A single bottle of dirty water transformed into the power source for a home—such was the promise of a technology package that became known as the “artificial leaf.” And such was the vision introduced by its inventor, Daniel Nocera, at the inaugural summit of the Advanced Research Projects Agency–Energy in 2010.
 
The artificial leaf pledged to store 30 kilowatt-hours of electricity after a mere four hours of splitting water into oxygen and hydrogen, or enough to power an average American “McMansion” for a day. It was exactly the kind of "high-risk, high-reward" technology touted by President Obama when he launched the agency in 2009 (an idea carried over from the George W. Bush–era). Such technologies could help with the country's energy, environmental and economic security by creating new industries and jobs as well as by reducing the pollution associated with energy production and use today. More succinctly, "ARPA–E turns things that are plausible into things that are possible," proclaimed Acting Director Cheryl Martin at the 2014 summit.
 
Out of 37 projects that received initial ARPA–E funding, Sun Catalytix, a company founded by Nocera, was the poster child—or rather video favorite—featured in a U.S. Department of Energy (DoE) clip talking up the potential of transformational change. "Almost all the solar energy is stored in water-splitting," intoned Nocera, a Massachusetts Institute of Technology chemist, at the inaugural ARPA–E summit. "Shift happens."
 
The artificial leaf proved to be possible but implausible, however. It won't be splitting water using sunlight on a mass scale anytime soon, its hydrogen dreams blown away by a gale of cheap natural gas that can also be easily converted to the lightest element. So Sun Catalytix has set the artificial leaf aside and shifted focus to flow batteries, rechargeable fuel cells that use liquid chemistry to store electricity. A better flow battery might not shift the fundamental fuel of the American dream but it could help utilities cope with the vagaries of wind and solar power—and is more likely to become a salable product in the near future.
 
Five years in, ARPA–E's priorities have shifted, too, for the same reason. The cheap natural gas freed from shale by horizontal drilling and hydraulic fracturing (or fracking) has helped kill off bleeding-edge programs like Electrofuels, a bid to use microbes to turn cheap electricity into liquid fuels, and ushered in programs like REMOTE, a bid to use microbes to turn cheap natural gas into liquid fuels. Even at the first summit in 2010, so full of alternative energy promise, this gassy revolution was becoming apparent. Consulting firm Black & Veatch predicted that burning natural gas would provide nearly half of all U.S. electricity by 2034, a forecast fulfilled a few decades early in 2012. "We've got a lot of cheap gas," said ARPA–E Program Director Dane Boysen at the 2014 summit. "The question is: What should we do with it?"
 
Boysen's Methane Opportunities for Vehicular Energy, or MOVE program focuses on building a better tank for that gas. And ARPA–E's focus seems to have shifted from innovations that might upend the existing energy system—a hydrogen economy or fuels knit out of electricity—to ones that might end up in existing technology—cars that run on natural gas or better batteries. Is enabling the energy predominance of another fossil fuel the kind of transformation ARPA–E is supposed to expedite? And if it isn't, does that mean ARPA–E is failing?
 
The measure of success
ARPA–E points to follow-on funding from other entities (whether corporate, government or venture capital) as an early measure of its success. So far, the agency has invested more than $900 million in 362 different research projects. Of those projects, 22 have garnered an additional $625 million from capitalists of one type or another; it is a group that includes Sun Catalytix. ARPA–E funding has also allowed 24 projects to form spin-off companies whereas 16 projects have found a new funding source from other government agencies, including the DoE, which runs ARPA–E, and the Department of Defense.
 
The biggest successes include Makani Power, which makes souped up kites for wind power, and was acquired by Google after ARPA–E invested $6 million developing the technology. There’s also Ambri, which makes liquid-metal batteries for cheap energy storage on a massive scale and is now developing units capable of storing 20 kilowatt-hours for testing later this year. And there’s 1366 Technologies, which became the first (and only, at that time in 2009) ARPA–E grantee in photovoltaics with a new manufacturing method that wastes less silicon. The company will begin construction this year on its first factory.
 
The outright failures have been mostly less prominent: algae breeding for biofuels and various carbon dioxide capture technologies, along with efforts to knit together hydrocarbons from sunshine, carbon dioxide and water. But some have proved more conspicuous. ARPA–E feted a would-be breakthrough battery maker named Envia in 2012. But by 2014, while at least one of the entrepreneurs backing the company still mingled in the summit’s halls at the Gaylord National Resort & Convention Center in Maryland, Envia was mired in lawsuits and failed to deliver the energy-dense batteries it promised to General Motors. "I don't call them failures, I call them opportunities to learn," argued ARPA–E’s first director, Arun Majumdar, in a 2012 interview with Scientific American about failed projects in general. "If 100 percent of these projects worked out, we're not doing our job."
 
ARPA–E is definitely doing its job then: Biofuels haven't quite delivered on their promise, even engineering tobacco plants for oil, while electrofuels were a "crazy-ass idea," to use a term employed by William Caesar, president of the recycling business at Waste Management, at the 2014 summit to describe some of the concepts his company has evaluated for investment. And ARPA–E's budget has always been too small to tackle innovation in certain areas. "My real hope was to have enough of a budget to try out something different than what we are doing in the nuclear field today," such as a prototype for a new kind of reactor, Majumdar said in a 2013 interview with Scientific American.
 
"If you're solving for climate change and you're a serious person, your strategy starts with nuclear," said David Crane, CEO of the electric utility NRG, at this year's summit. But ARPA–E's budget has always been too small to encompass, for example, the hundreds of millions of dollars Crane lost during his tenure in a failed bid to build new standard nuclear reactors in Texas.
 
An analysis of the biggest programs by year and funding shows that electrofuels drew the biggest investment (at more than $41 million) in fiscal year 2010 followed by better hardware and software for the U.S. grid to help integrate renewables in 2011. But in fiscal year 2012 the biggest tranche of funding to a single program went to Boysen's MOVE projects (roughly $30 million) and, in fiscal year 2013, just behind the $36 million invested in better batteries for electric cars, was the REMOTE program of projects garnering $34 million. "It could have a small environmental footprint," argues Ramon Gonzalez, program director for Reducing Emissions using Methanotrophic Organisms for Transportation Energy (REMOTE). "We can develop something that is a bridge to renewable energy or even is renewable itself in the future."
 
Natural gas hardly seems to need ARPA–E's help to become ubiquitous. And although natural gas can help with climate change in the short term—displacing coal that emits even more pollution when burned to generate electricity—in the long run it, too, is a fossil fuel and a greenhouse gas itself. Burning methane for electricity will also one day require capturing and storing the resulting carbon dioxide in order to combat climate change. ARPA–E has not succeeded in delivering a technological breakthrough that would allow that to happen cheaply or efficiently, despite investing more than $30 million in its Innovative Materials and Processes for Advanced Carbon Capture Technologies (IMPACCT) back in 2010. "ARPA–E needs to revisit carbon capture and storage," said Michael Matuszewski of the National Energy Technology Laboratory at this year's summit.
 
Long game
Significant changes in energy sources—say from wood to coal or the current shift from coal to gas—take at least 50 years, judging by the record to date. "Looking at the climate risk mitigation agenda, we don't have 50 to 60 years," U.S. Secretary of Energy Ernest Moniz argued at the 2014 summit. "We have to cut [that time] in half," and that will require breakthrough technologies that are cheaper, cleaner and faster to scale.
 
It is also exactly in times of overreliance on one energy source that funding into alternatives is not only necessary, but required. ARPA–E should continue to focus on transformational energy technologies that can be clean and cheap, even if political pressures incline the still young and potentially vulnerable agency to look for a better gas tank. After all, if ARPA–E and others succeed in finding ways to use ever-more natural gas, new shale supplies touted to last for a century at present consumption rates could be exhausted much sooner. "Before this so-called 'shale gale' came upon us, groupthink had most of us focusing on energy scarcity," warned Alaska Sen. Lisa Murkowski (R) at the 2013 summit. "The consensus now is one of abundant energy. Don't fall into the trap of groupthink again."
 
Failure is a necessary part of research at the boundaries of plausibility.  As ARPA–E's Martin said at this year's summit: "It's part of the process." Many of the ideas the agency first funded were ideas that had sat unused on a shelf since the oil crisis of the 1970s. And the ideas that go back on the shelf now, like the artificial leaf, provide the basic concepts—designer, metal-based molecules—for new applications, like flow batteries.
 
The artificial leaf, for one, could benefit from ARPA–E or other research to bring down the cost of the photovoltaic cells that provide the electricity to allow the leaf's designer molecules to do their water-splitting work. Already, cheaper photovoltaics may be ushering in an energy transition of their own, cropping up on roofs across the country from California to New Jersey.
 
When such renewable sources of energy become a significant source of electricity, more storage will be needed for when the sun doesn't shine or the wind doesn't blow—and that storage needs to be cheap and abundant. In Germany, where the wind and sun now provide roughly one quarter of all that nation’s electricity, the long-term plan is to convert any excess to gas that can then be burned in times of deficit—so-called power to gas, which is a fledgling technology at best. And why couldn't clean hydrogen be that gas, as Nocera has suggested?
 
So the artificial leaf bides its time, while research continues at the Joint Center for Artificial Photosynthesis established with DoE money in California. Failure is an investment in future success. "The challenge is not that the technology doesn't work, but the economics don't work," observed Waste Management's Caesar at the 2014 ARPA–E Summit. "I don't like to talk about dead ends. There are things that their time just hasn't come yet."