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Agronomically, the benefits to a grower can be summarized as:

 

DONT COMPETE WITH FOOD

Crambe - utilities

Low input costs (fertilizer, sprays etc) compared with other crops

Lower water requirements compared to other cash

Effective break crop with advantages to the following crop

Short growing period (120 days)

No specialized farming equipment or processes are required

Potential to profitably establish, grow and harvest marginal or disused land

 

 

 

 

 

 

 

 

 

Tolerant of warm dry conditions - Does not tolerate a humid climate
Does not tolerates acid soil pH 6.0-7.5 (water) ideal.

Greenhouse gas emissions

 

Crambe

 

A comparison is made of biobased production on 1 ha Crambe yielding biodiesel from crambe oil, seed meal, lignocellulosis by-products with a reference situation producing the same amount of transport fuel, protein feed and energy as in the crambe production situation (Table 1).

 

 

 

Yield of crambe seed is assumed to be 4 t/ha, with 1 ton of oil, 1 ton of seed meal and 1 ton of seed hull and 1 ton of straw. CO2-emission for Crambe production chain includes energy costs of inputs of primary production (mainly fertiliser), CO2-equivalent emission of N2O, transport of seed to extraction plant (200 km return distance), biodiesel manufacture and sea transport to Rotterdam (13,000 km).

 

In order to yield the same output as the biobased production of 1 ha of Crambe (Table 1), the reference situation needs to produce 41.8 GJ transport fuel from fossil oil, 36 GJ of coal product (both delivered in Rotterdam), and 1 ton of seed meal imported into Mozambique.

 

The energy cost of the feed import has been conservatively estimated as the energy cost allocated in the Crambe production to the seed meal, but is probably higher in a dedicated feed crop (leading to a higher CO2 emission reduction for the Crambe situation).

 

The increase in land use with 1 ha of Crambe is only 0.75 ha as 1 ha of Crambe yields the equivalent of 0.25 ha of protein feed imported, which reduces the land use 'footprint' of Crambe (Table 2).

 

The CO2-emission reduction has been calculated for the initial period during which the amount of carbon stored in the soil changes and for an equilibrium situation in which the amount of carbon stored has become stable.

 

 

Table 2. Land Use and C-stock effects on CO2 reduction emission for Crambe

 

The energy balance (amount of renewable energy produced minus the energy input in the biobased system - to be assumed to come from fossil energy sources) does not depend on whether such changes in the soil organic carbon are taken into account. The Crambe biobased production yields a gross energy of 76.8 GJ/ha/year with a (fossil fuel) energy input of 26.6 GJ/ha/year.

 

The energy content of fossil oil raw material to produce the needed fossil fuel is assumed to be 1.1 times the needed fossil fuel due to the fossil oil cost for the energy of fossil oil raw material production, transport and refinery/conversion to fossil fuel (in literature a range of the cost from fossil raw oil to fuel of 5 to 15 % is indicated).

 

As the renewable energy is used, the Crambe production has a net negative energy balance of about 30 GJ/ha/year, which is 67 % lower than in the reference situation.

 

Possible changes in carbon stored in and on the soil have a marked effect on the CO2-balance. It is the intention to use unused pastures in areas where hardly any animal husbandry is possible (due to tsetse fly). According to Laurijssen and Faaij (2009, Climatic Change, 94:287–317), the conversion of pastures to wood plantations or arable biobased crops leads to a decline in soil organic C during the first 20 years. Stubble and below ground production of Crambe is about 2 t/ha, of which is assumed 50% to be mineralised. The remainder yields an increase in the amount of carbon stored in the soil and on the land. As during the first 20 years, an increase in soil carbon occurs when changing from pastures to Crambe production, the CO2-emission reduction of the Crambe production chain versus the reference is higher when the change in soil carbon is taken into account (75 % reduction in CO2-equivalents emission) than for the equilibrium situation. Still, the CO2-emission reduction for the equilibrium situation is 69 %.

 

These values are high compared to values known for other oil seed crops like rape. In part this is caused by the higher by-product yield of crambe. It is assumed that Crambe seed hull and part of the straw can be used to replace coal (e.g. in co-firing for electricity or to produce biogas). Compared to the reference situation, it is assumed that coal is replaced and coal has a rather high CO2-emission per unit of energy produced.

 

Taking only the biodiesel of Crambe into account (with allocation of energy costs on basis of the economic value of the different plant parts, the CO2-emission reduction is relatively considerably lower, but with proper use of the by-products the Crambe, the reduction of energy use from fossil oil and the CO2-emission reduction are both much higher than the required 35 % (criterion set by the European directives on bio-energy and biofuels).

 

II. Analysis of effect on carbon balance of biobased production on 1 ha Eucalyptus compared with reference situation with only fossil energy sources

 

A comparison is made of biobased production on 1 ha Eucalyptus yielding wood pellets with a reference situation producing the same amount of energy as in the Eucalyptus production situation (Table 3).

 

Yield of Eucalyptus is assumed to be 7 t/ha per year on average. Potential yield of Eucalyptus under conditions not limited by water shortage is much higher (>12 t/ha per year). Using tree production models for rainfed conditions in Africa, Jongschaap (pers. comm.) has shown that 7 t/ha is a realistic yield for Eucalyptus.

 

 

Table 3. Base values for CO2 emission reduction calculations for reference and Eucalyptus

 

 

CO2-emission for the Eucalyptus production chain includes energy costs of inputs of primary production (mainly fertiliser), CO2-equivalent emission of N2O, transport of wood to a wood pellet installation (200 km return distance), conversion to wood pellet and sea transport to Rotterdam (13,000 km). The reference situation produces 75.6 GJ in coal product delivered at Rotterdam, to yield the same output as the biobased production of 1 ha of Eucalyptus.

 

The increase in land use with 1 ha of Eucalyptus is also 1 ha as no feed as by-product is produced (Table 4).

 

The CO2-emission reduction has been calculated for the initial period during which the amount of carbon stored in the soil changes and for an equilibrium situation in which the amount of carbon stored has become stable.

 

 

Table 4. Land Use and C-stock effects on CO2 reduction emission for Eucalyptus

 

 

The energy balance (amount of renewable energy produced minus the energy input in the biobased system - to be assumed to come from fossil energy sources) does not depend on whether such changes in the soil organic carbon are taken into account.

 

The Eucalyptus biobased production yields a gross energy of 75.6 GJ/ha/year with a (fossil fuel) energy input of 39.3 GJ/ha/year. The energy content of fossil oil raw material to produce the needed fossil fuel is assumed to be 1.1 times the needed fossil fuel due to the fossil oil cost for the energy of fossil oil raw material production, transport and refinery/conversion to fossil fuel (in literature a range of the cost from fossil raw oil to fuel of 5 to 15 % is indicated).

 

As the renewable energy is used, the Eucalyptus production has a net negative energy balance of about 44 GJ/ha/year, which is 47 % lower than in the reference situation.

 

The CO2-emission of the Eucalyptus production chain compared to the reference is 39 GJ/ha per year lower during the phase when the change in soil carbon is taken into account (80 % reduction in CO2-equivalents emission) than for the equilibrium situation. Still, the CO2-emission reduction for the equilibrium situation is 59 %.

 

Both in the calculations for Crambe and for Eucalyptus have a substantial degree of uncertainty, as especially uncertainty exists on the feasible production levels that can be obtained in Mozambique. It is an important purpose of this project to verify these production levels in practice. Attainable production levels will depend on rainfall, proper fertilisation and agricultural management.