Clean energy depends on wider economic growth

Near-Field Thermophotovoltaics captures radiated energy across a nanoscale gap, using thin-film photovoltaic cells and indium gallium arsenide to boost power density and efficiency, enabling compact Army portable power from emitters via radiative heat transfer.

Key Points

A nanoscale TPV method capturing near-field photons for higher power density at lower emitter temperatures.

✅ Nanoscale gap boosts radiative transfer and usable photon flux

✅ Thin-film InGaAs cells recycle sub-band-gap photons via reflector

✅ Achieved ~5 kW/m2 power density with higher efficiency

With the addition of sensors and enhanced communication tools, providing lightweight, portable power has become even more challenging, with concepts such as power from falling snow illustrating how diverse new energy-harvesting approaches are. Army-funded research demonstrated a new approach to turning thermal energy into electricity that could provide compact and efficient power for Soldiers on future battlefields.

Hot objects radiate light in the form of photons into their surroundings. The emitted photons can be captured by a photovoltaic cell and converted to useful electric energy. This approach to energy conversion is called far-field thermophotovoltaics, or FF-TPVs, and has been under development for many years; however, it suffers from low power density and therefore requires high operating temperatures of the emitter.

The research, conducted at the University of Michigan and published in Nature Communications, demonstrates a new approach, where the separation between the emitter and the photovoltaic cell is reduced to the nanoscale, enabling much greater power output than what is possible with FF-TPVs for the same emitter temperature.

This approach, which enables capture of energy that is otherwise trapped in the near-field of the emitter is called near-field thermophotovoltaics or NF-TPV and uses custom-built photovoltaic cells and emitter designs ideal for near-field operating conditions, alongside emerging smart solar inverters that help manage conversion and delivery.

This technique exhibited a power density almost an order of magnitude higher than that for the best-reported near-field-TPV systems, while also operating at six-times higher efficiency, paving the way for future near-field-TPV applications, including remote microgrid deployments in extreme environments, according to Dr. Edgar Meyhofer, professor of mechanical engineering, University of Michigan.

"The Army uses large amounts of power during deployments and battlefield operations and must be carried by the Soldier or a weight constrained system," said Dr. Mike Waits, U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "If successful, in the future near-field-TPVs could serve as more compact and higher efficiency power sources for Soldiers as these devices can function at lower operating temperatures than conventional TPVs."

The efficiency of a TPV device is characterized by how much of the total energy transfer between the emitter and the photovoltaic cell is used to excite the electron-hole pairs in the photovoltaic cell, where insights from near-light-speed conduction research help contextualize performance limits in semiconductors. While increasing the temperature of the emitter increases the number of photons above the band-gap of the cell, the number of sub band-gap photons that can heat up the photovoltaic cell need to be minimized.

"This was achieved by fabricating thin-film TPV cells with ultra-flat surfaces, and with a metal back reflector," said Dr. Stephen Forrest, professor of electrical and computer engineering, University of Michigan. "The photons above the band-gap of the cell are efficiently absorbed in the micron-thick semiconductor, while those below the band-gap are reflected back to the silicon emitter and recycled."

The team grew thin-film indium gallium arsenide photovoltaic cells on thick semiconductor substrates, and then peeled off the very thin semiconductor active region of the cell and transferred it to a silicon substrate, informing potential interfaces with home battery systems for distributed use.

All these innovations in device design and experimental approach resulted in a novel near-field TPV system that could complement distributed resources in virtual power plants for resilient operations.

"The team has achieved a record ~5 kW/m2 power output, which is an order of magnitude larger than systems previously reported in the literature," said Dr. Pramod Reddy, professor of mechanical engineering, University of Michigan.

Researchers also performed state-of-the-art theoretical calculations to estimate the performance of the photovoltaic cell at each temperature and gap size, informing hybrid designs with backup fuel cell solutions that extend battery life, and showed good agreement between the experiments and computational predictions.

"This current demonstration meets theoretical predictions of radiative heat transfer at the nanoscale, and directly shows the potential for developing future near-field TPV devices for Army applications in power and energy, communication and sensors," said Dr. Pani Varanasi, program manager, DEVCOM ARL that funded this work.

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Berkshire Hathaway Energy Wind Power drives cheap electricity rates in Iowa via utility-scale wind turbines, integrated transmission, battery storage, and grid management, delivering renewable energy, stable pricing, and long-term rate freezes through 2028.

Key Points

A vertically integrated wind utility lowering Iowa rates via owned generation, transmission, and advanced grid control.

✅ Owned wind assets meet Iowa residential demand

✅ Integrated transmission lowers costs and losses

✅ Rate freeze through 2028 sustains cheap power

In his latest letter to Berkshire Hathaway shareholders, Warren Buffett used the 20th anniversary of Berkshire Hathaway Energy to tout its cheap electricity bills for customers.

When Berkshire purchased the majority share of BHE in 2000, the cost of electricity for its residential customers in Iowa was 8.8 cents per kilowatt-hour (kWh) on average. Since then, these electricity rates have risen at a paltry <1% per year, with a freeze on rate hikes through 2028. As anyone who pays an electricity bill knows, that is an incredible deal.  

As Buffett himself notes with alacrity, “Last year, the rates [BHE’s competitor in Iowa] charged its residential customers were 61% higher than BHE’s. Recently, that utility received a rate increase that will widen the gap to 70%.”

The Winning Strategy

So, what’s Buffett’s secret to cheap electricity? Wind power.

“The extraordinary differential between our rates and theirs is largely the result of our huge accomplishments in converting wind into electricity,” Buffett explains. 

Wind turbines in Iowa that BHE owns and operates are expected to generate about 25.2 million megawatt-hours (MWh) of electricity for its customers, as projects like Building Energy operations begin to contribute. By Buffett’s estimations, that will be enough to power all of its residential customers’ electricity needs in Iowa.  

The company has plans to increase its renewable energy generation in other regions as well. This year, BHE Canada is expected to start construction on a 117.6MW wind farm in Alberta, Canada with its partner, Renewable Energy Systems, that will provide electricity to 79,000 homes in Canada’s oil country.

Observers note that Alberta is a powerhouse for both green energy and fossil fuels, underscoring the region's unique transition.

But I would argue that the secret to BHE’s success perhaps goes deeper than transitioning to sources of renewable energy. There are plenty of other utility companies that have adopted wind and solar power as an energy source. In the U.S., where renewable electricity surpassed coal in 2022, at least 50% of electricity customers have the option to buy renewable electricity from their power supplier, according to the Department of Energy. And some states, such as New York, have gone so far as to allow customers to pick from providers who generate their electricity.

What differentiates BHE from a lot of the competition in the utility space is that it owns the means to generate, store, transmit and supply renewable power to its customers across the U.S., U.K. and Canada, with lessons from the U.K. about wind power informing policy.

In its financial filings for 2019, the company reported that it owns 33,600MW of generation capacity and has 33,400 miles of transmission lines, as well as a 50% interest in Electric Transmission Texas (ETT) that has approximately 1,200 miles of transmission lines. This scale and integration enables BHE to be efficient in the distribution and sale of electricity, including selling renewable energy across regions.

BHE is certainly not alone in building renewable-energy fueled electricity dominions. Its largest competitor, NextEra, built 15GW of wind capacity and has started to expand its utility-scale solar installations. Duke Energy owns and operates 2,900 MW of renewable energy, including wind and solar. Exelon operates 40 wind turbine sites across the U.S. that generate 1,500 MW.

Integrated Utilities Power Ahead

It’s easy to see why utility companies see wind as a competitive source of electricity compared to fossil fuels. As I explained in my previous post, Trump’s Wrong About Wind, the cost of building and generating wind energy have fallen significantly over the past decade. Meanwhile, improvements in battery storage and power management through new technological advancements have made it more reliable (Warren Buffett bet on that one too).

But what is also striking is that integrated power and transmission enables these utility companies to make those decisions; both in terms of sourcing power from renewable energy, as well as the pricing of the final product. Until wind and solar power are widespread, these utility companies are going to have an edge of the more fragmented ends of the industry who can’t make these purchasing or pricing decisions independently. 

Warren Buffett very rarely misses a beat. He’s not the Oracle of Omaha for nothing. Berkshire Hathaway’s ownership of BHE has been immensely profitable for its shareholders. In the year ended December 31, 2019, BHE and its subsidiaries reported net income attributable to BHE shareholders of $2.95 billion.

There’s no question that renewable energy will transform the utility industry over the next decade. That change will be led by the likes of BHE, who have the power to invest, control and manage their own energy generation assets.

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Thermoelectric Materials convert waste heat into electricity via the Seebeck effect; quantum computations and semiconductors accelerate discovery, enabling clean energy, higher efficiency, and scalable heat-to-power conversion from abundant, non-toxic, cost-effective compounds.

Key Points

Thermoelectric materials turn waste heat into electricity via the Seebeck effect, improving energy efficiency.

✅ Convert waste heat to electricity via the Seebeck effect

✅ Quantum computations rapidly identify high-performance candidates

✅ Target efficient, low-thermal-conductivity, non-toxic, abundant compounds

The need to transition to clean energy is apparent, urgent and inescapable. We must limit Earth’s rising temperature to within 1.5 C to avoid the worst effects of climate change — an especially daunting challenge in the face of the steadily increasing global demand for energy and the need for reliable clean power, with concepts that can generate electricity at night now being explored worldwide.

Part of the answer is using energy more efficiently. More than 72 per cent of all energy produced worldwide is lost in the form of heat, and advances in turning thermal energy into electricity could recover some of it. For example, the engine in a car uses only about 30 per cent of the gasoline it burns to move the car. The remainder is dissipated as heat.

Recovering even a tiny fraction of that lost energy would have a tremendous impact on climate change. Thermoelectric materials, which convert wasted heat into useful electricity, can help, especially as researchers pursue low-cost heat-to-electricity materials for scalable deployment.

Until recently, the identification of these materials had been slow. My colleagues and I have used quantum computations — a computer-based modelling approach to predict materials’ properties — to speed up that process and identify more than 500 thermoelectric materials that could convert excess heat to electricity, and help improve energy efficiency.

Making great strides towards broad applications
The transformation of heat into electrical energy by thermoelectric materials is based on the “Seebeck effect.” In 1826, German physicist Thomas Johann Seebeck observed that exposing the ends of joined pieces of dissimilar metals to different temperatures generated a magnetic field, which was later recognized to be caused by an electric current.

Shortly after his discovery, metallic thermoelectric generators were fabricated to convert heat from gas burners into an electric current. But, as it turned out, metals exhibit only a low Seebeck effect — they are not very efficient at converting heat into electricity.

In 1929, the Russian scientist Abraham Ioffe revolutionized the field of thermoelectricity. He observed that semiconductors — materials whose ability to conduct electricity falls between that of metals (like copper) and insulators (like glass) — exhibit a significantly higher Seebeck effect than metals, boosting thermoelectric efficiency 40-fold, from 0.1 per cent to four per cent.

This discovery led to the development of the first widely used thermoelectric generator, the Russian lamp — a kerosene lamp that heated a thermoelectric material to power a radio.

Are we there yet?
Today, thermoelectric applications range from energy generation in space probes to cooling devices in portable refrigerators, and include emerging thin-film waste-heat harvesters for electronics as well. For example, space explorations are powered by radioisotope thermoelectric generators, converting the heat from naturally decaying plutonium into electricity. In the movie The Martian, for example, a box of plutonium saved the life of the character played by Matt Damon, by keeping him warm on Mars.

In the 2015 film, The Martian, astronaut Mark Watney (Matt Damon) digs up a buried thermoelectric generator to use the power source as a heater.

Despite this vast diversity of applications, wide-scale commercialization of thermoelectric materials is still limited by their low efficiency.

What’s holding them back? Two key factors must be considered: the conductive properties of the materials, and their ability to maintain a temperature difference, as seen in nighttime electricity from cold concepts, which makes it possible to generate electricity.

The best thermoelectric material would have the electronic properties of semiconductors and the poor heat conduction of glass. But this unique combination of properties is not found in naturally occurring materials. We have to engineer them, drawing on advances such as carbon nanotube energy harvesters to guide design choices.

Searching for a needle in a haystack
In the past decade, new strategies to engineer thermoelectric materials have emerged due to an enhanced understanding of their underlying physics. In a recent study in Nature Materials, researchers from Seoul National University, Aachen University and Northwestern University reported they had engineered a material called tin selenide with the highest thermoelectric performance to date, nearly twice that of 20 years ago. But it took them nearly a decade to optimize it.

To speed up the discovery process, my colleagues and I have used quantum calculations to search for new thermoelectric candidates with high efficiencies. We searched a database containing thousands of materials to look for those that would have high electronic qualities and low levels of heat conduction, based on their chemical and physical properties. These insights helped us find the best materials to synthesize and test, and calculate their thermoelectric efficiency.

We are almost at the point where thermoelectric materials can be widely applied, but first we need to develop much more efficient materials. With so many possibilities and variables, finding the way forward is like searching for a tiny needle in an enormous haystack.

Just as a metal detector can zero in on a needle in a haystack, quantum computations can accelerate the discovery of efficient thermoelectric materials. Such calculations can accurately predict electron and heat conduction (including the Seebeck effect) for thousands of materials and unveil the previously hidden and highly complex interactions between those properties, which can influence a material’s efficiency.

Large-scale applications will require themoelectric materials that are inexpensive, non-toxic and abundant. Lead and tellurium are found in today’s thermoelectric materials, but their cost and negative environmental impact make them good targets for replacement.

Quantum calculations can be applied in a way to search for specific sets of materials using parameters such as scarcity, cost and efficiency, and insights can even inform exploratory devices that generate electricity out of thin air in parallel fields. Although those calculations can reveal optimum thermoelectric materials, synthesizing the materials with the desired properties remains a challenge.

A multi-institutional effort involving government-run laboratories and universities in the United States, Canada and Europe has revealed more than 500 previously unexplored materials with high predicted thermoelectric efficiency. My colleagues and I are currently investigating the thermoelectric performance of those materials in experiments, and have already discovered new sources of high thermoelectric efficiency.

Those initial results strongly suggest that further quantum computations can pinpoint the most efficient combinations of materials to make clean energy from wasted heat and the avert the catastrophe that looms over our planet.

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Texas EV Registration Fee adds a $200 annual charge under Senate Bill 505, offsetting lost gasoline tax revenue to the State Highway Fund, impacting electric vehicle owners at registration and renewals across Texas.

Key Points

A $200 yearly charge on electric vehicles to replace lost gasoline tax revenue and support Texas Highway Fund road work.

✅ $200 due at registration or renewal; $400 upfront on new EVs.

✅ Enacted by Senate Bill 505 to offset lost gasoline tax revenue.

✅ Advocates propose mileage-based fees; limited $2,500 rebates exist.

Plano resident Tony Federico bought his Tesla five years ago in part because he hated spending lots of money on gas, and Supercharger billing changes have also influenced charging expenses. But that financial calculus will change slightly on Sept. 1, when Texas will start charging electric vehicle drivers an additional fee of $200 each year.

“It just seems like it’s arbitrary, with no real logic behind it,” said Federico, 51, who works in information technology. “But I’m going to have to pay it.”

Earlier this year, state lawmakers passed Senate Bill 505, which requires electric vehicle owners to pay the fee when they register a vehicle or renew their registration, even as fights for control over charging continue among utilities, automakers and retailers. It’s being imposed because lawmakers said EV drivers weren’t paying their fair share into a fund that helps cover road construction and repairs across Texas.

The cost will be especially high for those who purchase a new electric vehicle and have to pay two years of registration, or $400, up front.

Texas agencies estimated in a 2020 report that the state lost an average of $200 per year in federal and state gasoline tax dollars when an electric vehicle replaced a gas-fueled one. The agencies called the fee “the most straightforward” remedy.

Gasoline taxes go to the State Highway Fund, which the Texas Department of Transportation calls its “primary funding source.” Electric vehicle drivers don’t pay those taxes, though, because they don’t use gasoline.

Still, EV drivers do use the roads. And while electric vehicles make up a tiny portion of cars in Texas for now, that fraction is expected to increase, raising concerns about state power grids in the years ahead.

Many environmental and consumer advocates agreed with lawmakers that EV drivers should pay into the highway fund but argued over how much, and debates over fairer vehicle taxes are surfacing abroad as well.

Some thought the state should set the fee lower to cover only the lost state tax dollars, rather than both the state and federal money, because federal officials may devise their own scheme. Others argued the state should charge nothing because EVs help reduce greenhouse gas emissions that drive climate change and can offer budget benefits for many owners.

“We urgently need to get more electric vehicles on the road,” said Luke Metzger, executive director of Environment Texas. “Any increased fee could create an additional barrier for Texans, and particularly more moderate- to low-income Texans, to make that transition.”

Tom “Smitty” Smith, the executive director of the Texas Electric Transportation Resources Alliance, advocated for a fee based on how many miles a person drove their electric car, which would better mirror how the gas taxes are assessed.

Texas has a limited incentive that could offset the cost: It offers rebates of up to $2,500 for up to 2,000 new hydrogen fuel cell, electric or hybrid vehicles every two years. Adrian Shelley, Public Citizen’s Texas office director, recommended that the state expand the rebates, noting that state-level EV benefits can be significant.

In the Houston area, dealer Steven Wolf isn’t worried about the fee deterring potential customers from buying the electric Ford F-150 Lightning and Mustang Mach-E vehicles he sells. Electric cars are already more expensive than comparable gasoline-fueled cars, and charging networks compete for drivers, he said.

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UK Nuclear Power Expansion is vital for low-carbon baseload, energy security, and Net Zero, complementing renewables like wind and solar, reducing gas reliance, and unlocking investment through clear financing rules and proven, dependable reactor technology.

Key Points

Accelerating reactor build-out for low-carbon baseload to boost energy security and help deliver the UK Net Zero target.

✅ Cuts gas dependence and stabilizes grids with firm capacity.

✅ Complements wind and solar for reliable, low-carbon supply.

✅ Needs clear financing to unlock investment and lower costs.

Leading nuclear industry figures will today call for a major programme of new power stations to hit ambitious emissions reduction targets.

The 19th Nuclear Industry Association annual conference in London will highlight the need for a proven, dependable source of low carbon electricity generation alongside growth in weather-dependent solar and wind power, and particularly the rapid expansion of wind and solar generation across the UK.

Without this, they argue, the country risks embedding a major reliance on carbon-emitting gas fired power stations as Europe loses nuclear capacity at a critical time for energy security for generations to come.

Annual public opinion polling released today to coincide with the conference revealed 75% of the population want the UK Government to take more action to reduce CO2 emissions.

The survey, conducted by YouGov in October 2019, has tracked opinion trends on nuclear for more than a decade. It shows continued and consistent public support for an energy mix including nuclear and renewables, with 72% of respondents agreeing this was needed to ensure a reliable supply of electricity.

Nuclear power was also perceived as the most secure energy source for keeping the lights on, compared to other sources such as oil, gas, coal, wind power, fracking and solar power.

Last month both the Labour and Conservative Parties committed to new nuclear power as part of their election Manifestos and the government's wider green industrial revolution plans for clean growth. At the same time, 27 leading figures in the fields of environment, energy, and industry signed an open letter addressed to parliamentary candidates, which set out the benefits of nuclear and underscored the consequences of not, at least, replacing the UK's current fleet of power stations.

The Nuclear Industry Association said there is no time to be lost in clarifying the ambition and the financing rules for new nuclear power which would bring down costs and unlock a major programme of investment.

Tom Greatrex, Chief Executive of the NIA, said "We have to grow the industry's contribution to a low carbon economy. The independent Committee on Climate Change said earlier this year that we need a variety of technologies including nuclear power/1 for net zero to reach the UK's Net Zero emissions target by 2050".

"This is a proven, dependable, technology with lower lifecycle CO2 emissions than solar power and the same as offshore wind/2. It is also an important economic engine for the UK, supporting uses beyond electricity and creating high quality direct and indirect employment for around 155,000 people."

"Right now nuclear provides 20%/3 of all the UK's electricity but all but one of our existing fleet will close over the next decade, amid the debate over nuclear's decline as power demand will only increase with a shift to electric heating and vehicles."

"The countries and regions which have most successfully decarbonised, like Sweden, France and Ontario in Canada, have done so by relying on nuclear, aligning with Canada's climate goals for affordable, safe power today. You are not serious about tackling climate change if you are not serious about nuclear".

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Bitcoin energy consumption is driven by mining electricity demand, with TWh-scale power use, carbon footprint concerns, and Cambridge estimates. Rising prices incentivize more hardware; efficiency gains and renewables adoption shape sustainability outcomes.

Key Points

Bitcoin energy consumption is mining's electricity use, driven by price, device efficiency, and energy mix.

✅ Cambridge tool estimates ~121 TWh annual usage

✅ Rising BTC price incentivizes more mining hardware

✅ Efficiency, renewables, and costs shape footprint

"Mining" for the cryptocurrency is power-hungry, with power curtailments reported during heat waves, involving heavy computer calculations to verify transactions.

Cambridge researchers say it consumes around 121.36 terawatt-hours (TWh) a year - and is unlikely to fall unless the value of the currency slumps, even as Americans use less electricity overall.

Critics say electric-car firm Tesla's decision to invest heavily in Bitcoin undermines its environmental image.

The currency's value hit a record $48,000 (£34,820) this week. following Tesla's announcement that it had bought about $1.5bn bitcoin and planned to accept it as payment in future.

But the rising price offers even more incentive to Bitcoin miners to run more and more machines.

And as the price increases, so does the energy consumption, according to Michel Rauchs, researcher at The Cambridge Centre for Alternative Finance, who co-created the online tool that generates these estimates.

“It is really by design that Bitcoin consumes that much electricity,” Mr Rauchs told BBC’s Tech Tent podcast. “This is not something that will change in the future unless the Bitcoin price is going to significantly go down."

The online tool has ranked Bitcoin’s electricity consumption above Argentina (121 TWh), the Netherlands (108.8 TWh) and the United Arab Emirates (113.20 TWh) - and it is gradually creeping up on Norway (122.20 TWh).

The energy it uses could power all kettles used in the UK, where low-carbon generation stalled in 2019, for 27 years, it said.

However, it also suggests the amount of electricity consumed every year by always-on but inactive home devices in the US alone could power the entire Bitcoin network for a year, and in Canada, B.C. power imports have helped meet demand.

Mining Bitcoin
In order to "mine" Bitcoin, computers - often specialised ones - are connected to the cryptocurrency network.

They have the job of verifying transactions made by people who send or receive Bitcoin.

This process involves solving puzzles, which, while not integral to verifying movements of the currency, provide a hurdle to ensure no-one fraudulently edits the global record of all transactions.

As a reward, miners occasionally receive small amounts of Bitcoin in what is often likened to a lottery.

To increase profits, people often connect large numbers of miners to the network - even entire warehouses full of them, as seen with a Medicine Hat bitcoin operation backed by an electricity deal.

That uses lots of electricity because the computers are more or less constantly working to complete the puzzles, prompting some utilities to consider pauses on new crypto loads in certain regions.

The University of Cambridge tool models the economic lifetime of the world's Bitcoin miners and assumes that all the Bitcoin mining machines worldwide are working with various efficiencies.

Using an average electricity price per kilowatt hour ($0.05) and the energy demands of the Bitcoin network, it is then possible to estimate how much electricity is being consumed at any one time, though in places like China's power sector data can be opaque.
 

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