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Short-rotation Willow Biomass Plantations Irrigated and Fertilised with Wastewaters

3 Economical, legal and social aspects

3.1 Economical aspects

Two different economical studies were carried out relating to conditions in Northern Ireland. Sweden has been studied in this respect before (Rosenqvist, 1997; Rosenqvist et al., 1997). One of the studies concerned economical conditions for willow growing and business development of willow coppice production in general. The other study investigated the economy on willow irrigation with wastewater from a treatment plant. Where possible, comparisons were made with Swedish conditions.

The willow biomass industry in Northern Ireland is in a very early stage of development, imposing cost penalties on the pioneer growers. This situation could be compared with the situation in Sweden with an established industry based on at present 15 000 ha of willow plantations and where production costs are significantly lower.

To provide a positive return, according to the study, the price of willow chips must be at least £ 35/tonnes of dry matter (t DM). This figure does not include any opportunity cost for the land or any subsidy payment. From the model, it was estimated that a yield of 9.2 t DM/ha/y (from the second harvest cycle) was required to obtain a positive income from the land. Thus if the expected yield level was lower than 9.2 t DM/ha/y the land should be used for other purposes or be left fallow. For each increase in the number of harvesting cycles taken, the calculated gross margins will increase and production costs per t DM will decrease. A minimum of five rotations (16 years) would be required to attain a positive income from the land.

In Northern Ireland the average annual costs of growing willow biomass over a 22 year rotation were calculated to £ 349/ha or £ 35/t DM. Grain production and willow show a similar gross margin result. Willow was competitive when the grain prices were lower than £ 70 – £ 80/t. This study also shows that with gross margins, without the present subsidies for suckler cows of £ 200/ha and for lowland sheep of £ 234/ha, willow coppice can be competitive with other grassland-based enterprises, depending on the individual circumstances on each farm.

When the situation and costs for planting and harvesting willow in countries with different acreages of willow are compared, the connection between the established area of willow plantations and production costs is clearly seen. The cost for plantation decreases both through new technology and through the increasing numbers of hectares planted with willows.

The possibility of reducing the costs for conventional N and P treatment, £ 5 – £ 14/kg N (Rosenqvist. et al., 1997), is by far the most important economic factor when considering wastewater irrigation of willow coppice as an alternative treatment technique. The increased biomass production and the reduced costs for the farmer (corresponding to £ 0.60/kg N), have a limited impact on the total economic result. Increased biomass production by growing even more vigorous plants would allow an increased N application without increased risks of N leaching. The increased rate of wastewater application that these enhanced yield potentials allows would reduce the cost for each kg N treated.

If there are no existing willow plantations or no immediately available areas for new plantations in the vicinity of treatment plants, it may be appropriate to invest in pipelines to reach suitable areas. An alternative is to offer farmers with suitable land in the vicinity of the treatment works the opportunity to handle the wastewater by giving them appropriate support. If a farmer accepted wastewater irrigation corresponding to 150 kg N/ha/y, he could theoretically be paid up to the alternative cost for conventional treatment, i.e. £ 5 – £ 14/kg N (amounting to about £ 700 – £ 1800/ha/y for the wastewater production during the irrigation season). In practice, however, society is likely to try to profit from a new treatment system by demanding a lower price for wastewater treatment. This, together with the value of the increased biomass production, would give the farmer maximally £ 800 – £ 1900/ha/y. This implies that the farmer has to cover all the costs for pumping and distribution.

Some of the project participants in the middle of the willow forest.
(Photo: Stig Larsson)

Different treatment works have different costs for using vegetation filters depending on the planning situation and the strategy. When costs are low in the vegetation filter system, it is easier for the treatment works to accept higher costs, for pumping the wastewater longer distances. It can be of interest for large treatment works to take only the "excess water" and pump it a longer distance.

Normally when using willow plantations for treating wastewater, the two parties involved are a municipality (or an industry) and the owner or farmer of the plantation. The basis for wanting to enter into a contractual relationship of this kind is primarily mutual economical gain. The municipality is responsible for the handling of the wastewater from the connected citizens. From the municipality’s point of view, the use of vegetation filters will allow decreased investments and operational costs of the required wastewater pre-treatment facility. Less use of chemicals and electric energy, a reduced sludge production and a decreased need of working staff primarily sustain reduction of operational costs. The owner or farmer of the willow plantation will profit from the increase in growth that may lead to greater and more secure harvests.

A contract has to be set up to define the rights and duties of the parties. These rights and duties need to take into account the financial positions of the parties as well as their respective ability to take part in, oversee and verify the object of the contractual relationship. This can be seen as the splitting of risk-taking appropriate for each party. The amount of risk a party is willing to accept depends on the gain he is likely to make.

Today it is usually felt that there is a greater gain for the municipality to have access to a vegetation filter than for the willow farmer to acquire extra water and nutrients. It is also the municipality that can influence the quality of the wastewater and can better handle unpredicted extra costs. Therefore the farmer should be able to demand that the municipality take the major economic responsibility. It is also fair that the municipality should have the responsibility for the risks with the wastewater, even after it is delivered to the willow farmer. The municipality should be liable to pay compensation to the farmer for costs incurred by variation in the amount and quality of the wastewater.

The municipality should demand from the farmer that application of wastewater would be made in accordance with recommendations from authorities. The farmer should have the responsibility to take care of the plantation so it can be used for the whole contract period. A contract about buying of wastewater would last over a long period of time and the different parties would probably adjust their operations with the assumption that the contract will last the predetermined time. Therefore it would be necessary to have a mutual period of notice.

Usually in this kind of contract the deliverers of the product pay the receiver. This can lead to problems if bills are not paid. The farmer should have the right to cut off the supply if payment is absent. The municipality, in turn, should have the right to have access to the plantation even if the plantation area change owners.

If there are many willow farmers receiving wastewater they can create a union or co-operative. An association of farmers or landowners can then carry out the negotiations or even be a contract party with the municipality. In the latter case the association could have the form of a trading company.

3.3 Social aspects

Projects involving the use of reclaimed water for irrigation usually face problems with public acceptance. Public perceptions are constantly changing because they are influenced by many different factors (age, gender, economic status, level of education and political persuasions) and current events. It is important to treat the public acceptance with the same consideration as anything else in the realisation phase of project.

Reuse of water and nutrients replaces natural water supplies and manufactured fertilisers. The willow biomass system itself could very well be characterised as an ecologically and socio-economically sustainable and alternative farm crop, by providing rural development and reducing dependence on imported energy. Therefore, it is an integrated part of society that concerns everyone in the local community. The system has more societal impact than many other wastewater systems due to the fact that it requires large land areas.

It is important that the citizens feel that they are part of the system, since it depends on their co-operation. The citizens can "destroy" the system performance by "polluting" the resource on purpose or by carelessness. If the system is working properly it serves the citizens and one must not forget that the citizens pay for it (as for any wastewater treatment).

"Dubletten", a commercial Swedish toilet for diverting urine and faeces.
(Photo: Arne Backlund)

To implement an initial acceptance from the public the following strategy (or parts of it) is suggested:

1. Allow a budget for information/communication/awareness-raising/education/training. This should be done at the same time as the rest of the project is budgeted.
2. Choose one message-bearer and educate and train him/her. This person can be a management staff member, a professional or an ordinary citizen in favour of the idea.
3. Identify the target audience. This can be citizens, farming communities, decision-makers (political/environmental authorities), environmental groups etc.
4. Begin informing with, for example, meetings, media communication, information brochures and questionnaires.
5. Reach consensus.

The citizens should be aware of potential problems with the systems before the project starts. If something goes wrong with the system, the citizens have to be informed so that they understand the magnitude of the problem and how they should act upon it. They should also be informed about how the problem will be solved.

A strategy, such as that described above, could possibly be useful in case a full-scale application of the system is undertaken at Larissa, as has been discussed there.

The aspects of reducing the pressure on energy and water resources were analyzed for the region of Larissa, an area with rapid economic growth. The possibility of using an integrated solution for municipal wastewater management and agricultural land use around big cities like Larissa, in such a way as to preserve natural beauty and enhance animal and plant life, was also investigated.

Larissa is located in central Greece within an agricultural area. One of the most important problems of this area is the demand on water resources which has become even more severe in the last couple of years. The main income of the town is based on agricultural production, and, therefore, the lack of water recently has created serious problems. It is obvious that in the wider area of Larissa there is need for efficient use of every possible water resource. Thus reuse of properly pre-treated municipal wastewater is foreseen as an important complementary water resource for crop production.

Also, the need for replacement of fossil fuels with renewable and environmentally friendly biofuels has become increasingly pronounced. Further, alternative agricultural crop production, to balance the general over-production of cereals and cotton on the market, is generally promoted. The municipality of the town has already expressed interest in the extension of the activities on willow growing for energy production on a larger scale. Thus, the use of municipal wastewater for irrigation of willow coppice, as a crop system for producing bioenergy in the area of Larissa, is a possible solution to the existing economical and environmental problems, possibly also improving the social life of the people.