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Cons:

The purchase and set-up of wind turbines can be expensive

Wind turbines require certain constant speeds to be productive (13 mph for large turbines, 9 mph for small turbines)

most all biofuels used today cause more greenhouse gas emissions than conventional fuels if the pollution caused by producing these "green" fuels is taken into account, two studies published Thursday have concluded.

The benefits of biofuels have come under increasing attack in recent months as scientists have evaluated the global environmental cost of their production. The new studies, published by the journal Science, are likely to add to the controversy.

When you take this into account, most of the biofuel that people are using or planning to use would probably increase greenhouse gasses substantially," sai

We are working to produce biofuels that are low cost, low carbon, sustainable and able to fulfil the world’s transportation fuel needs on a large scale without compromising food production

Because pure hydrogen does not occur naturally, it takes energy to manufacture it. There are different ways to manufacture it, such as, electrolysis and steam-methane reforming process.

In electrolysis, electricity is run through water to separate the hydrogen and oxygen atoms. This method can be used by using wind, solar, geothermal, hydro, fossil fuels, biomass, and many other resources.

The more natural methods of making electricity (wind, solar, hydro, geothermal, biomass), rather than fossil fuels, would be better used as to continue the environment-friendly process of the fuel. Obtaining hydrogen from this process is being studied as a viable way to produce it domestically at a low cost. Steam-methane reforming process extracts the hydrogen from methane. However, this reaction causes a side production of carbon dioxide and carbon monoxide which are greenhouse gases and contribute to global warming.

Current estimates for an entire system, including fuel and air supply, insulation, fuel cells stack, reformer and desulfurizer, piping, labor, depreciation, system control and power electronics is as high as $4000 per kW [20].

This initiative, supported by legislation in the Energy Policy Act of 2005 (EPACT 2005) and the Advanced Energy Initiative of 2006, aims to develop hydrogen, fuel cell and infrastructure technologies to make fuel-cell vehicles practical and cost-effective by 2020

Why are governments, private businesses and academic institutions collaborating to develop and produce them? Fuel cells generate electrical power quietly and efficiently, without pollution. Unlike power

that use fossil fuels, the by-products from an operating fuel cell are heat and water

Power density: Power from a solar array is limited by the size of the vehicle and area that can be exposed to sunlight. While energy can be accumulated in batteries to lower peak demand on the array and provide operation in sunless conditions, the battery adds weight and cost to the vehicle. The power limit can be mitigated by use of conventional electric cars supplied by solar (or other) power, recharging from the electrical grid.

the world’s fastest growing renewable energy source for more than a decade with an average annual growth rate of over 20%.

increasing generating capacity by 50%. With more than 25,170 MW of wind energy

ind energy in the United States could provide as much as 10,777 billion kWh annually

3.Wind Turbines Interfere with Television Reception.

Some of these blades can have a span of 100 or more feet.

birds easily fly into the blade path and get killed.

One of the main disadvantages is the initial cost of the equipment used to harness the suns energy

A solar energy installation requires a large area for the system to be efficient in providing a source of electricity

pollution can degrade the efficiency of photovoltaic cells. Clouds also provide the same effect, as they can reduce the energy of the suns rays

Mutant cellulose yields biofuel more easily

Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetative cover. This wind flow, or motion energy, when "harvested" by modern wind turbines, can be used to generate electricity.

The terms "wind energy" or "wind power" describe the process by which the wind is used to generate mechanical power or electricity

The terms "wind energy" or "wind power" describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power

Major changes will be needed to grow, handle, transport and store the immense quantities of biomass -- mostly lignocellulosic feedstocks such as switchgrass, crop residues and forest wastes -- necessary to continually feed electric power generation stations and produce biofuels for transportation,

converting to a system in which biomass provides much of the country's energy will require new ways of thinking about agriculture, energy infrastructure and rural economic development.

With low emissions of pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter as well as dramatically lower emissions of carbon dioxide (CO2),

Geothermal energy has been used for thousands of years in some countries for cooking and heating.

How it works

Hot rocks underground heat water to produce steam. We drill holes down to the hot region, steam comes up, is purified and used to drive turbines, which drive electric generators.

By "biofuels" on this page, I mean fuels for vehicles, such as "biodiesel" and "bioethanol" - although you can also use the term "biofuel" to cover any kind of fuel made from living materials or their waste.

How it works Biofuels are made from two main sources: Growing crops such as corn, sugar cane, soya or rapeseed; or from palm oil Growing algae

Biofuels are made from two main sources: Growing crops such as corn, sugar cane, soya or rapeseed; or from palm oil Growing algae

Biomass is organic material made from plants and animals (microorganisms). Biomass contains stored energy from the sun. Plants absorb the sun's energy in a process called photosynthesis. The chemical energy in plants gets passed on to animals and people that eat them. Biomass is a renewable energy source because we can always grow more trees and crops, and waste will always exist. Some examples of biomass fuels are wood, crops, manure, and some garbage. When burned, the chemical energy in biomass is released as heat. If you have a fireplace, the wood you burn in it is a biomass fuel. Wood waste or garbage can be burned to produce steam for making electricity, or to provide heat to industries and homes.

Crops like corn and sugar cane can be fermented to produce ethanol. Biodiesel, another transportation fuel, can be produced from left-over food products like vegetable oils and animal fats.

Ethanol and biodiesel were the fuels used in the first automobile and diesel engines, but lower cost gasoline and diesel fuel made from crude oil became the dominant vehicle fuels. The Federal government has promoted ethanol use in vehicles to help reduce oil imports since the mid-1970s.