'Conserve, conserve, conserve': A megawatt saved is better than a megawatt made

With the world鈥檚 energy needs growing rapidly, can zero-carbon energy options be scaled up enough to make a significant difference? How much of a dent can these alternatives make in the world鈥檚 total energy usage over the next half-century? As the MIT Energy Initiative approaches its fifth anniversary next month, this five-part series takes a broad view of the likely scalable energy candidates.

It鈥檚 often overlooked in discussions of how to meet the world鈥檚 growing appetite for energy, but many analysts say it鈥檚 the single biggest potential contributor to meeting the world鈥檚 energy needs: efficiency.

Doing more with less fuel or electricity could reduce humanity鈥檚 energy demands by as much as half. No technological breakthroughs are needed for such savings, just some well-designed regulations and policies.

Improving energy efficiency is not only a good idea, says Daniel Nocera, it is 鈥渁bsolutely essential, at an unprecedented scale.鈥� How big a scale? According to Nocera, MIT鈥檚 Henry Dreyfus Professor of Energy, what鈥檚 needed, as human energy consumption grows over the next few decades, is to save an amount of power equal to today鈥檚 total consumption 鈥� about 14 terawatts (trillions of watts).

But efficiency is something we already know how to achieve; we just need to figure out how to pay for it. 鈥淲e know exactly what to do, but it costs money,鈥� Nocera says. Present-day systems that use fossil fuels are all energy-efficiency laggards, he says: Everything from car engines to coal-burning powerplants to oil-fired home-heating systems are, on average, only about one-third efficient.

鈥淵ou need a proactive policy鈥� to require efficiency improvements and provide incentives for their implementation, he says. With such policies, 鈥測ou can go pretty fast down this road鈥� in improving things, he says.

But some people, especially those with a vested interest in a particular energy source, often downplay the feasibility and potential importance of other solutions, says John Sterman, the Jay W. Forrester Professor of Management and Engineering Systems at MIT鈥檚 Sloan School of Management. 鈥淥ne bias people have is toward more supply, and less toward efficiency,鈥� he says. 鈥淏ut efficiency is one of the biggest sources in the mix. In fact, it鈥檚 number one.鈥�

But even though the importance of efficiency is well-known, implementation faces many obstacles. For example, there鈥檚 the hurdle known as the landlord-tenant problem. In a nutshell, improvements in a building鈥檚 energy efficiency are typically paid for by the building鈥檚 owner, whereas the tenants 鈥� who often pay the utility bills 鈥� get the savings. Without regulations such as stronger building codes, financial incentives or gain-sharing mechanisms, a landlord has little motivation to make changes. With roughly a third of American homes 鈥� and many commercial buildings as well 鈥� occupied by renters, the landlord-tenant problem means tens of millions of properties are unlikely to undergo energy upgrades.

This kind of dichotomy is widespread, often in situations where it鈥檚 hardly recognized. For example, Sterman says, at an institution like MIT, when a researcher has to order a new piece of equipment for a lab 鈥� say, a freezer to store samples 鈥� the freezer鈥檚 cost comes out of the individual鈥檚 grant, but the operating cost of the electricity comes out of building鈥檚 overhead, so the incentives are inherently stacked against a more efficient, but also more expensive, purchase.

Partly because of such economic disincentives, 鈥渋n the United States, we use dramatically more energy per dollar of GDP, and per person, than in other countries,鈥� Sterman says, 鈥渁nd without any benefit to our quality of life.鈥�

鈥淚f you could have the same comfort level in your home with half the energy bill, you would clearly be better off,鈥� he adds. 鈥淎nd that鈥檚 technically possible.鈥� It just requires well-known measures such as insulating the walls, installing better windows and investing in appliances that are more efficient. 鈥淢any of these have pretty short payback periods, and often your home will be more comfortable than before, as well,鈥� Sterman says.

A missing ingredient that could drive greater efficiency is a set of standards that would make it easier for people to compare products and know what their energy savings could be. The U.S. government鈥檚 EnergyStar standards for appliances provide some of that kind of guidance. But, for example, although there has been a big recent push toward electric cars and plug-in hybrids, there are still no standards for charging stations or connectors, or ratings for different kinds of battery systems that would help people make comparisons. 鈥淣one of these have been worked out, and that slows the rate of diffusion鈥� of new technologies, Sterman says.

But some kinds of inefficiencies are not so easily reduced. For example, about two-thirds of the energy used to generate electricity using conventional steam turbines is wasted, regardless of whether the steam is heated by coal, oil, gas or nuclear fission. 鈥淵ou might think that鈥檚 terribly wasteful, but in fact it鈥檚 just the second law of thermodynamics,鈥� which limits the theoretical efficiency of any process to derive work from heat, says Robert Jaffe, the Otto (1939) and Jane Morningstar Professor of 麻豆淫院ics, who co-teaches a class on the physics of energy. 鈥淲e can鈥檛 expect to do much better鈥� in the design of such systems, he says.

Still, some of these systems are better than others: Currently, the most efficient heat-based generators are combined-cycle natural-gas plants, which use a two-stage system to squeeze the maximum energy out of the fuel, achieving overall efficiencies of around 60 percent. 鈥淐ogeneration of steam for heating, to run air conditioning or for industrial processing can make the overall efficiency even higher,鈥� Jaffe says.

That means simply making greater use of existing combined-cycle gas plants, and less use of older, much less efficient coal plants, could achieve a 20 percent reduction in overall U.S. greenhouse gas emissions without building a single new powerplant, according to a 2011 MIT study. (This takes into account the fact that not only are these plants more efficient, but natural gas also produces only about half the emissions that coal does.)

鈥淓veryone agrees [efficiency] is the low-hanging fruit,鈥� Jaffe says. In some forms, improved efficiency can be painless, he says 鈥� such as substituting fluorescent lights, or soon, the even-better LED lights, for conventional bulbs. Other efficiency improvements may entail some costs or adjustments, such as using cars that have somewhat less power for acceleration or that cost a bit more.

The implementation of efficiency improvements is full of questions and complexities, but the basic goal 鈥� and overwhelmingly, the single most important arena for making a major dent in greenhouse emissions 鈥� is crystal clear. As Jaffe puts it: 鈥淲hat can be done? Conserve, conserve, conserve.鈥�