Tuesday, September 20, 2011

899MW of newly approved biomass plants could increase carbon emissions

Last week DECC approved construction of a new 299MW biomass-burning plant owned by Anglesey Aluminium Metal Renewables. But new opinion from the Scientific Committee of the European Environment Agency (EEA) says plants like this will not be carbon-neutral and may even result in increased carbon emissions.

The proposed plant will employ up to 600 people during construction and around 100 full-time personnel when operational, and the company says its feedstock will be sourced from both imported and local sources - perhaps forests in Wales - with imports coming in through the Port of Holyhead.

This approach for sourcing fuel is identical to that being followed by Drax, which was given consent for 580MW of biomass-fuelled plant in the north-east six weeks ago.

Both are awaiting final go-ahead for construction when the results of the Government's review of the Renewable Obligation Certification (ROC) incentive scheme are announced, expected next month.

The EEA's report, however, says that biomass - fuels of plant origin like trees - should not be considered carbon neutral because this "fails to recognize that if bioenergy were not produced, land would typically grow plants anyway, and those plants would continue to absorb carbon and help to reduce carbon in the air".

The report calls it "double-counting to credit bioenergy for reducing carbon in the atmosphere through plant growth" because "plants would grow and absorb that carbon anyway".

The opinion derives from peer-reviewed articles published in Science magazine by a Princeton University researcher, Tim Searchinger.

The explanation for the opinion is given by a thought experiment: "imagine a hectare of cropland just abandoned and allowed to reforest. These growing plants would absorb carbon from the atmosphere into plant biomass." Some of that would be consumed and the carbon released by organisms into the atmosphere.

"Other carbon would be stored in vegetation and soils as the forest grows, and that ... would have the effect of offsetting some of the emissions of carbon by burning fossil fuels."

"However, if, instead of allowing the forest to grow, the land were used to grow energy crops which were burned in an electric power plant, their use would displace fossil fuel emissions, but the actual CO2 emitted by the power plant chimneys would not be reduced.

"Per unit of energy, the CO2 emissions would typically even be higher than those of a fossil fuel-burning power plant because biomass contains less energy per unit of carbon than petroleum products or natural gas and because biomass is usually burned with a lower efficiency than fossil fuels," the paper concludes.

In other words, using land to grow bioenergy crops sacrifices the use of the land to absorb and sequester carbon.

The CO2 released from the plant could only be counted as carbon-neutral if or when the carbon absorbed by the energy crops and burned in the power plant exceeded that which would otherwise be absorbed and sequestered by the growing forest.

This opinion has been questioned by Marlene Holzner, spokeswoman for EU Energy Commissioner Günther Oettinger, who cited another report compiled by Econometrica which says Searchinger did not compare CO2 emissions from biofuels to those from petrol.

The scientist himself has disagreed, saying,"The whole point of the analysis was to make that comparison – detail for detail. Biofuels will not reduce emissions, and may increase them."

Recent reports by the EU's Joint Research Centre JRC and the International Food Policy Research Institute (IFPRI) have also concluded that the burning of biofuels can increase CO2 output.

The EEA's opinion document does give examples of three scenarios where biofuels may reduce carbon emissions and not displace food crops:
  1. when bioenergy crops are planted on lands once covered with tropical forests that have been overrun by invasive grasses that frequently burn

  2. wastes that would otherwise be disposed of and allowed to decompose, emitting methane

  3. crop residues that would otherwise be burned. However, care must be taken to ensure that this loss of residues does not lead to reduced productivity and therefore reduced plant growth or reduced carbon sequestration in soils.

Furthermore, the document says that accounting must reflect any increases in GHG emission from fertiliser production required to replace the nutrients from the residues.

How does this affect the approved new UK biomass burning stations?

DECC's consenting letter says the plant may burn “biomass fuel feedstocks” that are defined as "fuel, excluding material which is, or is derived directly or indirectly from animal matter, which qualifies as 'biomass' under Article 4 of the Renewables Obligation Order 2009 (S.I. 2009 No. 785)".

This Article only defines biomass as material of which "at least 90 per cent of its energy content is derived...directly or indirectly from plant matter, animal matter, fungi or algae)".

This definition is incredibly broad. Therefore, in the absence of any other conditions, it is likely that timber from managed forests will be used as one of very few feedstocks that can be reliably and consistently sourced at the volume required by such large plants.

In this case, if Searchinger is right, overall carbon emissions resulting from the plants could well actually increase.

Anglesey Aluminium Metal Renewables is owned by Anglesey Aluminium Metal Ltd, which itself is jointly owned by Rio Tinto (51%) and Kaiser Aluminum & Chemical Corporation (49%).

No one from Anglesey Aluminium Metal Ltd was able to comment at this stage over the exact sources for the fuel for the proposed plants.

Anglesey Aluminium Metal used to run an aluminium smelting operation. This obtained its energy needs from the neighbouring old Wylfa Magnox nuclear power plants - two 490 MW reactors - Wales' only nuclear power plants, which are due for closure next near.

The smelting plant closed down itself on 30 September 2009 with the loss of many jobs.

But Wylfa is one of eight sites the Government considers suitable for future nuclear power stations. Horizon Nuclear Power, an E.ON and RWE joint venture, has said it intends to build about 3,000 MWe of new nuclear plant next to the old plants.

No comments: