Posts Tagged ‘bioenergy’

Bioethanol – good or bad?

May 12, 2009

A study in USA shows that gasoline is better than ethanol from corn  (Science 1 May). Already this has caused headlines in daily papers. “Ethanol from agriculture is out”.

But the issue needs a second consideration. In this study it is presupposed that a reduction in food production needs compensation by turning grasslands and forests inte agricultural land. In the long run this is so, which has been previously discussed in this blogg (tag Climate). But let us widen the perspective. This way of accounting means a large secondary environmental load also for a more low-producing  organic agriculture.

Maybe it is more important to see a mosaic of opportunities. Bioethanol from agriculture can be an important forerunner for alternative fuels. But in the long run it seems necessary to use the arable land for efficient food production.

Advertisements

Biogas in Germany – a development with landscape consequences.

December 18, 2008

The development of biogas in Germany has a large support from the society. The process is so successful that it has changed the landscape in some regions. The former varying landscape with a diversity of crops has been changed to a landscape of maize.

Is that a development we want?

Swedish conditions for biogas are different, but it is important that wellmeaning support schemes don’t give unforeseen effects.

It has to be remembered that manure, which is seen as a substrate for biogas, has much lower energy value than the crops themselves

Bioenergy or soil carbon?

November 20, 2008

Biomass can be used for energy. It can also be returned to the soil where it would tend to increase the content of organic carbon. In the first case fossil fuel use is replaced, in the second carbon is stored so it will not contribute to emissions of carbon dioxide for a considerable time. Which way to prefer?

 

We consider one ton of dry biomass As bioenergy it may be worth 15 MJ per kilo. That means 15000 MJ which can replace 380 litres of oil and diminish carbon dioxide emissions by 1400 kg  carbon dioxide.

 

If instead we return the biomass (för instance straw) to the soil it will be decomposed and a part of it will become stable humus. One ton biomass contains about 400 kg carbon, and after the decomposition processes about 80 kg remains as stable soil organic carbon. This is equivalent to about 300 kg carbon dioxide.

 

Thus, as a climate measure it seems much more efficient to produce bioenergy. Now, there are energy expenses: harvesting, storage, transport and maybe processing. If the sum of these expenses are higher than 70 % of the original content, it would be better to return the biomass to the soil.

 

And there are further implications to consider. If soil organic matter is low the soil productivity may be impaired. Returning biomass may give advantages. For the individual farm of field suitable lines of action can be found.

Bioenergy in the USA.

October 10, 2008

Back to agriculture after the digress of yesterday.

 

About Bioenergy.

In Science 3 Oct (Policy Forum p 49) is a good summary from US horizon.

 

There is now a subsidy for cellulosic ethanol, $45 per ton of biomass to the grower and $1.01 per gallon to the refiner. But it is important that the whole system is sustainable and environmentally acceptable.

 

Cellulosic bioenergy may be the future, but it is not ready yet. Grain-based ethanol will be important in the near future.. In 2007 25% of US corn production was used for ethanol and the figure for 2008 will be about 30%. But it is stressed in the article that the current grain production creates important environmental problems.

 

But it is also stressed that improved practices can improve the situation:

No till farming

Advanced fertilizer technologies

Cover crops and riparian plantings.

 

This discussion seems familiar.

It should be important for Swedish Agriculture to continue the frontline development in this direction.

 

Have a look on previous contributions in this blog marked Focus Foresight.