Chapter 20c Conventional Energy Alternatives

Hydropower has three advantages over fossil fuels:

- It is a completely renewable source of energy. - Hydropower is efficient, with an EROI ratio of more than 80:1, which is higher than any other modern energy source. - No carbon dioxide or other pollutants are emitted.

Negative impacts of hydropower include:

- Natural riparian habitat is flooded upstream of the dam and deprived of water downstream of the dam. - suppression of flooding prevents river floodplains from receiving nutrient-rich sediment from the river. - Dams cause thermal pollution if the river downstream is kept artificially shallow and it warms rapidly - Thermal shocks can occur if cold water is suddenly released from the dam's reservoir - the passage of fish and other organisms through the river is blocked

Biodiesel has many advantages:

- less vehicle emissions - nearly identical fuel economy - cost effective - nontoxic and biodegradable - can be sourced from food waste

What plants grow quickly enough that they can be cultivated specifically for generating biopower?

bamboo, fescue & switchgrass

Why is biopower better than fossil fuels?

because it is cleaner, contributes less to climate change, & is generally more sustainable than burning fossil fuels - burning biofuels has the side effect of depriving soil of the nutrients it would receive from the natural decomposition of plant matter

Hydropower has less room for expansion than other alternative energy sources...

because most of the world's large rivers have already been dammed - newer renewable energy sources have a much greater potential for future growth

Many species of algae are now being cultivated to produce

biodiesel, ethanol, or even jet fuel

Waste products from logging, sawmills, pulp mills & paper mills can be used as a source for

biopower

In rural regions of developing countries, people heavily depend on fuelwood to...

burn in their homes for heating, cooking, and lighting, which can lead to deforestation, soil erosion, & desertification

Biomass energy use can cause Health issues

burning wood & waste indoors for cooking on traditional stoves produces more smoke than heat. can cause lung diseases

flexible fuel vehicles

can operate on a mix of 85% ethanol & 15% gasoline - this is especially popular in brazil, which generates ethanol by fermenting crushed sugarcane residue

photobioreactors

closed transparent tubes that algae can be grown at a large scale in outdoor ponds

co-firing

combining biomass with coal in existing coal-fired power plants to generate electricity

Biomass

consists of organic material derived from living or recently living organisms, and it contains chemical energy that originated with sunlight and photosynthesis

A biogas plant in the Swedish City of Kristianstad takes in

forestry waste, crop waste, garbage and food waste & uses it to generate biogas - the biogas is used to generate electricity and to heat homes

In developing countries, bioenergy is used to produce biopower, which is

generating heat & electricity - liquid biofuels may also be generated from bioenergy

Pumped storage

hydropower works by transporting water from a lower reservoir to a higher reservoir during times when demand for power is weak and prices are low - when demand is high again, the water is allowed to flow back downhill through a turbine

biodiesel

is a fuel produced from vegetable oil, used cooking grease, or animal fat.

Bioenergy

is energy derived from biomass.

Ethanol

is produced by fermenting biomass, generally from carbohydrate-rich crops, in a process similar to brewing beer

To replace all the automotive fuel used in the US w/ ethanol from corn, the nation would need to expand its corn acreage by

more than 4 times

biomass energy can cause environmental issues

people cut down trees in an unregulated manner, without being accompanied by reforestation to replace the lost forests, leading to widespread deforestation

Growing corn to produce ethanol intensifies...

pesticide use, fertilizer use, freshwater depletion, energy use, & other impacts of industrialized agriculture

cellulosic ethanol

produced by using enzymes to produce ethanol from cellulose

In principle, energy from biomass is carbon-neutral...

releasing no net carbon into the atmosphere. -burning biomass releases carbon dioxide that was recently pulled from the air by photosynthesis - the only holds true if forests, which sequester carbon dioxide, are not cut and used as a source of biomass

In principle, bioenergy is...

renewable and releases no net carbon dioxide into the atmosphere. - any carbon released had been absorbed in the production of the biomass

Biomass combustible waste chart

slide 10

top producers of hydropower chart

slide 25 !!

Sources and uses of bioenergy

table located on slide 3-4

Run-of-river

technique diverts a portion of the river's flow through a pipe or channel, passing it through a powerhouse, and returning it to the river - this is much less disruptive of the river's natural flow, but does not generate as much power

Biogas

the anaerobic bacterial breakdown of waste in landfills, which produces methane that can be captured and sold as fuel

The amount of electricity generated by hydropower plants is dependent on what?

the volume of water and the distance that it falls

Most hydropower plants uses the storage technique

this involves storing and releasing water through a series of turbines in a dam

Hydroelectric power (hydropower)

uses the kinetic energy of flowing river water to turn turbines and generate electricity

We harness bioenergy from many types of plant matter, including...

wood from trees, charcoal, & crop residue, as well as from combustible animal waste