anaerobic
fermentation of a wide variety of organic feedstocks, either derived from
dedicated bioenergy crops (earlier post on biogas maize, grasses and grass
hybrids)or from waste streams from agriculture, municipalities or industry.

An interesting development in the field of large-scale biogas production is
that of feeding the gas into the natural gas grid. In Europe, several
companies are already doing this (earlier post). In the same context, the
concept of 'biogas corridors' is gaining attention (earlier post). It
consists of the simple idea of establishing energy plantations and biogas
plants close to existing natural gas pipelines, which can then be supplied
with the green gas.

But for the idea to work, efficient biogas purification technologies must
be developed. Depending on the biomass feedstock, raw biogas has methane
concentrations of around 55 to 70%, with the remainder being carbon
dioxide, water, hydrogen sulfide and particulates. For it to be fed into
the natural gas grid, the biomethane must be scrubbed and reach methane
concentrations of more than 96%. Once the purified green gas is mixed into
the grid, end consumers of course do not note the difference, biogas can be
used just like its fossil counterpart: in power plants, by households, in
fuel cells or as a fuel for CNG-capable vehicles.

Several biogas purification technologies currently exist, with some
interesting innovations being made. One of the innovators is Canadian
company QuestAir Technologies Inc., which announced that it has received an
order for its compact M-3200 'Pressure Swing Adsorption' system to recover
pipeline grade methane from biogas generated by an anaerobic digester in
Lavigny, Switzerland.

This system, using an optimised pressure swing adsorption (PSA) process and
a proprietary rotary valve technology delivers a higher efficiency than
conventional PSA systems in a more compact, cost effective package.
QuestAir’s M-3200 system can upgrade up to 300,000 cubic feet (8500 cubic
meters) of biogas per day.

PSA is a commonly used technology for purifying gases. The technology was
introduced commercially in the 1960's and today PSA is used extensively in
the production and purification of oxygen, nitrogen and hydrogen for
industrial uses. PSA is based on the capacity of certain materials, such as
activated carbon and zeolites, to adsorb and desorb particular gases as the
gas pressure is raised and lowered. PSA can be used to separate a single
gas from a mixture of gases. A typical PSA system involves a cyclic process
where a number of connected vessels containing adsorbent material undergo
successive pressurization and depressurization steps in order to produce a
continuous stream of purified product gas.

The operation of a simplified PSA process to separate methane from a
feedstock gas containing impurities, such as carbon dioxide, carbon
monoxide or water is illustrated in the diagram (see diagram, click to
enlarge).

Conventional PSA systems used today in industry are made up of four to 16
large vessels, connected by a complex network of piping and valves to
switch the gas flows between the vessels. Despite their widespread use in
industry, QuestAir believes that large scale PSA systems suffer from a
number of inherent disadvantages. These PSA systems typically operate at
slow cycle speeds of 0.05-0.5 cycles/minute since faster cycle speeds would
cause the adsorbent beads to float or "fluidize" in the vessel, causing the
beads to wear and ultimately fail. To meet customer demands for capacity,
conventional PSA systems must utilize large vessels to compensate for the
slow cycle speeds, leading to higher costs and a large equipment footprint.
The use of large vessels also means that these PSA systems are typically
erected in the field, increasing installation costs. The network of piping
and valves used in large scale PSA systems, with the associated
instrumentation and process control equipment, also adds cost to the
overall system. QuestAir's simplified PSA system is far more compact,
modular and cost effective.

We focus on this technology, as it opens up very interesting opportunities
for decentralised bioenergy production in the developing world, even though
they are not to be realised in the immediate future:
 biomass :: bioenergy :: biofuels :: energy :: sustainability ::
purification ::biogas :: biomethane :: natural gas :: 

Many countries in the tropics and the subtropics have a large potential
both to recover biomethane from organic waste streams, especially in large
cities, as for its productio based on energy crops and agro-forestry residues.

A compact biogas purification system like that of QuestAir, allows for a
decentralised production scenario that results in high quality gas, capable
of fuelling CNG-vehicles.

Compared to other 'first generation' liquid biofuels, biogas production is
more energy efficient, it yields a greater amount of energy on a per
hectare basis. With a modular, portable purification system now available,
decentralised motor fuel production centres can be established in areas
previously unreachable by ordinary fossil fuels (such as oil and natural gas).

Such a decentralised system would side-step the need to extend natural gas
and oil pipeline grids, and instead could be established locally.
CNG-capable fleets can be introduced in remote locations, and bought off
the shelf without the need for modifications, as they would run on highly
purified biogas.

Alternatively, a scenario of biogas exports is not unthinkable. Several
liquefied natural gas (LNG) facilities are being build in the South
(notably in Equatorial Guinea, Nigeria and Angola) wich, just like the
existing ones (in Malaysia and Indonesia), could be supplied by purified
biogas. This green gas would then be fed into the LNG plant and be shipped
to world markets, where it would fetch premium prices because it is CO2
neutral and renewable.

Currently, the production costs implied under these scenarios are
prohibitive, but the concept as such is feasible. With technological
advances being made in the sector, which will result in steady decreases in
production costs, these scenarios will become practicable. Not in the least
given a future of 'peak oil and gas' and price-tags being put on carbon
dioxide.


It will be interesting to follow up on the Swiss case first, and see how it
develops. If successful, there is no reason for developing countries not to
adopt similar technologies.

QuestAir's purification system has been purchased by Verdesis Suisse SA as
part of a new plant that will recover methane from biogas generated by the
anaerobic digestion of organic wastes at the Lavigny site. The methane
recovery plant will be owned and operated Cosvegaz S.A., a Swiss gas
utility, and product methane from the plant will be injected into the local
natural gas distribution grid operated by Cosvegaz.

Jonathan Wilkinson, President and CEO of QuestAir said: “We are extremely
pleased to secure our first sale into the European biogas market, which
represents an exciting growth opportunity for QuestAir. We have seen
growing interest across the EU in the use of renewable sources of methane
to supplement or replace imported natural gas. In addition, government
programs in several EU countries are promoting the use of biogas as a
carbon neutral source of compressed natural gas (CNG) transportation fuel
for busses and cars.”

“QuestAir’s methane recovery systems offer a compact solution for
cost-effectively removing carbon dioxide and other impurities from biogas,
recovering high purity methane for high value end-uses,” Wilkinson said.


Meanwhile, German scientists are developing bio-based biogas purification
systems. They are looking into using micro-organisms and algae that feed on
the CO2 contained in biomethane. Pilot trials show this concept to hold
some promise (earlier post).



posted by Biopact team at 3:30 PM