Renewable Energy I Passive solar Active solar Large-scale solar thermal Solar photovoltaic – residential, commercial Wind power Biomass.

Renewable Energy I

• Passive solar

• Active solar

• Large-scale solar thermal

• Solar photovoltaic – residential, commercial

• Wind power

• Biomass

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Passive solar – design, siting. In spite of 40 years of availability of tried and true designs,less than 10% of new single-family dwellings meet passive solar standards. Cost?Acceptance?

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Active solar collection for residences is cost-effectivein most parts of the US. Tax incentives make the payback period economically advantageous. Howeverthese tax advantages come and go with budgetand political pressure.

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www.powerfromthesun.net/chapter1/Chapter1.htm

Large-scale solar-thermal systems utilizeStiller heat engine or steam-to-turbine systemsto power electrical generators. Solar poweris predictably time-variable, and must be accompanied by storage back-up (pump-storagehydroelectric, for example). Alternativecapacity from fossil or nuclear systems isgenerally assumed to be required for largeutility-supplying systems.

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Large-scale solar collection systems impact land use and ecosystems. Often, these environments are otherwise considered ‘waste’ land.

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The economics of solar photovoltaicpower generation at the medium andsmall scale depend on state-levelregulations that support ‘reverse metering’allowing the owner to be paid forpower entering the utility grid. Withoutthese regulations, investment in solarphotovoltaics may not be economicallyviable.

A key factor in the economics of investment in solar photovoltaic systems is the payback period giventhe initial investment. Payback maynot occur at all if the system requireslarge battery storage, increasing thecost to levels such that the paybackperiod exceeds the replacement timeof solar cell and battery components.

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Solar photovoltaic systems are available at residential and commercial scale. For large-scale systems, land-use impacts are considerable. The environmental impact of solar cell manu-facture has come under scrutiny, although with appropriate safeguards, the impactsare minor.

www.renewableenergyworld.com/rea/news/article...

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Capacity factors are a key measure usedto assess the availability of power to gridsystems. Fossil fuel and nuclear powerplants have capacity factors inthe 90% range

For wind and solar, capacity factorsare in the 15-20% range. This means that wind and solar sourcesmust be systematically overbuiltto assure a robust power supply,or the renewable sources mustbe backed-up by fossil fuel plants.

Natural gas-fired turbine systems areparticularly useful as back-up power sources.

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prairieroots.files.wordpress.com/2007/10/moja..

The ‘beauty’ of wind towers is very much in the eye of the beholder. In most areaswhere surveys are done in advance of wind farm development, about 35% of thepopulation favors wind farms; about 35% are opposed for various reasons, mostlyaesthetic, and the rest, about 30%, have no opinion.

In many areas, local municipalities face difficult political choices as strong pro and conviews emerge among local landowners. In rural areas, leasing of space for wind farmdevelopment is an important source of income.

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The incidence of bird (raptor) and batdeaths related to wind towersis a factor that must be consideredin wind farm placement. Theseimpacts have been used as anargument against wind farm development in some areas.

In most areas that have been studied, wind farms do not havea negative impact on property values. However, these studies areall relatively short-term.

Biomass:

carbon-neutral (ideally) – land use concerns

combustible renewable wastes - ~10% of total world energy production

wood waste

landfill gas

municipal solid waste

manure biogas

waste cooking oil – biodiesel

cropland biomass – ‘energy plantations’

fast-growing tree/grass species – willow, switchgrass

biodiesel – oil seed crops

ethanol – corn, wheat

algal biomass

Biomass – concerns

biofuels

competition with food crops

degree of carbon-neutrality

soil degradation

cropland and forest biomass

monoculture – pests, loss of bioodiversity

loss of habitat

land use changes