Saturday, October 1, 2016

Global Potential of Energy from Biomass and its formulation

World largest power plant employing Biomass is Drax, UK, which has installed capacity of 3960 MW with 1320 MW from Biomass.
Drax generates 8 TWh energy from Biomass Per year.
which is tantamount to 22 GWh/day.

The potential calculation for Biomass:
Average irradiation on earth= 1500 kWh/m^2/year
=171 W/m^2
Photosynthetic efficiency is quite low= 0.4% only
So, Power density of tree= 171*0.4%= 0.68 W/m^2
Thermal conversion efficiency= 25%= 0.68*25%= 0.171 W/m^2
Energy density= 0.171*24*365/1000= 1.5 kWh/ year/m^2

The overall efficiency comes out to be only 0.1%.

Products:
Biofuels= Ethanol, extensively used in brazil
Biogas= Methane, Methane is a green-house gas (GHG). The global warming potential of methane is 72 times higher than global warming potential of CO2 for the period of 20 years. Methane contributes 7-9% to global warming.

Note: Algae has higher photosynthetic efficiency than crops so better for biomass energy conversion.
The average carbon footprint of Biomass plant is 230 gCO2/ kWh, much higher than other renewables but much lower than the coal-fired power plant.

Global capacity= 93 GW
                          = 433 TWh/ year
                          =1.9% of global energy demand
                          = 7.6% of all renewables
Besides electricity, more energy is in the form of thermal energy,
Global thermal capacity= 305 GW
                                       = 2300 TWh/ year
                                      = 12500 TWh/ year including cooking, heating, transportation
All Biomass in combine accounts for 12 % of the global energy use and 63% of the renewable energy shares.
= 1.69 kWh/person/day
= 0.58 Human Unit
                                      

Saturday, September 24, 2016

Some facts about Solar Energy

Solar Energy is:

  • Scalable
  • Cheap and Predictable
  • Low Capacity factor= 10-20% only
  • Lifetime is quite good- 20-30 years.
  • Carbon footprint is more than Wind energy- 48 gCo2/kWh
  • Global installed capacity is 227 GW
  • Global Energy Production is 235 TWh, i.e 0.08 kWh/Person/day
  • Solar energy serves about 1.2% of the global energy demand
  • Solar energy accounts for 4% of the renewable energy produced throughout the world.

Friday, September 23, 2016

Something to know about Wind Energy

Only 59.3% of the energy of the wind can be converted into mechanical energy. The Commercially available wind turbine has about 40-50% of the wind energy into mechanical energy. Average Co2 footprint for Wind energy is 11 gCO2/kWh for onshore farm and 12 gCo2/kWh for the offshore farm.

Today the wind energy share 2.3% of the global energy demand and this is about 10% of the all renewable energy produced in this world. This data is tantamount to 0.19 kWh/person/day= 0.07 Human unit/person/day

Denmark has developed good amount of wind energy. The wind installed capacity in denmark is about 5 GW and the annual energy production is 14.13 TWh.  Looking at the kWh/W, its only 2.8 kWh/W. The capacity factor comes out to (2.8/(365*24/1000) 0.32 only. In comparison with the capacity factor of hydro electricity 0.7, it can be concluded that the wind energy produces less electricity per installed capacity than hydro electricity. The amount of energy produced from wind turbine depends on the wind speed. The wind speed is dependent on daily and seasonal wind profile, terrain, and the height at which we extract energy from wind.

Power from wind turbine
E= 1/2 mv^2
m=density* volume
*A*v*t
E/t= 1/2*ρ*A*v*v^2
P=(1/2) ρ*A*v^3

The power produced from wind turbine is proportionla to cube of wind velocity. 

A turbine with rated power 1.5 MW is the power that can be produced by wind turbine at rated speed. The efficiency of turbine drastically reduces at low speed as well as high speed apart from the rated speed.

Wednesday, September 21, 2016

Key Points to be remembered about Hydro Electricity

Typically, the carbon footprint of hydroelectricity is only 24 gCo2/KWh whereas the carbon footprint of Coal fired power plant is much larger, 820 gCO2/KWh.

In 2015, hydroelectricity was only 16.6 % of the global energy demands. for 7.4 billion people living in this world, this energy is equivalent to 1.47 KWh/person/day which is tantamount to 0.5 human unit only. The share of hydroelectricity is considered to rise up to 25% of the global energy share.

Energy density calculation in hydropower design
Suppose, in a suitable land for hydropower development has the rain gauge reading of 500 mm/ year.
Rain= 500 mm/year
Rain= 0.5m^3/m^2/ year= 0.5*1000*10
= 500 kg/m^2/year

Potential energy of water Epot= mgh
=500*9.8*100 (h=100)
=490n Kj
Epot= 490*9.8*100
=0.14 KWh/m^2

Including losses, evaporation, and leakage, only 20% energy from hydropower dam is used for voting.

Use of Energy by sector

Transportation= 25% of the global energy use.

Residence and Buildings= 20% of global energy use

Industrial Sector= 54% of the total energy used.

Rest of the sector share only 1% energy.

Transportation= fuel or battery or direct supply for Car, Bus, Train, aeroplane sector
Residential= Heating, Cooling, Refrigeration, Air conditioning, Cooking, lighting etc.
Industrial= Iron and steel industry, Aluminium industry, wood industry, food industry, chemical industry, irrigation projects, drinking water projects, fine products etc.