Sustainability | Renewable Energy

GCT Featured Articles

How Safe & Clean is Nuclear ☢️ Energy?
By Daniel 2021/08
Nuclear – necessary energy
By Daniel 2021/07
Austin, Texas: a sustainable city
By Daniel 2021/03
Europe’s greenest city district
By Daniel 2021/02
Profiles in Sustainable Cities – San Diego, California
By Daniel 2020/11

GREEN Energy

Sources of renewable energy include: hydroelectric energy (and hydrokinetic energy), wind (onshore and offshore), biomass (and biofuels), solar (PV and solar thermal technologies), and geothermal.

For reference, below is the 2020 Lazard‘s LCOE chart - showing that renewable energy (especially onshore wind farms and utility-scale solar) is becoming more affordable, and is now priced below ALL fossil fuel energy sources.

On the 2020 LCOE chart, it’s renewable energy sources (especially onshore wind farms and utility-scale solar) with the best overall price of all energy sources; and wind energy and utility-scale PV are now priced lower than coal, and onshore wind and utility-scale PV are now even cheaper than gas combined cycle (when the full LCOE is taken into account)>>> 

Lazard's 2020 LCOE
Lazard‘s 2020 levelized cost of energy (LCOE)

Shares of renewable energy throughout the world

Solar farms, wind farms, hydroelectricity, and other hydrokenetic projects, biomass plants, and geothermal energy projects - along with energy storage - have the potential to deliver much of the world's energy needs- depending on how much investment these renewable energy (RE) sources receive. Renewable energy sources currently account for over ¼ of the electricity generated in the global energy mix, as an overall rough average between all of the above RE sources combined (although that figure could more than double by mid-century - see the chart from BNEF below).

In its World Energy Outlook, the International Energy Agency identifies pathways for clean energy technological solutions needed to reach global carbon neutrality (i.e. net zero GHG emissions) by 2050. It also details interim goals that will ensure the world is on the path to carbon neutrality. In order to achieve these goals, by 2030 low carbon sources (the majority of which will ultimately be renewable energy sources) need to generate 75% of the world's energy, up from 40%.

Many European countries; especially Northern European nations; led by Iceland, Germany, Denmark, Norway, Sweden, and the United Kingdom - have a large share of renewable energy production in their energy mix. Most countries throughout Europe have significant development of renewable energy technologies and substantial generation from RE sources.  Dropping prices for renewable energy, and favorable public policies for renewables, have seen the share of renewable energy generation take the lead in energy production in many countries throughout Europe.

Many Latin American countries produce a significant amount of renewable energy, a little less than ⅓ as an overall rough average of the majority of Latin American countries' overall energy mix; though some countries in Latin America produce much higher shares of renewable energy. China produces around ¼ of its energy from renewable energy sources for its energy mix; while India produces less than 20% of its energy from renewables. The United States, Mexico, Australia, and Japan, all hover at roughly 15% energy generation from renewables in each of their country's energy mix.

However, it must be noted that the amount of renewable energy generation varies widely from country to country, and from region to region within countries. States and provinces within countries have wide variations of renewable energy generation as a share of a country's energy mix, and have varying mandates for future renewable energy production. For example, in the United States, California produces over 40% of its energy from renewable sources, and is under a statewide mandate to get 100% of its electricity (100RE) from clean energy sources by 2045.

The whole of the United States generates only about 17% of its electricity from renewable energy sources; despite many states having renewable portfolio standards that require those states to generate a certain amount of their energy from renewables. Meanwhile, the U.K., Denmark, France, Sweden, and New Zealand, among other countries, have mandated their countries reach carbon-neutrality by mid-century (Sweden aims to be net zero emissions by 2045), in large part by the use of renewable energy.

Bloomberg New Energy Finance (BNEF) sums up the projected rise of solar and wind in the below chart. Other RE is also expected to expand, save for hydroelectricity, which is projected to fall. Below are a few of BNEF's top-line takeaways from their energy outlook to 2050>>>

Global power generation mix (Source: BloombergNEF)

"1. Wind and solar make up almost 50% of world electricity in 2050 – “50 by 50” – and help put the power sector on track for 2 degrees to at least 2030.

2. A 12TW expansion of generating capacity requires about $13.3 trillion of new investment between now and 2050 – 77% of which goes to renewables.

3. Europe decarbonizes furthest, fastest. Coal-heavy China and gas-heavy U.S. play catch-up.

4. Wind and solar are now cheapest across more than two-thirds of the world. By 2030 they undercut commissioned coal and gas almost everywhere."


Sources of Renewable Energy


Grand Coulee Dam, Washington state
Grand Coulee Dam, Washington state

The largest single source of renewable energy worldwide is hydroelectricity, mostly from hydroelectric dams. Hydropower represents a significant portion of total overall world renewable energy production- about 60% of the world's renewable energy production is hydroelectricity. About 16% of the world's electricity needs are met by hydroelectricity (mostly in the form of hydroelectric dams).

In the United States, renewable energy represents under 20% of the total energy production and consumption as an overall average of all 50 states; though Washington state gets over 90% of its energy from hydroelectricity alone. In the United States, renewable energy represents approximately 17% of total U.S. electricity production; while over 35% of renewable energy production in the U.S. comes from hydroelectricity (mostly dams), and hydroelectricity represents over 6% of total U.S.electricity generation (as a total average when all the states are factored in).

Dams can easily be installed in almost any waterway, including rivers in remote rural areas. A higher reservoir (water from a river, lake, or other waterways) is let through a hydroelectric dam by the dam's operators when it's time to generate electricity. The kinetic energy of the water flowing through the dam turns turbines, which generate electricity. Dams, both large and smaller scale, produce some ecological problems, and require constant maintenance.

Dams do tend to result in large reservoirs of stagnant water, erosion of wetlands, and erosion of areas surrounding the dam, along with other problems for the local ecosystems downstream from where dams are developed. These ecological problems caused by hydroelectric dams can be mitigated with ecological remedies implemented by the dams' developers and operators.

Freshwater tidal energy; as well as ocean waves, currents, and tides, also represent dynamic, abundant sources of renewable energy. Hydrokinetic systems are in use in freshwater lakes and rivers throughout the world today. These RE sources are environmentally friendly; as long as care for the affected ecosystems is implemented and maintained by the RE developers.

The most common types of these freshwater hydrokinetic systems include tidal barrages and tidal stream generators. Ocean sources of hydropower remain in the research and development phase, and have reached the demonstration phase for a few projects worldwide...

Please see:

Hydrokinetic and Marine Power


Biglow Canyon Wind Farm in Sherman County, Oregon
Biglow Canyon Wind Farm in Sherman County, Oregon

Wind power is generated with the conversion of energy by wind turbines into electricity (the kinetic energy of wind turns electricity-generating turbines). Wind farms are installed on uninhabited land, unused dessert land, agricultural land, or offshore (most offshore wind farms are currently in Northern European countries). Wind farms have some of the lowest environmental impacts of all large-scale renewable energy sources. Large-scale wind farms are much more common than units for individual homes. Smaller wind turbine units are increasing in production, however, and are capable of powering anything from large appliances or generators, to RVs, to entire buildings; depending on the size of the turbine.

Please click & read:

Breakthroughs in wind energy technology

London Array – paving the way for efficient offshore wind energy farms

Anholt Offshore Wind Farm — Denmark’s most powerful source of renewable energy

The Block Island Wind Farm – America’s ONLY operational offshore wind farm

It must be noted that employment opportunities in clean and renewable energy, especially wind and solar are consistently growing; while the cost of RE is decreasing, and the efficiency of clean energy continues to increase.

Solar farm, southeast England
Solar farm in southeast England

Photovoltaic (PV) solar power entails harnessing the sun's energy to directly produce electricity by converting sunlight into electricity through solar PV cells (the "photovoltaic effect"). New solar technologies are developing at a rapid pace, bringing solar closer to cost parity with fossil fuels (rooftop solar), or below the cost of most fossil fuel energy (utility-scale thin-film solar).

Solar cells are becoming more efficient, thinner, smaller, transportable, flexible, and even spray-on, allowing for easy installation, use, and efficient energy production. Solar PV cells, solar panels, solar micro-grids, and solar farms, have been used to power a wide range of applications.

Solar technologies are used in everything from the calculator powered by a single solar cell, to off-grid homes powered by an entire photovoltaic array; to solar farms powering thousands of homes and buildings in a city. Large-scale, or mega, solar farms are growing in deployment worldwide. Concentrated Solar Power (CSP), solar towers, dishes and troughs, are all growing sources of renewable energy.

As opposed to PV, which directly generates electricity, solar thermal uses solar energy indirectly, to heat a working fluid. Solar thermal, including CSP and solar water heaters (among a few other forms of solar thermal), uses technology (generally special mirrors for solar energy creation - heliostats) to harness the sun's energy; but then that energy heats a working fluid, which is ultimately used to generate electricity (traditionally the energy production takes the form of steam that turns turbines, as in many other forms of energy generation).  One benefit of solar thermal is that a few forms of energy storage are readily available when this form of renewable energy is employed.

Please click & read:

Recent breakthroughs in solar photovoltaic and solar thermal technologies

Community solar and net metering – pushing renewable energy forward

Ivanpah Solar Electric Generating System

The 550 megawatt Topaz Solar Plant


Biomass/ biofuel sources include: agricultural by-products, forestry remnants, and organic matter such as wood chips, peat, sawdust, and bark; crops like corn, sugarcane, wheat, soybean; and plants like switchgrass, palm, sorghum; and also various types of algae. Biomass includes biodegradable wastes that can be used as fuel (biofuel- biodiesel, and ethanol). Biomass can produce energy for a municipality in a biomass power plant, just be converted into biofuel, or even power a farm (see link to anaerobic digestion below).

Biomass/ biofuel can be derived from numerous types of organic cellulosic and non-cellulosic plants, in addition to waste (garbage, agricultural waste, forestry remnants, etc...). Wood and plants are abundant sources for biomass; but also agricultural, farm, and even municipal and household waste are good sources for biomass production.   Many varieties of plant species can be used for biomass/ biofuel production, however, algae is a very promising biomass source. Algae are among the fastest-growing plants in the world, and as much as 60% of their weight is plant-based oil - making algae a potent source for energy generation.

Please see:

Algae- the future of biofuel

Anaerobic digestion - a proven solution to our waste problem

Cellulosic biofuel - fuel solutions


Geothermal power also has small and large-scale designs. Geothermal heat pumps, on the small end of the spectrum, are less common than industrial plants. Geothermal plants are located near natural energy sources; tectonic plate boundaries, volcanoes, hot springs, and geysers. Geothermal energy is primarily power generated from natural steam and hot rocks, magma, or lava which heat water in the earth's crust. The majority of geothermal power is produced by conveying heated water or steam back to the surface so that its heat can be extracted through a heat exchanger, or its pressure can be used to drive turbines. An example of an are of the world rich in geothermal energy potential, production, and use is Iceland.

Please see:

Geothermal district heating in Iceland

Of course, there are a few other potential renewable energy sources, including forms of kinetic renewable energy and futuristic RE ideas not mentioned above. Other types of renewable energy include, most notably, hydrogen and hydrogen fuel cells,. Hydrogen can potentially, eventually, be used to help meet the world's energy needs. In some European countries, hydrogen fuel cells are being used efficiently in public buses.

More R&D is needed for the rest of Europe, the USA, and Australia (among other countries in Asia and elsewhere that have shown an active interest in hydrogen fuel cells), to use hydrogen/ hydrogen fuel cells efficiently and effectively as a major energy source. However, there are already significant hydrogen fuel cell bus projects in some European countries.


GCT Featured Articles

Clean Hydrogen Power

Hydrogen and the Clean Energy Transition |  Hydrogen is one of the most promising emerging energy technologies to fill...

Read Post

Deforestation and solutions; including reforestation Deforestation of our planet, for centuries, has led to issues such...

Read Post

UN Framework Convention on Climate Change (UNFCCC) – Conference of the Parties |  World leaders, dignitaries,...

Read Post

One Comment

  1. Please let us here at Green City Times know what you think in a comment; and we’ll try and answer any questions as well.

    Please also visit our other blog at

    [Dan Braff is the founder of GCT –

    Daniel Braff]

Leave a Reply

Your email address will not be published. Required fields are marked *

two × five =