What is Tidal Energy?

What comes to mind when thinking of renewable energy resources? Wind? Solar? How about tidal energy? Tidal energy is not commonly thought of when considering the types of renewable energy resources even though it is one of the oldest forms of renewable energy. Tides are caused by the moon’s gravitational forces.

Tidal energy is a form of hydropower that relies on the rising and falling of the sea levels and tidal energy devices convert the energy gained from the tides into electricity.

Tidal energy can be captured through a variety of ways. Surface devices lay on the ocean surface and capture electricity through the movement of waves. Underwater devices consist of a vertical or horizontal turbine, similar to that of a wind turbine, which creates electricity as the tide moves through the turbine. Reservoirs collect water and electricity is created as the water moves out of the reservoir through turbines. Tidal energy is most efficient when the height, mass, and speed of the water are at their optimum level.

The different varieties of tidal technologies indicate how the electricity from the tidal energy is harnessed. Tidal barrages are similar to dams in that once the reservoir is filled, the turbines spin to create electricity. Tidal turbines are individual turbines that are placed in an area with a strong tidal flow where electricity is created when the water moves through the turbine, and tidal fences are a line of tidal turbines.

Turbine under water (NASA)

Tidal turbines generate electricity (NASA)

Tidal energy is the most reliable source of renewable energy because of the continuous change in tidal movements that occur twice a day from the moon’s gravitational force. Tidal energy runs 24 hours a day, 7 days a week, 365 days a year.

Another benefit to tidal energy is that it does not produce any form of pollution. It also does not require any use of nonrenewable resources, such as oil, to power the technology. Tidal energy even has an 80 percent success rate when converting to electricity.

Unfortunately, very few coastal countries are using tidal energy because it can be very expensive, and it can interfere with marine life. The cost for tidal energy can be anywhere between $1.3 million to $1.8 million. Also, a country must be on an ocean coastline to reap the benefits of tidal energy.

There are incredible benefits to using tidal energy despite the drawbacks and high cost. As tidal energy technology begins to advance, the cost of incorporating tidal energy as a renewable energy resource in countries will decrease. It is important to incorporate all forms of renewable energy resources into countries in order to combat the effects of climate change.

Have you joined #YALIGoesGreen yet? Visit yali.state.gov/green/ to learn more.

Reducing time and cost of renewable energy

We have all heard about the importance of reducing our carbon footprints and choosing to go green. However, the two main arguments people have for choosing not to go green are “I do not have time” or “I cannot afford it.” Time and money are inconveniences that have influenced individual behaviors to not go green.

The main benefit of going green is reducing your carbon footprint which is the amount of energy you consume. Making a few simple changes to your daily life helps decrease your carbon footprint. Here are a few lists that show you how.

Saving time

There are ways that choosing an environmentally friendly alternative can save you more time and money. Here are a few ways in which you can save time while going green:

Saving money

When you reduce energy usage in and out of your home, you can save money simultaneously. Save money while going green by:

There are also alternative low-cost purchases that will save money in the long term:

These time and money saving options are attainable and help change your energy consumption habits. They will also help reduce your carbon footprint while beginning your journey to go green.

Have you joined #YALIGoesGreen yet? Visit yali.state.gov/green/ to learn more.

Japan joins Power Africa, with a focus on geothermal technology

A campaign to double access to electricity in sub-Saharan Africa just got a boost.

Japan has joined Power Africa, an initiative President Obama announced in 2013. Japan has committed to bring 1,200 megawatts of power online. As part of its agreement, Japan will work with African governments to develop renewable geothermal power, which is heat derived from the Earth.

In East Africa’s Great Rift Valley, where two of the Earth’s tectonic plates are slowly pulling apart, geothermal energy is low-cost, and low in carbon emissions.

Two government officials signing papers (Eric Onyiego/Power Africa)

Seiji Okada (right) of the Ministry of Foreign Affairs of Japan signs a new partnership with Linda Etim of USAID to join Power Africa. (Eric Onyiego/Power Africa)

More than 100 private-sector partners, host governments and multilateral organizations are participating in Power Africa. The goal is to help the estimated two out of three people in sub-Saharan Africa who currently lack electricity.

Japan’s partnership in Power Africa also helps the world make progress on the United Nations’ Sustainable Development Goals, including ensuring that all people have access to affordable and clean energy by 2030.

Japan’s decision “sends a strong message to African people that our governments are taking the issue of energy poverty seriously,” said Seiji Okada, Japan’s ambassador for the Tokyo International Conference on African Development.

Building social currency for climate leadership

By Max Thabiso Edkins

We are living in an exciting time. We know climate change is real; we feel impacts every day. But we also know what we need to do to tackle it. To quote the U.N. Secretary General Ban Ki-moon: “We are the first generation that can end poverty, the last that can end climate change.” I want to focus on the fact that we can solve climate change.

Global leaders have spoken up! In the hottest year on record, in 2015, we finally reached global unity with the presentation of the Paris Climate Change Agreement. It was the fastest ratified agreement under the U.N. to date! And this year, after the Agreement entered into force, the urgency for climate action was present at COP22 in Marrakech.

And even so, we still see global greenhouse gas emissions rising.

To bend the emissions curve, we need a global movement. We need to trigger the emotions in our global society in support of climate action. We need to make climate change relatable and tangible. And there is no better way of doing that, than by communicating the opportunity in climate change.

I am optimistic because climate change offers an opportunity for a transition to a low carbon and resilient future. This is the opportunity of our generation to find our purpose and to build the future we want for us and for generations to come.

In creating climate opportunities it is important to direct these to those most affected. We cannot leave anybody behind because climate change is also a justice issue. Those already having to move homes because of sea-level rise or extreme weather events, or those losing their jobs in the fossil fuel industry, all need to become a part of the solution. Our research at the World Bank shows that an immediate push on climate-smart development can keep more than 100 million people out of poverty.

I am optimistic because I have a 9-month old son, and when he grows up the world will be a different place. I can see a future where homes and villages in Africa will be powered by solar panels on their roofs, where fossil fuel companies have transitioned to being energy companies with diverse portfolios of renewable energy, where mobility is largely electric, where our consumption patterns are in line with our global carrying capacity, where our forests are preserved and urban spaces are made green, and where there is a price on carbon and the economics favours green growth.

And we are already building that future. In South Africa we have seen a renewable energy revolution with more than 30 operational projects and with plans of almost 38GW of wind and almost 18GW of solar in the latest Integrated Resource Plan (IRP) for Electricity. And, for me, the headlines coming out of the IRP are that new wind and solar projects produce the cheapest electricity. This is the headline we need to spread! At the Energy21 workshop we heard from South Africa’s Council on Scientific and Industrial Research (CSIR), that the cost of wind and solar in South Africa are estimated at 4.4 U.S. cents per kilowatt hour, one of the lowest costs around the world.

Around the world, solar and wind are taking off at exponential scales. All projections of installed capacity made in the early 2000s are being shattered by 14 times for wind and close to 60 times for actual installed solar in 2015. Some see our Climate Action Agenda, to decarbonize our economies, as the biggest new business opportunity in the history of the world. here are the facts:

More than ever we are aware of what is happening around us. Our interconnected lives through the digital age allow us to see and feel the changes around the world. This is helping create the movement that will define our time.

I am optimistic because we are a collective species, and we know that tackling climate change will take a collective effort. There is no silver bullet, but we all need to do what we can in our own spheres of influence. Be a climate leader in your own right. Biology has taught us that natural selection is not necessarily survival of the fittest individual, but survival of the fittest community.

Climate change is our species test, our chance to show that we are able to live in harmony with our world.

I am optimistic because Young People are leading the call for climate action and are spearheading the global movement. In 2014 more than 400,000 marched in New York, in 2015 they rallied in support of the Paris Agreement, and this year young filmmakers sent their message to COP22. We, Connect4Climate, ran the Film4Climate Global Video Competition, receiving 860 submissions from 155 countries, which presented a clear global call for climate action. The stories are of women-led bio-charcoal solutions in West Africa, of pay-per-use solar-entrepreneurs in Haiti, of electric vehicles and a desire to reduce meat consumption and protect our forests.

Overall it became clear that young people today want to be a part of the solution. They want jobs in the new climate economy. They want to see our economy transition and they want to be an active part of it. They find clean tech and low-carbon technologies exciting.

The average age in the Control Room during the Apollo Lunar Landing Mission was 26 years old! If young people helped bring us to the moon they will lead our energy revolution. Africa is the youngest continent in the world with a median age under 19 years. Let this be an opportunity to drive the narrative and economy for a renewable future.

Coming out of the Paris Agreement there is a real sense of optimism, that together we can shift our global emissions projection and build a more resilient future.

This is an exciting time, and I am excited to be a part of it. Like every great moment in history, today we are changing our world, and we will be remembered for it. Together we can build the social currency for our leaders to act on their commitments. We can prevent dangerous climate change!

I would like to thank you all for your commitment. Thank you for your energy. Thank you for building the low-carbon resilient future we need.

In closing let me emphasize that your will to act is in itself renewable energy.

Max Thabiso Edkins is a Climate Change and Communications Expert at the World Bank’s Connect4Climate Program. Connect4Climate is an Energy21 partner organization.

The promise — and importance — of energy storage

Most people know that batteries store electricity — in our cameras, cars and portable laptops. Now batteries are used to store energy on a larger scale — for buildings powered by rooftop solar or wind installations, and on the electrical grid.

But high-tech batteries are just one type of energy storage. More than 200 companies from around the world are looking at new ways to store energy, energy expert and entrepreneur Bartosz Wojszczyk says.

What does energy storage have to do with you? For one thing, it can ensure that when you flip on a switch, the light works.

Storage technologies are important pieces of the energy transition puzzle not only because they can stockpile electricity for use later, but because they help stabilize the flow of electricity, especially as intermittent power sources such as solar and wind enter the network.

“New renewable and clean energy technologies that are coming in at reasonable prices are driving us from that traditional model, where we have a big centralized plant that provides electricity through transmission lines to our homes,” says Charles Hanley, who manages grid modernization, energy storage, distributed energy resources and other programs for Sandia National Laboratories in Albuquerque, New Mexico.

Headshot of man in suit (Courtesy of Charles Hanley)

Charles Hanley is senior manager for the Grid Modernization Program at Sandia Labs. (Courtesy photo)

Thanks to solar panels and wind turbines, people can now generate their own electricity at home, or in places far from the power grid. That makes efficient energy storage essential.

“Storage will be more and more important to smooth out some of the variability that comes when the wind isn’t blowing, when the sun goes behind the clouds,” Hanley says.

Solar energy technologies can generate a lot of electricity during the daytime, although peak electricity demand often occurs later, when people come home from work and school. That’s when they turn on lights and turn up the heat in winter or the air conditioners in the summertime. If that daytime energy is stored, it can be used later when it’s needed and more valuable.

Row of power boxes (© AP Images)

Inverters provide battery backup and are one of the technologies used to store energy from solar or wind at small businesses and homes. (© AP Images)

A number of technologies are already in use: various types of batteries, hydropower and thermal energy storage, to name a few. But scaling these technologies to meet demands of power grids is still daunting and costly.

More research and development is needed on affordable, efficient storage technologies.

Fortunately, big businesses are investing in energy storage research and development. Wojszczyk says the energy storage market is set to expand dramatically, citing the Boston Consulting Group prediction that the energy storage market will be worth up to $400 billion by 2020. That includes grid-connected, non-grid-connected and different applications.

That investment should eventually bring affordable storage technologies to the marketplace. That’s what happened with solar and wind technologies. Those prices have dropped significantly in the past few years.

Two computer screens on a desktop (© AP Images)

Virtually monitoring the flow of electricity to and from the energy grid is integral to new systems for storing and distributing energy. (© AP Images)

But Hanley says it’s important to remember that, along with manufacturing batteries and other energy storage tech, “the system that goes around them” is critical. That includes advanced power electronics: technologies — some under development — that can regulate voltage and respond to fluctuations, and other controls and dispatching tools to supply safe, reliable electricity, whether it goes to a national power grid or to businesses, homeowners or communities that have their own distributed energy resources.

“We are going through a transition in terms of energy technologies and our whole energy infrastructure,” Hanley says.

Solar energy comes in big and small packages

We all know the sun warms us, it gives us light during the day and it makes plants grow. On top of all its natural benefits, it is now an important source of electricity.

Does the sun’s light make electricity, or is it the sun’s heat?

The answer is both. Different technologies capture light or heat to generate power. It may be done on a large or small scale, so homeowners, small businesses and power companies that run utility-scale solar farms can all perform this magic if they have the right tools.

Here’s a look at the different kinds of sun power and how they are used.

The basics

The sun’s power may be tapped for energy passively by locating buildings to make the most of the sun. Good sun exposure, construction materials that capture the sun’s heat, windows that maximize sunlight, built-in natural air circulation — all take advantage of physical surroundings.Passive solar architecture makes the most of the sun and breezes. The new Abdali Mall in Amman, Jordan, utilizes solar energy to light, heat and cool.

A black container full of water hung out in the sun is an example of using passive solar energy techniques to heat water. How long the water will retain the heat depends on how big the container is, but it will stay warm for a while after the sun sets.

Active solar power involves more machinery — sophisticated technologies such as solar photovoltaic panels (PV) and concentrated solar power (CSP).

Solar PV: electricity directly from sunlight

Solar photovoltaic panels are versatile, because they may be used on individual houses and commercial buildings as well as on large solar farms. Materials with a special ability to convert the sun’s rays into electricity are the core “cells” of solar PV panels.Solar photovoltaic panels can be placed in large or small arrays. Solar photovoltaic film and paint are even more versatile.

Solar panels can provide electricity to off-grid sites or feed electricity into the general power grid. A small solar panel can supply enough energy to power a few lights or a laptop in a place not connected to a power grid.

An array of panels installed on a rooftop can provide much of the electricity needed on-site — even after the sun goes down, if energy-storage batteries are used. Where power grids are equipped to accept it, excess electricity can be a moneymaker for small producers using distributed energy resources like solar. Residences and businesses alike can benefit. Some sports arenas generate enough electricity from solar to power hundreds of homes in nearby neighborhoods.

A huge solar PV farm can power entire towns. Among the largest such projects currently online are the Topaz and Solar Star plants in California, both run by MidAmerican Solar and each having 580 megawatts generation capacity. NRG Energy operates the Agua Caliente solar project in the desert in Yuma County, Arizona, with a 290 MW capacity. Other, even larger, facilities are in construction or planning stages around the world.

Concentrating solar power (CSP): Electricity from solar heat

CSP uses solar thermal energy indirectly by focusing the sun’s heat into a small beam. Thousands of mirrors concentrate beams of solar heat on boilers. The heat produces steam that runs turbines generating electricity. CSP also has expanded electricity-storage potential.


The SolarReserve Crescent Dunes plant in Tonopah, Nevada, is the first to commercially use a molten salt storage technology. The Redstone thermal power project in South Africa’s Northern Cape province, using the same technology, is slated for completion in 2018. Molten salt storage can extend the availability of solar energy to customers as long as 12 hours.

As prices, particularly of solar PV technologies, fall and more renewable energy resources integrate into conventional power grids, more polluting fossil-fuel-powered electricity can be replaced by clean energy.

'Blue energy' could be another way to go green

A simple way to produce a lot of energy could be found anywhere a river meets the sea.

Researchers call it “blue energy,” and it could be the next frontier in clean-energy technology.

Osmosis occurs when salty water hits freshwater across a permeable membrane. Salt ions (molecules with an electrical charge) will pass through the membrane until the amount of salt is equal on both sides.

“Making use of the osmotic pressure difference between freshwater and seawater is an attractive, renewable and clean way to generate power,” explain researchers at École Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland, who collaborated with researchers at the University of Illinois.


The researchers wondered if they could figure out how to capture that electrical charge as it moved across the membrane separating the fresh and salty water. They did it by creating two tiny membranes, just three atoms thick, made of molybdenum disulfide, which is plentiful and easy to produce. Then they made a tiny hole in the membranes and let osmosis take over and push the electrically charged salt ions through this tiny hole, called a nanopore.

EPFL’s research is part of a growing trend. Scientists around the world have been developing systems that leverage “osmotic power” to create electricity. Projects are underway in Norway, the Netherlands, Japan and the United States, the science news site Phys.org reported.

This article draws on a report from the Voice of America.

Solar energy lights the way from California to Africa

California is blazing ahead in renewable energy, with an emphasis on solar. It’s an ambitious plan that other U.S. states and countries are watching carefully.

The state can already electrify 3.3 million homes with solar energy alone. A large chunk of that comes from the new Solar Star installation, with 1.7 million solar panels. It is the solar farm with the largest capacity in the world.

California outshines all other U.S. states in solar power. The solar dominance was achieved by a combination of local, state and federal laws and incentives for businesses and ordinary citizens to adopt solar and other renewable energy technologies. Generous tax credits have been important tools in California’s renewable energy roll-out.

California installed more solar in 2014 than all the other U.S. states combined from 1970 to 2011, according to the Solar Energy Industries Association.

California leads the top 10 U.S. states using solar power. (State Dept./ J. Maruszewski)

California leads the top 10 U.S. states using solar power. (State Dept./ J. Maruszewski)

The state has long led the charge into a renewable energy future, and it continues to build on that record. State climate legislation enacted in 2015 mandates that 50 percent of California’s electricity must come from renewable sources by 2030. This means utility companies are grappling with a new, 21st-century business model. Renewable energy from numerous sources — called the distributed grid — will soon provide as much or more power than the conventional, centralized grid. It’s a big change.

New York, Vermont and Hawaii are among those states with similar ambitions. Hawaii aims to be 100 percent renewable by 2045.

And it’s happening around the world. Clean energy investment has been a priority in China, Europe and Brazil, just a few of the places expanding their solar, wind and geothermal energy capacities.

South Africa, for example, has a number of solar energy projects underway. In May, Eskom, the country’s state-owned power utility, signed a 20-year power-purchase agreement with the Kathu Solar Park. That project alone will add 100 megawatts to the national grid by the end of 2018. Kathu Solar Park will use innovative thermal storage technology. When it comes online, it is expected to supply 80,000 households across South Africa, reduce carbon emissions by 300,000 metric tons annually and bring 1,200 new jobs.

What is the power grid and how does it work?

Everybody’s seen those tall towers strung with wires that stretch across the landscape. Most people know that those are power transmission lines, but they may not know they are looking at part of the power grid.

First you need electricity …

Illustration of wind mill, oil barrel, and a flame (State Dept./Doug Thompson)

(State Dept./Doug Thompson)

The power grid starts in the places where electricity is made. Once upon a time, electricity was generated only at central power stations, which usually ran off fossil fuels — coal or natural gas — or nuclear energy. Today there are more and cleaner options for energy generation. That’s a good thing, because fossil fuels release harmful greenhouse gases when they burn, which hasten global warming. And nuclear power plants use the metal uranium which, like fossil fuel, is nonrenewable and can be a dangerous environmental pollutant.

That’s why renewable energy is so important: Sun, wind and other renewable resources are inexhaustible and clean. They are also cheaper, because they generate electricity closer to home, which means fewer long power transmission lines and other expensive grid infrastructure.

Transmission and distribution

Illustration of power lines (State Dept./Doug Thompson)

(State Dept./Doug Thompson)

After electricity is generated, it must be transmitted and distributed to consumers. The network of transmission and distribution facilities makes up the power grid.

Typically, electricity is transmitted at a very high voltage over the power lines that dot the countryside. The higher the voltage, the less current needed for the same amount of power, and thus less loss of electricity (resistance to current in the lines creates heat that causes some loss).

When the electricity reaches customers’ neighborhoods, transformers convert the high-voltage electricity to a lower voltage for distribution to homes and businesses.

Consumers and “load”

Illustration of a power cord going into an electrical outlet (State Dept./Doug Thompson)

(State Dept./Doug Thompson)

When people use electricity for their lights, computers, appliances, heating and cooling they are drawing on the electrical grid. The total usage by customers is the “demand load,” which must be supplied by power providers. There are peak demand-load periods: at night when more lights are on, or the hottest or coldest times of day. Balancing those voltage loads is where power grid management becomes tricky, because the energy flow must be perfectly balanced at all times to provide exactly the right amount of electricity to customers.

Grid operators employ sophisticated mechanisms to increase or decrease power generation to match consumer demand. These mechanisms automatically monitor and dispatch electricity. This is “load balancing.” Electricity inputs from distributed energy resources are new power streams that grid operators are learning to integrate and balance with the demand load.

How renewables are changing — and charging — the grid

Small-scale distributed power producers — solar panels or wind turbines on or near homes or commercial buildings — generate electricity to be used on the premises. But if the grid is modern, or “smart” enough, these small producers can make money on their excess electricity.

Renewable energy technologies are changing power grids all over the world as the traditional centralized power grid is making room for energy innovations. The need to integrate distributed energy resources with the regular grid is spurring new ways to manage energy:

Microgrids distribute energy locally and can connect with the regular grid or not, depending on the circumstances. If there is a power outage on the regular grid, a microgrid fed by nearby distributed energy resources can keep the lights on. It can also be independent of any big power system — useful in remote areas because minimal infrastructure is required.

Energy storage technology helps integrate intermittent renewables such as solar and wind into the power grid, saving excess energy generated during daylight hours or on windy days for use later. High-capacity batteries and other sophisticated technologies have been introduced, and more are being developed.

“Smart” meters allow communication between the consumer and the utility company so the utility can monitor usage and be alerted to outages. Some smart meters can monitor the electricity generated by small-scale energy producers, so the excess energy they feed into the grid may be credited, to be claimed later when they need it.

The grid will continue to be central to the future energy system. According to a 2014 report by the GridWise Alliance for the U.S. Department of Energy, both central and distributed energy will be part of a grid that is more flexible — and smarter than it is now. Instead of supplying one-way electricity, it will allow power to flow both ways. And fewer people will be deprived of electricity, no matter where they live.