This is from 2008, but I think it warrants more attention.

Last year, the German Greens Party commissioned a report on the potential of biogas in Europe. The Öko-Instituts and the Institut für Energetik in Leipzig carried out a study on the potential of biomethane in Europe.  The study came to the startling conclusion that, if current production trends continue, all of Europe’s natural gas imports from Russia could be covered by locally produced biogas/biomethane within 20 years. Earlier, Ulrich Schmack, an energy advisor to the German government and manager of the world’s largest biogas firm, came to the same conclusion, even though his projection created some controversy.

The biogas/biomethane sector is booming in Germany, and has become the
continent’s fastest renewable energy sector. For example, market leader
Schmack Biogas recently received a $192 million investment to expand
its activities, which is one of last year’s largest renewable energy
deals.  The growing interest in the gaseous biofuel can be explained by
the fact that: (1) biomethane production can be decentralized
(producing the fuel closer to its end use); (2)  it is highly efficient
(yielding more than twice as much energy per area of energy crops than
ethanol from similar crops); (3) it can be obtained relatively easily
from a large variety of biomass resources (e.g., organic waste, manure,
dedicated energy crops); and (4) advances in biogas technology,
microbiology and crop engineering have made (and continue to make)
production even more efficient.

The EU currently imports some 40 percent of all its natural gas from
Russia. In 2030, this dependency will have increased to 60 percent (all
else equal). This outlook worries many, as it opens obvious questions
about energy security. Last year, gas disputes between Russia and
Belarus and the Ukraine, affected energy supplies to the EU. The
Leipzig report on biogas, entitled “Möglichkeiten einer europäischen
Biogaseinspeisungsstrategie” (“The opportunities of a European strategy
to feed biogas into the natural gas grid”) puts this geopolitical
question into an entirely different perspective.

The main findings of the study are:

•    Europe’s potential for the sustainable production of biomethane is
17.7 trillion cubic feet per year. This is roughly the total amount of
natural gas currently consumed by the entire European Union.

•    All EU’s natural gas needs for the medium-term future (2020) can
be met by biogas/biomethane.  All imports from Russia could be
replaced, while the excess can back out petroleum and coal.

•    The production of 17.7 Tcf of biomethane, fed into the grid, will
result in a reduction of 15 percent of Europe’s CO2 emissions. The
Kyoto protocol demands a reduction of 10%.

•    An efficient biomethane-feed-in strategy could be built around the
concept of “biogas corridors.”  Such corridors would consist of biomass
plantations established alongside the pipelines, so that the green gas
can be fed into Europe’s main natural gas grid without the need for new
pipelines and infrastructures.

•    A Europe-wide biomethane-feed-in strategy will result in the
creation of 2.7 million new jobs within the EU. Employment will be
generated mainly in agriculture and in the manufacture, construction
and management of biogas plants and biogas purification plants.

A major roadblock standing in the way of moving to a biomethane economy
for Germany is the fact that biomethane is too good for the country’s
natural gas pipeline system, i.e., its heating value exceeds the
Germany’s upper quality limit on gas (the only country in Europe to
have this restriction). The German Green Party and the country’s
environmentalists and farmers, therefore, are lobbying for a new law
that would allow producers to feed their superior, renewable and green
gas into the national pipelines.  The German government has now taken
the first steps towards crafting a ‘biogas feed-in law’ that would
allow pipeline operators to open their network for biomethane.

Source: -
http://www.ngvglobal.com/report-biomethane-could-replace-all-eu-natural-gas-imports-0110