Overview of the current limits of renewable energy

The surface density of the solar energy at ground level is low. Its average annual value in the temperate can go roughly from 1200 to 1900 kWh/m2/yr (kilowatt hours per square meter / year) which correspond respectively to 3.3 and 5.2 kWh per day on average. This will generally involve the exploitation of renewable energy sources requires large areas for water collection entail considerable territory thus causing a high unit cost of secondary energy (thermal, electrical, etc.). Produced and making it difficult to achieve competitiveness economic.

• Another major flaw is that its renewable energy production in general is intermittent in time because of daily variability, seasonal, climatic conditions of the solar primary. Precisely because of the intermittence of the generation of energy, as will be seen later, the economic value of the kWh of renewable sources is considerably lower than that of the traditional and the addition of the environmental value fails to compensate for the deficit due to intermittency.

• A third aspect to consider is the fact that the most promising renewable energy, such as wind and photovoltaics, directly produce electricity, this feature, which is considered positive in terms of the electrical energy is considered as a form of fine energy, does not allow to expand into other slices of the energy market, such as transport, rapidly expanding industry that produces high CO2 emissions and will continue to increase its concentration in the atmosphere.

Together with these technical limitations outlined above, the new renewable sources also show some negative elements of a social nature that hinder their spread:

• Occupation of the territory: the density of surface energy involves the need to occupy with the installations of the various renewable sources territorial areas very large in comparison to those occupied by the conventional installations.

• Changing the landscape: the vast expanses of facilities required for the production of renewable energy presentanoun decidedly impactful, both visually and to the shape of the components.

• Changes in Earth's albedo: in relation to the large-scale deployment of solar photovoltaic and thermodynamic immediately arises a concern that large mirrored surfaces can cause an alteration in terrestrial albedo, thus causing a change in the energy balance of natural the planet.

• Noise of wind turbines: wind turbines during operation generate

noise. This disorder can achieve noise intensity which exceed those permitted by law.

 

Assessments of economic efficiency

The current incentives are not commensurate neither economically efficient nor to the costs avoided by the use of renewable sources. The energy issue is usually dealt from a logic-supply of energy, in particular electricity, based on the predicted consumption and with a decidedly partial approach, not able to recognize the interdependencies and feedbacks between the energy industry and other economic sectors, and within the energy system itself. It 'obvious inadequacy of energy planning inattentive to the actual dynamics of energy demand by end-use from the quality of energy demand. The latter is in fact characterized by a strong qualitative differentiation that we can schematize in:

-Electric

-High temperature thermal

-Low temperature thermal

-Mechanical (such as fuels for vehicles etc.)

To a strong differentiation of real demand has so far responded with an offer substantially undifferentiated energy based almost exclusively on electricity and natural gas, both forms of energy of high value and high-calorie.

Estimate of the cost of investments in various renewable Italian in the current situation:

- 40 billion euros to reach 17% of the renewable heat

- 88 billion euros to reach 6-7% of the renewable electricity.

Photovoltaics and wind power are subject to incentives that fall on the community by paying the electric bill. Within a dossier prepared by ENEA (source: ENEA - National Agency for New Technologies, Energy and Sustainable Economic Development) emphasizes, inter alia, the opportunity to review overall, also in view of the definition of National Action Plan for renewable energy, an incentive system that dramatically resize the incentives to RES (renewable energy sources) in favor of electric and thermal.

Focusing on renewable thermal energy has several repercussions of economic, environmental and social issues, such as:

• optimization of synergies with energy efficiency policies, such as interventions in buildings in the areas of residential and tertiary

• maximizing the benefits for end users (households and enterprises)

• greater ability to solicit investments spread with limited incentives

• integrated solutions at the local level (simultaneous use of organic waste, agricultural waste and forestry, livestock manure and sewage sludge)

• involvement of the agricultural world for the supply of plants with a short chain

• organization of Italian industrial clusters powered by renewable energy, from the mechanical engineering, which already offers technological energy efficient and that in the ongoing conversions can find new outlets applications in renewable energy sources

• strengthening the network of ESCOs and distribution of energy services

• training and employment for qualified personnel

Currently the heat sector contributes only 2.2 Mtoe national energy mix, ie 29% of the total renewable, compared with a total potential of renewable energy in 2020 by 60% to 16 Mtoe in absolute terms (ie more than seven times the current value.) This potential is little known by the general public, it is not considered from the political world, is overlooked by the debate on energy strategies, and access to incentives so incongruous and messy. "The potential affordable to 2020 renewable energy in the heating sector is at least 16 Mtoe - of which at least 9 Mtoe obtained by intensive use of domestic bioenergy (biofuels, solid, liquid and gaseous fuels derived primarily from waste and residues), at least 6 Mtoe from heat pumps that use the energy from a low temperature in the air, water and soils, and at least 1 Mtoe by solar thermal plants. " All this would greatly exceed the level of 21 Mtoe from renewable sources, corresponding to the objective of 17% required to Italy in the scenario of rationalization of energy consumption of the energy and climate package, without having to resort to imports of biofuels from crops Dedicated dubious environmental and social compatibility.

 

Cost on the balance of payments (import-export)

Who produces the photovoltaic and wind power that we install in Italy?

Wind Power

Costs: approximately EUR 1.1 million per MW

Photovoltaics:

Sharp is the undisputed leader of the global PV market. To do the lion's share in the top 10 Germans and Japanese, but the Chinese advance ... Here is the list of the PV cell manufacturers:

Analysis of the ranking are noticed 4 Japanese companies, including two in the first three positions, and 3 German companies. No coincidence that Japan and Germany are respectively first and second for photovoltaic power installed. In the ranking for the first nations are the Japanese and the Germans seconds. In third place strong rise in the Chinese, who have overtaken the United States (which they had invented the photovoltaic panels). No trace of the few Italian companies.

Costs Photovoltaic: about 3.3 million per MW peak. Are calculated for ground systems, extrapolating those of the larger exchanges polycrystalline silicon recently made in Italy. It is perhaps worth noting that, without incentives, the cost of photovoltaics are significantly higher, as a cost of 3.3 million / MW in a market no one would invest in PV. Efficiency values ​​typical for amorphous silicon solar cells, polycrystalline, monocrystalline, vary between 6% and 18%, for which we can affirm that in terms of space for a kilowatt of power monocrystalline silicon serves an area of ​​about 6-9 m2, for the polycrystalline serves an area of ​​about 8-10 m2, whereas for the amorphous of about 12-16 m2.

The albedo of the Earth plays a very important role in the warming of the global climate. The albedo tells us what percentage of solar radiation is reflected directly back into space, preventing the Earth to absorb the energy. This fraction is usually around 30%. Changes in land use and the Earth's climate can lead to changes in albedo, which in turn have an impact on the Earth's radiation budget and therefore lead to a warming or cooling of the Earth's surface. The loss of sea ice in the Arctic Ocean due to a significant change in albedo on a regional scale. Here, a highly reflective surface (ice) is replaced by a surface with low albedo (the ocean water). The result is a clear increase in the absorption of the energy that, at the regional level, leads to greater warming than expected globally. Finally, the loss of forests and the parallel increase of land used for agriculture and grazing cause an increase in albedo, as the agricultural land is clear of forests. This contribution to the cooling of the Earth can not compensate for disadvantageous, however, other aspects related to the loss of the rainforest: the rise of CO2 in the atmosphere and the loss of biodiversity.

Mtoe = million TOE. TOE = Tons of oil equivalent. 1 MWh = 0.086 toe.

Were calculated by extrapolating the current ones of a plant of 30 MW turbines with unit capacity of between 2 and 3 MW. For the occupation of territory took the conventional reference value for wind power of 10 watts / sq. The 84,000 acres that are derived from the total area around the wind turbines, which of course can be used for agricultural, farming or similar. But certainly not for all purposes. 4,200 acres area is the area actually occupied by the 3000-4000 turbines needed to install the 8,400 MW and that is not usable, in safety, for any other use.

 

07/01/2011

 

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Translated via software

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Source:

Italian version of CercaGeometra.it