All posts by Lydia Odom

Development of solar fuel: Q&A with Dr. Jillian Dempsey

Assistant Professor Jillian Dempsey of UNC-Chapel Hill can make fuel with two ingredients: water and sunlight.

Dempsey’s research team is studying solar fuel in order to store the energy given off by the sun in an efficient manner. Below, she discusses what her team hopes to accomplish in the coming years through their research.

(This interview has been edited for length.)


Lydia Odom: What sparked your interest in solar fuels?

 Dr. Jillian Dempsey: When I was an undergraduate student I started doing research in a lab and that was one of the labs that was at the forefront of developing this technology. So I did research in this area when I was in college and I got really interested in it. When I went to graduate school I joined another lab where I could continue this research area. Then after that kept moving further and further into the field. It was just a really exciting area to be in as we think about the threats to our energy security and our global health. It’s a little scary to think about what happens if we don’t develop this technology, so that was a big motivating factor to go in this direction.


Odom: Can you explain, in layman’s terms, what you’re researching and what the goal behind your research is?

Dempsey: My research focuses on ways to capture solar energy and covert it into a stored form, specifically fuels. A lot of solar energy technologies that are currently available are things like solar photovoltaic, like solar panels. Those are great technologies, but obviously they could be a lot better because they’re expensive and their efficiency is not that great. But kind of a bigger challenge toward their widespread implementation is the storage. Solar panels generate electricity, but when the sun is not shining you’re not generating electricity, so how do you address that challenge?

My area of research is solar fuels, or artificial photosynthesis. What it is is using the energy of the sun to synthesize high energy density fuels. A great reason why it’s called artificial photosynthesis is because green plants are taking sunlight, water, and carbon dioxide and they’re using the energy from the sun to turn the carbon dioxide and the water into carbohydrates, or sugars, and oxygen. And when you generate these carbohydrates, that’s stored energy. So what we’re trying to do is something along those lines. We want to do a much simpler reaction, and instead of making sugars, which are complex molecules and require a PhD in organic chemistry to make, we want to do something simple like spitting water into hydrogen and oxygen … The splitting of water into hydrogen and oxygen is a endergonic reaction, so you have to put energy in to do that reaction and then the products are essentially storing the energy of the sun. And if you were to take that hydrogen and combust it, you would release all the energy … So we’re just trying to close that loop there. If the energy in to make hydrogen comes from the sun, then when we combust hydrogen we get energy back out.


Odom: In what form is the fuel you’re making? Is it a gas?

Dempsey: If you use it to make hydrogen, you are making a gas. Now that’s a challenge, because we like liquid fuels. So there are ways to couple this reaction with carbon dioxide… If you take carbon dioxide along for the ride there you could make products like methane or methanol. … But knowing that hydrogen is probably going to be an important fuel, there are a lot of people who have developed new materials for hydrogen storage…in order to make hydrogen a viable fuel.


Odom: Have you found anything in your research so far that may lead to this being a viable fuel?

 Dempsey: A lot of what my lab does is we study the very fundamental processes that are associated with building a device. So we’re not engineers, we have not built a device. But we think about how to make this process energy efficient. So imagine you are a catalyst and you take in sunlight. Now, sunlight has a certain energy, so every photon that hits the earth has a certain energy. We want to make sure we’re not wasting the energy that comes in in those photons. So what we’re trying to do is figure out ways that the catalysts won’t waste energy. We want to make sure that when they take the energy from that photon, they turn all the energy from that photon into fuel energy. We want to maximize that energy conversion process. We’re trying to work on the little details that make a big difference in the efficiency.


Odom: What are the main obstacles in scaling this up to be viable in the future?

Dempsey: A lot of the challenges with all solar technologies, this goes for the silicon solar panels we see now as well as the solar fuels, are the costs behind the materials that are needed to make these devices. One of the reasons we don’t see more solar panels is because of their high cost. And that comes from the materials needed and the processing for them. … A lot of what we have to do is figure out how to get cheaper materials, like nickel and iron, to behave like the expensive materials. Because not only are those materials expensive, part of the reason they’re expensive is because they are not very abundant on earth. They’re very rare materials. And they’re rare so their price goes up. But even if we had money, the fact that they’re rare means that we don’t even have enough of those materials on earth to fill the need.


Odom: What do you see as the main strength of this new technology, and why it might be able to overcome these obstacles?

Dempsey: There are a lot of advantages. It clearly addresses the storage issue. And also, because we’re making fuels, it addresses energy needs in the transportation sector. Another benefit of this technology is the fact that you don’t need to be on the electrical grid to utilize it. … In developing countries that don’t really have that electrical infrastructure but are rapidly becoming more and more developed and using more and more energy, this is a great opportunity for them. … And the last benefit I’ll note, is that you can start with saltwater or sewage waste water and make hydrogen. And then, when I release hydrogen though combustion or use hydrogen in a fuel cell, either way the product is clean water. So kind of the bonus is water purification.


Odom: Is there a time frame you see all of this happening in?

Dempsey: I would say maybe 15 to 20 years before this is something we’re seeing in the market. …People are being more optimistic than that and I am not as optimistic as other people, just because I’ve watched the process in 10 years very closely. So I know how far we can get in another 10 years, and that’s not enough.

Innovative solar energy on the horizon

Solar technology is emerging on all fronts.

Some critics find solar energy limiting, due to its bulkiness and intermittence. But revolutionary solar technology will challenge arguments against the use of solar as renewable energy. Look below for a list of existing solar technology and what it may become in the future.


  1. Solar photovoltaic (PV)

The sparkly solar panels you see on the rooftops of homes are typically solar PV. These panels work by converting light into electricity, known as the PV effect. Silicon is the element most commonly used in solar PV due to its abundance on earth and relative affordability.

Alex Wilhelm, founder and president of United Solar Initiative, works to install solar PV in rural regions of Nicaragua. He recognizes the benefit of the off-grid nature of solar PV in low-income communities.

“Accompanied with battery storage, solar panels enable communities to remain sustainable off the grid and are the simplest form of renewable electricity to install,” he said.

As opposed to developing countries, solar PV will likely be concentrated at the utility and commercial level in more developed nations.

Solar PV installed on a rooftop. (Photo by U.S. Army)
Solar PV installed on a rooftop. (Photo by U.S. Army)


  1. Thin film PV

As its name suggests, thin film PV is extremely thin—only one micron thick. To put that into perspective, human hair is about 75 microns. This makes thin film more lightweight and versatile than solar PV, and suitable for many surfaces, from rooftop shingles to clothing.

Thin film works similarly to solar PV, by converting photons into electricity. However, thin film cells can be made from three different elements: amorphous silicon, cadmium telluride, and copper indium gallium deselenide. Each of these elements has advantages and disadvantages and is being tested for viability.

Thin film solar used as shingles on a roof. (Photo by Tai Viinikka)
Thin film solar used as shingles on a roof. (Photo by Tai Viinikka)


3. Concentrated solar power (CSP)

Concentrated solar uses mirrors to direct sunlight to a central point, which heats a liquid and powers steam turbines to create electricity. These plants are large in size, which makes the desert a desirable location for them. Unfortunately, this technology has high upfront costs and requires access to water, which creates a catch-22 situation when locating plants in the desert.

The largest benefit of CSP is its ability to generate electricity overnight and store energy in the form of thermal energy.

Mirrors used for concentrated solar power. (Photo by Alex Lang)
Mirrors used for concentrated solar power. (Photo by Alex Lang)


  1. Perovskite solar cells

This type of solar technology is made from a particular compound that is usually made out of lead or tin. Perovskite solar cells were first created in the early 2010s, but have already achieved efficiency on par with thin film.

Dr. Wei You, a chemistry professor at UNC-Chapel Hill, noted two main issues with perovskite: the use of lead to construct them and their stability. He said perovskite cells tend to get easily damaged by water, which is a big waste of money and energy. He thinks stability is their biggest barrier, and that their efficiency will likely remain at 21 percent going forward.

Perovskite solar cells. (Photo by University of Oxford Press Office)
Perovskite solar cells. (Photo by University of Oxford Press Office)


5. Organic solar cells

Organic PV aims to provide energy that is abundant on earth, and potentially cheaper than other solar solutions. This technology uses non-toxic light-absorbing materials (dyes) and plastics instead of elements like silicon, which are found in traditional PV.

This type of solar is attractive because of its ability to do things that silicon solar cells can’t, such as being integrated into transparent surfaces, like windows.

You has studied organic solar for over 10 years.

“From 2005 to 2012 we were able to push efficiency from 5 percent to 10 percent,” he said.

You’s research team has achieved organic solar cells with 12 percent efficiency. While this is only half as efficient as silicon, You is hopeful that the efficiency and longevity of organic solar will continue rising, and increase in market share in the next decade.

Organic solar cell. (Photo by KIC InnoEnergy)
Organic solar cell. (Photo by KIC InnoEnergy)


  1. Quantum dots

Unlike traditional solar cells, quantum dots have the ability to absorb light from non-visible parts of the light spectrum. This makes quantum dots capable of absorbing energy all day, which refutes the argument that solar energy only works when the sun is shining.

Another unique feature of quantum dots is its potential to become “spray-on,” which would allow nearly any surface to create solar energy. There is also potential for quantum dots to be the most efficient solar technology yet.

Quantum dots range in color depending on size and the light they absorb. (Photo by Antipoff)
Quantum dots range in color depending on size and the light they absorb. (Photo by Antipoff)

Dope or Nope? Nuclear energy as alternative fuel

You probably don’t often think about nuclear energy, but maybe it’s time to take a deeper look.

Nuclear energy has been a controversial topic since its creation in the 1950s (think: Fukushima). But it now generates nearly 20 percent of the U.S’s total energy production, and will likely keep growing.

The important question now is: should the nuclear industry continue expanding?

Answering this question is tough, but in order to do so both sides of the argument must be examined. Is nuclear energy “dope” and a promising source for energy in the future? Or should the U.S. say “nope” and stop pushing nuclear altogether?


Dope! Keep nuclear coming

  1. Relatively small carbon emissions

Yep, nuclear plants can produce energy without emitting greenhouse gases. That’s a pretty big deal considering the pressure on countries all over the world to reduce carbon emissions. The only problem is lifecycle emissions.

While the production of energy itself is “green,” the steps involved in making nuclear plants aren’t. The Nuclear Energy Institute recognizes that the process of creating nuclear emits pollution in various stages. However, nearly all other forms of renewable energy generate emissions during their life cycles too.

The International Panel on Climate Change, known as IPCC, conducted a study of lifecycle emissions for all types of energy. They found that nuclear emissions are on par with lifecycle emissions from renewables, and are much less than fossil fuels. This indicates that nuclear energy could become a major replacement for traditional fossil fuels.

However, nuclear engineer and associate professor Nam Dinh of North Carolina State University favors an “all of the above” approach.

“By itself, nuclear energy cannot replace fossil fuels,” he said. “Other renewable energy technologies have become increasingly affordable and should be pursued aggressively. However, wind and solar have their limitations.”


  1. Ability to generate huge amounts of energy

 One of the biggest criticisms of renewables is their inability to generate large quantities of energy. But this is not the case with nuclear.

Nuclear power is fueled by an element called uranium. A single pellet of uranium, slightly bigger than a pencil eraser, is the energy equivalent to a ton of coal. This translates to 17,000 cubic feet of natural gas.

Further, a typical nuclear power plant generates enough energy to power 723,000 homes each year. Comparatively, over 14,000 tons of coal would have to be burned to produce that same amount of energy.

That’s a lot of carbon emissions. Nuclear prevents that unnecessary pollution from coal while generating far more energy.


  1. Reliable energy source

Nuclear power is the most reliable fuel source available. Its capacity factor, the ratio of actual power generated to maximum amount possible, is 91 percent. This is by far the highest of all energy sources.

Nuclear plants are also able to generate energy 24/7 for 18 to 24 months without interruption. This makes nuclear an important source that isn’t subject to fluctuations in price as much as oil or gas. It also means that nuclear can provide energy during times when energy demand and prices are high.

Dinh sees great reliability in the industry as a whole, beyond just the power capabilities of nuclear itself.

“As the operating experience accumulates, the technology becomes more reliable, and advanced designs emerge, the new plants are even more resilient to hazards or human errors,” he said.


Nope! Shut down nuclear ASAP

  1. Effects on the environment

 Nuclear power requires the mining of uranium, a non-renewable radioactive resource. Radioactivity is not to be taken lightly. As we’ve seen with disasters like Fukushima, nuclear radiation can be catastrophic to the environment and human lives.

Monika Kondura is an Environment and Ecology professor at UNC-Chapel Hill. She said that the release of radioactive radiation into the environment remains toxic for thousands of years.

“The radiation released into the environment would be associated with the loss of biodiversity and all the ecological benefits, and most importantly, with major detrimental effects on human health,” she said.

Studies have shown that radiation from the nuclear meltdown at Fukushima has been devastating to surrounding areas. Timothy Mousseau, a professor at the Univeristy of South Carolina, conducted a study on the effects of radiation on birds.

Mousseau and his team found the bird populations they were studying were 30 percent lower than expected. This is double the loss that was observed in a similar study conducted following the aftermath of Chernobyl.

A nuclear meltdown like Fukushima forces us to stop and consider the risks when investing in nuclear technology. While safety precautions have been improved since this accident, future breakdowns are never out of the question.


  1. Disposal of toxic waste

When determining how long a radioactive isotope will linger in the environment, scientists look at half-life. Half-life is the time it takes for the concentration of an isotope to fall to half its original value. The problem with nuclear power is that uranium has a half-life of millions of years.

This long half-life creates a lot of problems when it comes to disposing of toxic waste properly. Currently, radioactive waste from nuclear plants is stored in large cylinders lined with steel and filled with concrete and water. These canisters are kept on-site at nuclear plants.

Dihn said that this type of disposal method meets protection requirements. He’s also hopeful that better techniques will be available in the future.

“Future technology may bring better or stronger and more resilient materials for use as containment,” he said.

Other methods involve burial of waste, which presents other issues. Tunnels have been dug deep beneath earth’s surface to bury waste. Various countries also used ocean floor disposal, until its ban in 1993.

Both methods of burial bring up serious concerns with regard to the environment and possible leeching of waste. And the long half-life of uranium clearly makes the disposal process of nuclear waste even trickier.


  1. Large consumption of fresh water

Consumption of freshwater, or evaporation, can be a big deterrent of nuclear energy.

Nuclear uses once-through and wet-recirculating methods for cooling systems. Once-through cooling takes water from a nearby source, runs it through pipes, and then discharges it back into the source. This is problematic because of thermal pollution’s effect on local ecosystems.

Wet-recirculating is similar to once-through, but involves circulating water through the plant a second time before discharging it. This can consume even more water than once-through because more water is lost as steam. It can also harm ecosystems through thermal pollution.

Most importantly, in comparison to other fuel sources, nuclear consumes the most water. Nuclear even uses more than coal, despite coal’s reputation of consuming enormous amounts of freshwater.

Earth’s population and energy demand are growing exponentially, which makes freshwater resources increasingly valuable. So an energy resource that takes water from human mouths is another factor to consider when planning for the future.


So, what are you trying to say?

Clearly there are valid arguments for each side of nuclear energy, and the world will never agree which is right. What’s important is that nuclear energy hasn’t been ruled out as a source of alternative energy. Therefore, staying informed about future research and development is critical, because nuclear could be an energy game-changer.

FAQs: Renewable Energy Enabling Rural Development

Farmers now have the chance to grow more than just crops.

The growth of the renewable energy industry has led to investment by many in the agriculture industry. But not everyone is convinced such technologies offer substantial advantages.

Below are some of the most common questions surrounding renewable energy and its potential to transform rural communities.

Q: As a person living in a rural community, what is the argument for investing in renewable energy?

A: The ongoing threat of climate change, specifically droughts and floods, increasingly threatens farmer’s harvests. This is where diversification comes in to play.

Diversification is the practice of allocating money for different uses. Farmers can do this by planting multiple crops, instead of relying on the success of a single crop.

It is becoming more important that farmers diversify their income due to the potential for harsh weather in the future. And now farmers have the opportunity to further diversify their incomes by investing in renewables.

Paul Sherman, the associate state legislative director with the North Carolina Farm Bureau Federation, has worked alongside farmers for years. He understands that diversification is a necessity for farmers.

“Diversification spreads out risk throughout the year,” Sherman said.

Instead of being hit hard all at once, diversifying income limits the risk experienced at any one point in time.

One aspect of investing in renewables is farmers are guaranteed a lease payment each year for their land.

Sherman said this provides farmers with money they can count on.

He also said he views the investment in renewable energy as simply an additional utilization of their land.


Q: Isn’t renewable energy expensive?

A: A large criticism of switching to renewable energy is that it’s too expensive. Historically, renewable energy has cost more than its nonrenewable counterparts.

But with the recent rise of solar and wind installations, the costs of these technologies have dropped significantly.

The growth of the solar industry has made the market more competitive, leading to a decline in costs.

Technological innovation has also driven down prices. The International Energy Agency’s 2015 report, Projected Costs of Generating Electricity, detailed a large drop particularly for solar and wind.

The report compares costs of nonrenewable and renewable energy sources. The cost of renewables is difficult to pinpoint due to variation between, and even within, countries. However, findings show onshore wind as the cheapest renewable technology, and solar PV as having a significant decrease in cost.

This IEA report makes it clear that renewable energy sources are no longer considered outliers on the basis of cost.


Q: Are there laws preventing me from putting solar panels/wind turbines on my property?

A: Laws vary by state—and even by county—regarding renewable energy.

It’s important to look up your region and find existing policies that could prevent you from installing renewables.

California, for example, has laws in place that protect homeowner access to the sun for solar panels. The Solar Rights Act states that consumers have the right to access sunlight. It also places restrictions on the ability of homeowner associations and local government to prevent people from installing solar.

However, not all states have such lenient policies. Many require that you go through a homeowner association before installing panels, which can lead to a dead end.


Q: I live in the city. Why should I care about this?

A: Investing in renewable energy by farmers is beneficial to everyone, rural and urban alike.

Despite the distance between residents of urban areas and rural areas, the two are closely connected.

The crops produced in rural communities are the main source of food for urban dwellers. Without the labor of farmers, millions of people would come home to empty tables and refrigerators.

Keeping this in mind, if rural communities struggle to make ends meet, it could impact their harvests the following years. Money is an input of farming, just as fertilizer and machinery are, and a lack of these greatly diminishes yields.

Low yields mean less food supply and higher prices for consumers—in or out of the city.

However, if farmers diversify their income by investing in renewables, it reduces the financial hit brought on by natural disasters. This would then keep food costs stable for people in rural and urban regions alike.


Q: Will utilizing my land for renewable energy take away from the amount of crops I can generate from farming?

A: Joel Olsen, president of O2 Energies, has dedicated much of his work to installing large-scale ground-mounted solar plants on un-utilized farmland.

As someone familiar with farmers’ concerns, he understands why may are hesitant to invest in renewables. He makes sure to always ask the same question before beginning a project: How can we maximize the local impact of what we do?

Olsen knows land is the most precious resource for farmers, so setting aside valuable land for another purpose seems counterintuitive. However, he also works to ensure that the land designated for renewable energy is just as productive. Raising sheep and planting berries in conjunction with solar farms are two practices Olsen has implemented.

Through the integration of agriculture and electricity production, farmers can maintain productive farmland while investing in these technologies. Farmers don’t have to sacrifice land to invest in renewables: energy and crop production can happen simultaneously.

“Clean energy can be the perfect marriage between preserving farmland and generating electricity,” Olsen said.


The Issue of Carbon Tax

The Paris Agreement in December 2015 brought together nearly 200 countries to discuss climate change. For the first time in history, a global agreement to slow climate change was made. Ultimately, world leaders hope to limit the earth’s temperature increase to 1.5 degrees Celsius.

Following the Paris Agreement, however, countries had to ask themselves, “How?”

Carbon tax. The tax leaders hope will spur innovation of renewable energy and slow climate change. It’s also the tax that more and more countries are implementing.

Countries throughout the world are quickly adopting the tax. Provinces in Canada, in particular, are having noticeable results.

In British Columbia, the carbon tax increased gas prices by only 6.67 cents per litre. Surprisingly, since its implementation, gasoline use has drastically declined inBritish Columbia. Additionally, awareness about climate change has increased.

The theory is simple: Put a price on carbon to discourage people from using it. Taxing carbon should decrease greenhouse gas emissions and prevent further warming of the planet. It’s for this reason Sen. Bernie Sanders has long been a proponent of carbon tax.

Sanders has praised the carbon tax for being “straight-forward” and “efficient.” Sanders is known as a “democratic socialist.” Recently, politicians on the right have outwardly supported the carbon tax as well.

Conservative economist Gregory Mankiw believes incentivizing people to reduce their carbon footprint will show results. Nudging people to be efficient will produce the desired outcome of less carbon emissions. Incentives change behavior.

Jerry Taylor, a libertarian thinker, makes the case for supporting carbon tax as well. He believes it’s more effective and efficient than relying on EPA regulation. He thinks it’s the government’s role to step in and protect its citizens.

Conversely, many argue that the carbon tax will only make life harder for everyone.

Some contend that administering the tax could be expensive, and therefore decrease efficiency. This argument is refuted by those who have seen the economic benefit carbon tax.

Laura D’Andrea Tyson, a business professor at the University of California, Berkeley, supports the tax. She believes monetary incentives will create “efficient micro decisions” and “support efficient societal outcomes.” That is, if individuals adjust their behavior, society as a whole will adjust as well.

Additionally, a revenue neutral carbon tax can return money to the taxpayers. The public would be refunded the generated revenue from the tax on a monthly basis. This, in turn, could offset rising energy costs.

It’s possible the U.S. will see legislation on carbon tax within a few years. But it will require support from both sides of the political spectrum. Something almost unheard of.


  1. “How British Columbia Enacted the Most Effective Carbon Tax in North America” 26 Mar. 2014. CityLab. 
  2. “Inside the Paris Climate Deal” 12 Dec. 2015. The New York Times.
  3. “Why We Need a Carbon Tax” 9 July 2014. The Huffington Post.
  4. “This Conservative Economist Makes the Case for a Carbon Tax” 15 Oct. 2015.
  5. “The Conservative Case for a Carbon Tax: Q&A With Jerry Taylor” 5 May 2015. The Huffington Post.
  6. “Carbon Tax — Pros and Cons” 20 Jan. 2013.
  7. “The Risky Business of a Carbon Tax” 17 July 2014.
  8. “The Myriad Benefits of a Carbon Tax” 28 June 2013. The New York Times.
  9. “In charts: how a revenue neutral carbon tax creates jobs, grows the economy” 13 June 2014. The Guardian.
  10. “The Case for a Carbon Tax” 6 June 2015. The New York Times.