Green Tech

ElectraTherm, which has developed a relatively small machine for making electricity from waste heat, has raised $2.6 million and plans a follow-on round next year.

The Carson City, Nev.-based company's ElectraTherm Green Machine is designed to squeeze power from the heat thrown off at industrial facilities like factories, saw mills, or oil and gas operations.

A 50-kilowatt generator that runs on industrial waste heat.

(Credit: ElectraTherm)

The company intends to make units that range in size from 30 kilowatts to 500 kilowatts, enough to offset electricity use at an industrial facility. A 50 kilowatt unit can generate roughly what 40 U.S. homes consume.

The money from the $2.6 million Series A was from Michigan investor Interlaken and angel investors, said William Olsen, ElectraTherm's vice president of business development. He said the company intends to raise more money--in the range of $5 million to $8 million--early next year to expand manufacturing.

The company has made only a handful of units so far, including one installed at Southern Methodist University. But Olsen said the company is in discussions with utilities, oil and gas companies, and other industrial firms looking for energy-efficiency technologies.

"There's waste heat everywhere," he said. "We've been able to convince (potential customers) that the technology works. At this stage, it's just helping them deploy it."

The generator uses an organic Rankine cycle to convert heat into electrical energy. It channels heat to a refrigerant that is converted to a gas by the heat. The vapor pressure caused from that reaction turns a mechanism that is connected to a generator that makes electricity.

ElectraTherma certainly isn't the only company that has equipment to turn industrial waste heat into electricity. But its product design allows it to operate at relatively small scale and low temperatures, as low as 200 degrees, Olsen said.

When fossil fuels are burned, about two thirds of the energy content is wasted. The net effect of a heat-capturing machine is to squeeze another ten percent of energy from those fuels, Olsen said.

The cost for a 50-kilowatt system is $128,000. Depending on the cost of electricity, the payback is typically under three years, according to the company.

How's this for a tantalizing possibility: rather than install solar panels on your roof, the lost heat from your furnace could power your home.

That's not yet a product, but a growing number of scientists and clean-tech companies are trying to coax usable energy from smokestacks and other waste-heat sources.

A global push toward energy efficiency is prodding more industrial outfits to reuse heat from their operations that would otherwise be lost to the skies.

Meanwhile, improving thermoelectric technology that converts heat into electricity is being fitted onto everything from car exhaust pipes to furnace flues.

It's a sign that energy efficiency, which often takes a backseat to renewable energy or alternative fuels, is getting more attention from technology innovators.

One company, GMZ Energy which was formed earlier this year by researchers from Boston College and the Massachusetts Institute of Technology, is taking a high-tech path to waste-heat recovery.

It has developed a nanomaterial-manufacturing process that improves the efficiency of existing thermoelectric modules, which are usually made from bismuth telluride and look something like a computer chip.

Thermoelectric devices can work in two directions: passing an electrical current through a module creates heat on one side and cooling on the other. Working in the reverse, applying heat to a device will create electricity.

Initially, GMZ Energy plans to sell modules to the existing market for cooling in small refrigerators or server racks, CEO Mike Clary said. The bigger market--on the order of billions of dollars--is converting waste heat from smokestacks or industrial equipment to electricity, he said.

"Eventually, we're going to see a tremendous amount of waste heat recovery applications, but that's 5 to 10 years off," Clary said. "We have to get to that 10 percent efficiency threshold to start making it viable."

Clary said appliance maker Bosch has shown interest in making a home-heating unit with an attachment that makes electricity from exhaust heat. At 10 percent efficiency, a home could meet its power needs with the heat on.

GMZ's prototype modules now operate at about 7 percent efficiency, 30 percent or 40 percent better for cooling than existing devices, Clary said.

A thermoelectric module, which one company intends to use for harvesting waste heat to make electricity.

(Credit: Martin LaMonica/CNET News)

The company, which got its seed funding from venture capital firm Kleiner Perkins Caufield & Byers, is looking to raise a round of funding in September to set up assembly operations in China, Clary said.

It is also readying a technical paper to show that its manufacturing process, where material is milled and then repressed into an ingot, works with both bismuth antimony telluride and silicon germanium for high-temperature applications.

Make steam, make juice
Automakers, too, are investigating heat recovery through thermoelectric devices.

BMW and General Motors are reviving work in this area and plan to test attachments to exhaust pipes next year. So far, research indicates that mileage could be improved by about 5 percent, or 1 mile per gallon, on a Chevrolet Suburban.

GMZ Energy's Clary thinks that automakers' interest in thermoelectrics is one reason the market is likely to take shape. He also notes that many researchers are working in the area.

But even before any breakthroughs in advanced materials, many people consider waste heat recovery the proverbial low-hanging fruit in energy efficiency.

"The market is a lot of wasted energy, and that is, by definition, a zero-cost feedstock," said Roger Ballentine, president of Green Strategies and a clean-tech investor. "That's a pretty attractive proposition."

A traditional heat recovery system. Click to see larger image.

(Credit: Recycled Energy Development)

Ballentine has consulted for China Energy Recovery, a Shanghai-based company that says it can capture 90 percent of energy that would otherwise be lost.

Efficiency, in general, is less sexy than renewable-power generation, an area that attracts more entrepreneurs and investors. But the economics of efficiency are usually better, said Ballentine, who expects to see more growth in heat recovery.

"If energy prices keep going up, the economics keep getting better," he said.

Co-generation plants, where both heat and electricity are produced, have been around for many years. Yet even though it is a cleaner form of power generation than burning fossil fuels, combined heat and power has held steady, at 9 percent of energy production, for several years, according to the World Alliance for Decentralized Energy.

Wasting away
The granddaddy of the waste heat recovery business is Recycled Energy Development, whose chairman, Thomas Casten, has been involved in energy-recycling projects for 30 years.

In projects at power plants or factories, the company places coils around a smokestack or other equipment to heat water. That hot water is then pumped back into the facility for heating or industrial processes. Or the hot water is turned into pressurized steam to make electricity in a turbine.

The amount of heat in a typical power plant that goes up in smoke is a "problem and an embarrassment," said Dick Munson, senior vice president at Recycled Energy Development, who spoke at the Virtual Energy Forum in June.

The average U.S. power plant uses three units of fuel to do one unit of power, meaning that two-thirds of the energy content is vented as waste, he said.

The efficiency of power plants in the United States has not improved in 50 years, while industry in Denmark has managed to increase efficiency 60 percent in the last three years, he said.

One customer is taking wasted energy from a steel smelter to make 220 megawatts of electricity. That's on the order of a single large solar-power plant. Through waste heat recovery, the U.S. could generate the equivalent of 400 coal-fired power plants, Munson said.

Polices need to be updated to better favor efficiency, Munson argued. Another barrier to industrial-scale heat-recycling projects is high capital costs, Ballentine added.

But one of the biggest impediments to heat recovery is changing the mind-set of building operators and product designers.

That's even truer of thermoelectric technology, which still needs to improve before more people look at it seriously, said GMZ Energy's Clary. A hybrid car or diesel truck, for example, could improve efficiency, as could a solar-thermal power generator.

"New ways of thinking like that just don't happen overnight in complex systems that have complex product cycles," he said. "As people get dialed into it, and the performance goes up, it will take off."

Pavement, it turns out, is a pretty good place to look for free energy.

A handful of Massachusetts researchers on Monday published a paper detailing a technique for using water-carrying pipes to convert the built-up heat in asphalt roads into usable energy.

Researchers measure ways to transfer heat from a source, such as this lamp shining over asphalt, to water.

(Credit: Worcester Polytechnic Institute)

Released at the International Symposium on Asphalt Pavements and Environment in Zurich, Switzerland, the paper argues that asphalt roads have a number of advantages over solar-electric panels as a source of distributed energy.

"The significance of this concept lies in the fact that the massive installed base of parking lots and roadways creates a low-cost solar collector an order of magnitude more productive than traditional solar cells. The significantly high surface area can offset the expected lower efficiency (compared to traditional solar cells) by several orders of magnitude, and hence result in significantly lower cost per unit of power produced," according to the paper.

Blacktops can continue to generate energy after the sun goes down, and upgrades with heat exchangers could be fit into road constructions, which are done every 10 to 12 years, Rajib Mallick, associate professor of civil and environmental engineering at Worcester Polytechnic Institute, said in a statement.

Also, wicking heat away from roads could reduce the "heat island" effect in densely populated areas where temperatures rise when buildings and pavement release heat accumulated during the day.

The researchers used computer modeling and small-scale prototypes to test alternatives to pipes for transferring asphalt heat to water.

It found that the depth of the heat exchanger was critical and that a material with higher heat conductivity, such as quartzite, can be added to asphalt to improve heat transfer.

The hot water from the roads could be used in neighboring buildings, something that has already been done in the Netherlands. A more sophisticated approach would be to convert the heat into electricity using thermoelectric modules.

"Our preliminary results provide a promising proof of concept for what could be a very important future source of renewable, pollution-free energy for our nation. And it has been there all along, right under our feet," Mallick said.

Thermoelectricity--the practice of drawing electricity from heat--is getting a real-life work-out.

ElectraTherm on Thursday said that it has installed a 50-kilowatt machine that uses industrial waste heat as its "fuel."

A 50 kilowatt 'green machine' that runs on waste heat.

(Credit: ElectraTherm)

The company says that the ElectraTherm Green Machine, installed at Southern Methodist University in Dallas, will recoup its purchase cost in three to four years with electricity costing three or four cents per kilowatt-hour during that time.

The machine uses an organic Rankine cycle to heat liquids which are turned into a vapor that turns a turbine to make electricity.

The thermoelectric effect has been known since the early 19th century. But the idea of making electricity from heat appears to be getting more attention.

Kleiner Perkins Caufield & Byers earlier this year funded an spin-off from the Massachusetts Institute of Technolocy called GMZ Energy.

ElectraTherm says that its unit doesn't require any specialized electronics and is relatively easy to maintain. The basic technology can be scaled up to produce up to 500 kilowatts.

For comparison, a typical home solar installation can generate between two and four kilowatts, while Google's solar array at its corporate headquarters--considered the largest in the U.S.--is 1.6 megawatts.

Preston Koerner in the Jetson Green green-building blog said the ElectraTherm machine demonstrates that heat-to-electricity can be done at a relatively small scale. It generates about enough electricity for about 40 homes, he added.

China is the Saudi Arabia of waste heat, according to Roger Ballentine, president of Green Strategies.

The country's power plants aren't very efficient and, unlike Denmark or Japan, China hasn't invested a lot in technologies that can capture the heat and harness it to produce electricity. That means there's a vast amount of potential energy being squandered--or waiting to be tapped by an entrepreneur or two.

China isn't alone. Over half of the electricity produced in the U.S., for instance, never actually gets used for a productive purpose. A lot of it gets converted into heat, and is then lost.

"There is a tremendous amount of low-hanging fruit," Ballentine said. "Power plants in the U.S. make more heat than Japan uses in a year."

As a result, expect to see a number of companies pursuing this opportunity. China Energy Recovery, for instance, announced this week that it has landed $8.5 million in financing to expand operations. (Ballentine consults for CER.).

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In the U.S., meanwhile, keep an eye on Recycled Energy Development, founded by Tom Casten, one of the big names in the industry. He also founded Trigen Energy and Primary Energy.

And GMZ Energy, spun out of Boston College and MIT, says that it too has a more efficient way for converting heat to electricity.

Recycled Energy, like most companies in this business, doesn't sell equipment. Rather, the companies install it at a power plant, maintain it, and get paid according to the percentage of power the equipment saves. If power consumption, controlling for variables, drops by $1 million, a company might receive $500,000, for example.

The technology, Ballentine said, is fairly well-established. Mostly, getting energy out of waste heat revolves around getting companies to adopt it.

The batteries in hybrid cars now get recharged slightly whenever the driver taps the brakes. If research at Honda pans out, heat from the engines could do the same thing.

The Japanese auto giant has released a paper detailing how a Rankine cycle co-generation unit could help recharge the battery in a hybrid and thereby increase gas mileage, according to Green Car Congress. Honda put the Rankine unit in a test car (a Honda Stream) and found that the unit generated more electricity than regenerative braking. However, the unit isn't very efficient so more work will be required before Honda can put one of these in cars.

Waste heat, according to some, is one of the untapped sources of power in the world. Some have proposed harnessing the waste heat from nuclear plants to run water purification systems or produce hydrogen.

The tough part is that it's not easy. Paul Marcoux, vice president of green engineering at Cisco Systems, was recently asked if computer companies could harvest heat from processors and hard drives and turn that into power. Probably not, he said. The temperature generally doesn't get hot enough.

In a Rankine unit, a water pump keeps water under high pressure. Heat from the gas engine in a hybrid is then captured, compressed, and used to make steam out of the water. The steam then turns a generator to make electricity, which charges the battery that runs the electric motor.

Hybrids have two motors: one gas, one electric. In conventional hybrids, the electric motor powers the car around town while the gas motor does more of the work on the freeway. General Motors and Tesla Motors are building cars in which the gas motor doesn't drive the car at all, but runs a generator which charges the battery for the electric motor. Conceivably, a Rankine system could be used in either but would probably work better in a conventional hybrid because the gas engine is larger.

Right now, Honda's Rankine unit is only about 13 percent efficient.

Honda is also trying to bring efficient, cleaner, high-mileage diesels to the United States.