Renewable Energy

Renewable energy resource

Renewable energy resource .............................................................................................. 1

• Part 1 - Classification of energy resources ............................................................. 2
• Energy ≠ power ........................................................................................................................ 4
• Part 2 - Total primary energy supply (TPES) ................................................................ 4
• Energy density and population density ............................................................................................ 5
• Energy intensity .................................................................................................................... 5
• Grid party .................................................................................................................................. 6
• Environmental impact ................................................................................................................... 6
• Part 3 - The international energy framework electricity ............................. 7
• The international energy framework hydropower ........................................................................ 7
• The international energy framework solar pv ............................................................................... 7
• The international energy framework wind power ....................................................................... 7
• Part 4 - The electrical network ....................................................................................... 7
• Transmission in Italy .................................................................................................................... 8
• Load diagrams ......................................................................................................................... 8
• Smart grid ............................................................................................................................... 10
• Energy storage system (ESS) ......................................................................................... 11
• Parte 5 hydroelectric energy ..................................................................................... 12
• Part 6 run of river hydroelectric ............................................................................. 15
• Medium head .................................................................................................................................. 16
• Low head ........................................................................................................................................ 17
• Part 7 hydroelectric turbines ..................................................................................... 17
• Pelton .............................................................................................................................................. 18
• Francis ............................................................................................................................................ 18
• Kaplan ............................................................................................................................................ 18
• Impulse ≠ reaction turbine .......................................................................................................... 19
• Main components ........................................................................................................................... 19
• Specific speed ............................................................................................................................. 19
• Part 7 wind resources ....................................................................................................... 19
• Global potential scale ..................................................................................................................... 20
• Genesis of atmospheric circulations ........................................................................................... 20
• Regional features ........................................................................................................................ 20
• Atlases of wind ........................................................................................................................... 21
• Local analysis for design purposes ................................................................................................. 21
• Wind profile ................................................................................................................................ 21
• Measurements ............................................................................................................................. 23
• Data ............................................................................................................................................. 23
• Complexity ..................................................................................................................................... 23
• Part 8 wind energy, wind turbines .............................................................................. 24
• Type of aerodynamic force ............................................................................................................. 24
• Drag ............................................................................................................................................ 24
• Lift .............................................................................................................................................. 25
• Types of wind turbine ..................................................................................................................... 26
• Vertical axis generators .............................................................................................................. 26
• Horizontal axis generators .......................................................................................................... 26

Part 1 - Classification of energy resources

Definition of energy is based on:

Origin

• Primary energy (PE): is an energy from found directly in nature (oil,natural gas,coal,sunlight,biomass,wind,flowing water)
• Secondary energy (SE): is a carrier of energy produced by conversation from a primary source (electricity, hydrogen)

Availability → energy

• Non renewable: are available in limited supplies, usually because they take a long time to replenish (ex: nuclear, oil, natural gas), oil and gas take many millions of years to form
• It comes from sources that will run out or will not be replenished in our lifetimes, or even in many, many lifetimes
• Renewable resources: → on the other hand, replenish themselves (solar,wind,biomass,hydro,geothermal), the most of them come from sun
• It is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat

Dispatchability

Dispatchability is imposed by the consumer and it is connected to PROGRAMMABILITY (depends on the source) and INTERMITTENCY (due to the distributions, time scale seconds and minutes).

It is distinguished in:

• Dispatchable sources → can be used at the request of power grid operators (the end users need the energy)
• Dispatchable generation: refers to sources of energy that can be used on demand and dispatched at the request of operators, according to market needs, the generators can be turned on or off their power output according to an order
• Dispatchable plants: have different speed at which they can be dispatched. The fastest plants to dispatch are hydroelectric power plants and natural gas power plants.
• Non-dispatchable sources: wind power and solar power which cannot be controlled by operators

NB: The only types of renewable energy that are dispatchable without separate energy storage are hydroelectric, biomass, geothermal and ocean thermal energy conversion.

NB: For instance, the heat from a geothermal vent could be considered a primary resource, but the heat made from burning fossil fuels is secondary energy.

The increase in production of energy from intermittent and not programmable renewable sources poses two problems for programmable energy plants:

• Volume, because a reliable production capacity is needed to meet demands not covered by wind turbines and solar panels; Any time scale (from years to minutes). It’s hard to plan Hydro resources at the scale larger than the season. Wind and solar, at this time scale, are easier to plan.
• Flexibility, because the need for additional energy can vary greatly over very short periods of time (seconds). Hydro does not vary at short scale (the Hydrology has a response time scale ranging from hours to many days). Solar and wind are very variable at this time scale.

Some forms are stored solar energy such as rainfall and wind power which are considered short-term solar-energy storage, whereas the energy in biomass is accumulated over a period of months, as in straw, or through many years as in wood.

Sun is the main source of energy for carbon cycle, the energy of sun is able to store in soil carbon.

Carbon flows between each reservoir in an exchange called the carbon cycle, which has slow and fast components. Any change in the cycle that shifts carbon out of one reservoir puts more carbon in the other reservoirs. Changes that put carbon gases into the atmosphere result in warmer temperatures on Earth.

Primary energy (traditional or green energy) → transformation → secondary energy (gasoline/gas and electricity/heat) → consumption.

51% heating and cooling: 10 renewable energy, 5 non-renewable.

32% transport: 3.3 renewable, 0.8 n-r.

17% power: 26 renewable.

➔ the future will be that the oil production will be less than 20%, the other from hydro, electricity in order to reduce the amount from oil and improving the energy from renewable energy.

Energy ≠ power

E(GWh): how much work has been done by the device, related to the revenue of the device.

P(MW): is a device concept, related to the cost of the device, store capacity.

CAPACITY FACTOR link between E and P, ratio between how much energy you are producing (under the curve) and how much energy you can potentially produce (outer the curve x the hour of production).

CF for wind 0.3/0.35, CF for hydro 0.7.

Hydro power is useful for fill the gap due to the intermittency of wind or solar but if you look at the time scale (1 year) is not that good, because of the variability and you can not predict → programmability is easier with solar energy.

Hydro is crucial to help whit the intermittency of the sun → from hydro we can get more stability in the electrical grid.

Part 2 - Total primary energy supply (TPES)

Divided in coal, oil, gas, nuclear, biofuel (mostly in Africa).

Nowadays we are less dependent on oil but coal is the same, because is cheaper and easier, renewable are growing even if very slowly.

We need nowadays 15 MTOE (million tons oil energy) → switch to energy/year we need 3130*10 Twh → switch to power E/8760 h=20 Tw.

920 ∗ 10 = = 2.5 ℎ 97.5 ∗ 10 2.

We get from the sun 0.15 kw/m (total energy from the sun), the efficiency of a solar panel 1x12 m is 0.2. The net power from the sun we can get is 0.03 kw/m 2.5 2 = = = 100 ℎ 0.03 2 2 2.

Power from the sun real (the effective one) is 7/10 W/m, we need in real life 400 m but how → → 2 much area is available in Italy for a person to produce solar energy? 2000 m we need to → sacrifice 20% of land in Italy the renewable energy have a very low energy density.

Energy density and population density

Until now we made the hypothesis of homogeneity but the population and irradiation distribution are spatially out of phase, where there is energy are no people.

→ Why is it useful to know how much power is consumed by land-area? almost all renewables are harvested on land, and it is possible to quantify the potential power production from renewables in exactly the same units as consumption: watts per square meter. Concentrating solar power stations in deserts, for example, can produce 15 or 20 watts per square meter, on average, year-round, day and night.

Countries could match today's power consumption if they covered, for example, 20 percent of their land with energy crops. For average countries, therefore, it is technically possible to live on renewables, and solar power in deserts, solar parks and wind farms are all feasible solutions.

Countries with power consumption per unit area of more than 1 watt per square meter, like Britain, Germany, would have to industrialize much of their countryside to live on their own renewables. Alternatively, their options are to radically reduce consumption, use nuclear power and buy additional renewable power from other, less densely populated, countries.

Solution: super grids, the idea is to transfer energy where is very requested, move electricity → along many kilometres but most of it dissipates the technology to produce superconductor.

What is the growth in energy consumption related to? There is a close correlation between wealth/individuals and consumption. Growing populations consume more energy. Availability of energy allows populations to grow.

Energy intensity

Energy intensity = ∗ E = energy in related to N (number of inhabitants), PIL pro capite, main e.