About urbane wind turbine investment

These costs consist of: complete UWT installation including the engineering, safety measures, monitoring, supporting construction, transport and mounting, proof of operation (commissioning) and the acceptance. Likely additional costs will arise from:

feasibility studies, location selection, structural assessments (if mounting the turbine on a building), obtaining permits and project management. In order to at least partially compare the investment costs of the different turbines, the cost per kW installed has been calculated. The figure provided is the result of: (total investment - remaining value after 10 years) / nominal capacity.

The remaining value has been estimated as 20% of the investment for all turbines except for Ropatec. This is because the manufacturer of Ropatec guarantees to buy back his turbine after ten years for a fixed price. However, it should be noted that all costs are estimates at the time of publication and could change.

Also, all calculations are only indicative, as the separately charged costs cannot be estimated and the performance figures provided by the suppliers and manufacturers have not been verified in practice. Therefore, although these figures provide a rough guide to costs, further investigation on an individual project basis is necessary.

4.1.2 Periodic costs

The periodic costs include maintenance, part replacements, transport costs related to the on-site work, the possible insurance costs (including the third party damage liability), the costs of any equipment replacements and the cost of a complete check of the system after 10 years of operation. Again, these costs have been estimated on the basis of information from suppliers and manufacturers and should be treated as indicative costs only.

4.2 Benefits

4.2.1 Financial incentives

The financial incentives available differ between the Netherlands and the UK.

The Netherlands: E.I.A. – Energy Investment Deduction for profit-making organisations: it is possible to obtain the E.I.A. with a maximum of € 5000 per turbine for turbines with a nominal power < 25 kW.

M.E.P. – Electricity Generation Environmental Quality: applies to the total energy generated by a renewable energy installation. The level of the M.E.P. subsidy per kWh is set by the government and laid out in the Ministerial grant scheme regulation.

UK: A grant can be obtained from the Low Carbon Building Programme (LCBP) in the UK, to cover up to 50% of the installation cost.

Some provinces and municipalities provide additional subsidies as a part of their own renewable energy development programmes. Most commonly these

subsidies are a part of local measures against climate change and are usually reconsidered yearly.

4.2.2 Savings through using of the generated electricity

Using the electricity generated at the location means direct savings for the owner through a lower electricity consumption bill. The savings depend on the price

paid to the electricity supplier by the consumer for electricity supplied from the grid. For example, the customers of the supplier ENECO in The Netherlands pay approximately 21 €cents/kWh. In the UK, typical cost of electricity for flats and households can range from 11p to 16p/kWh. These prices depend very much on the time during the day (or night) when the electricity is used.

Selling to the grid

If there is a surplus of electricity generated from a small wind turbine, in theory it can be sold and the owner decides to whom. Most commonly it would be sold to

an electricity supply company. The price can differ considerably from one electricity company to another, so it is worth investigating several options. For example, in the Netherlands, ENECO pays 4.088 €cents/kWh excluding VAT (2007).

The electricity supplier Green Choice gives discount on the supplied electricity to his customers who feed their energy surplus into the grid. Selling electricity to the grid is regulated differently in each country. If the owner of a UWT wants to sell his electricity to the grid, (s)he may need to have a specific type of meter that measures both ways: the electricity sold to the grid and the electricity consumed from the grid. This type of meter is readily available but is not installed as standard and so may need to be installed as part of the wind turbine installation.

4.3 Efficiency of UWTs

The efficiency of wind turbines is most commonly measured in terms of cost-effectiveness, i.e. in cost per kWh of the produced electricity. In a technical context in order to determine the revenue generating potential, the efficiency would be measured as a yield, measured as the number of kilowatt-hours produced per square meter of rotor area per year (kWh/m2/yr).

At this moment there are insufficient yield figures for UWTs from real projects to draw definitive conclusions on efficiency. This means that the efficiency can only

be estimated and that the comparisons between various types of UWTs cannot be done reliably.

Nevertheless, an indicative comparison is provided in Tables 4

and 5 by using the "reference yield" from the manufacturer calculated at two specific wind speeds namely:

o 12 m/s: a figure close to the nominal wind speeds of most UWTs

o 5.5 m/s: a good average wind speed for operation of the investigated UWTs.

Explanation:

A = rotor area

Vnom, Pnom en A have been provided by the vendors (see table 2). Pref is the result of the formula: Pref=(vref/vnom)3 x Pnom

Comparison with large turbines

The initial (capital) investment per kW can vary greatly between different UWTs: according to the information provided by suppliers and manufacturers it can be between 2,400 and 9,100 €/kW. In comparison, the initial investments for large turbines are about 1000 €/kW for land installations and about 2000 €/kW for offshore (investments in solar photovoltaic (PV) systems are approximately 6,200 €/kWp installed).

The expected yield, assuming there is an average wind speed of 5.5 m/s, would very approximately amount to 150 - 400 kWh/m2/year. The yield of large turbines

varies between 800 and 1200 kWh/m2/year.

The figures indicate that large turbines clearly outperform UWTs and this is not surprising, as the conditions under which they are implemented are very different.

However, UWTs are still in a development phase and although it is unlikely that they will ever reach the yields of large wind turbines (since wind resources are not the same in urban environments) it can be expected that costs will fall and the efficiency of UWTs will be significantly improved. Manufacturers of UWTs in the

Netherlands and the UK expect a price reduction of about 40% by a ramped-up production of at least 500 turbines per year.

Finally, UWTs generate electricity that can be directly consumed at the site of generation. This means that the produced electricity is effectively being used

against the consumer price which is approximately 5 times higher than the price paid for the electricity produced by large turbines.

Considering the installation capacity, costs and the expected yield, it is better to compare the UWTs with solar PV production of electricity.