Skip to main content


How to combat climate change? Measure emissions correctly

A new technology that measures moment-to-moment carbon emissions from electricity unlocks a host of opportunities.

Carbon emissions are arguably the most important thing for our society to learn how to manage in the coming years. The largest single source of U.S. carbon emissions is our electricity system. And yet, we do not measure emissions from our electricity use correctly, meaning we cannot manage our emissions effectively. 

But now, thanks to a new technology that accurately measures moment-to-moment carbon emissions on our electricity system, we can unlock a whole host of new opportunities to manage emissions creatively and with less effort. With new software that automatically tracks the actual emissions impacts associated with specific actions on the electricity system, both in real time and ahead of time, we can use our appliances at times when our electricity is the cleanest. 

End-use flexibility

Many uses of electricity have inherent flexibility — that is, the timing can be changed by small or large amounts without affecting the quality of the service that device is providing. As Rocky Mountain Institute explored in "The Economics of Demand Flexibility," harnessing this flexibility can save consumers and companies money while lowering grid costs.

The same is true of carbon emissions — harnessing the flexibility of end-use devices can make them run, on average, 15 percent cleaner than a "dumb" device, at no cost or quality impacts for the end-user. 

Millions of people and thousands of corporations try every day to manage their carbon emissions. Unfortunately, much of this effort occurs without measuring these emissions correctly. Personal and corporate efforts to manage carbon emissions from electricity typically happen in one of two ways: 

  • Without any measurement, by focusing on efforts that are generally associated with reduced emissions. For example, many corporations invest in things such as efficiency, solar PV and grid-sourced clean energy, but do not attempt to quantify the emissions savings associated with specific investments.
  • With coarse measurement of average emissions intensity, primarily by using eGrid historical data to estimate averages for electricity-related emissions. For example, a corporation deliberately might site a data center at a location on the grid that is, on average, cleaner than other options and claim some associated carbon emissions savings.

Thanks to new technology, it is possible instead to know the actual emissions impacts associated with specific actions at a specific place on the electricity system, in real time — and even ahead of time through predictive algorithms. More important, it is possible to assess future decisions based on marginal — rather than average — emissions factors, which, according to most economists, is the correct way to properly understand emissions impacts. 

Harnessing the flexibility of end-use devices can make them run, on average, 15 percent cleaner than a 'dumb' device, at no cost or quality impacts for the end-user.

The emissions hidden in the margins

The difference between average and marginal emissions factors can be very large, and quite important. An average factor refers to the amount of emissions generated over a given time, divided by the amount of energy produced in that time. For example, the U.S. Pacific Northwest gets most of its electricity from hydropower, a low-emissions energy resource, and thus its average emissions factor is very low.

A marginal emissions factor refers to rate at which emissions would change with a small change to electricity load. Continuing the simplified Pacific Northwest example, imagine a time when hydropower is providing 75 percent of the region’s power and gas-fired power plants are providing the remaining 25 percent.

This means that the average emissions factor of power in the Pacific Northwest would be very clean, at 25 percent the emissions intensity of natural gas (about 210 lbs. CO2 per megawatt-hour (MWh)). So at first glance, a great way to reduce a company’s or a person’s carbon footprint would be to move to the Pacific Northwest, where the electricity is very clean.

Yet in many cases, natural gas is the marginal resource, meaning that if a new kilowatt-hour of electricity is needed at a certain time, it will be provided by natural gas. So a company or an individual moving to the Pacific Northwest would increase carbon emissions at a rate equal to 100 percent of natural gas (840 lbs. CO2 per MWh) — a very big difference. Thinking in marginal rather than average carbon emissions dramatically can affect a company’s or a person’s choice of optimal environmental impact.

Estimating emissions impacts based on average emissions factors can have these types of effects on a recurring basis, across the U.S. This is because the portfolio of generators dispatching energy into the grid changes every five to 15 minutes, changing the marginal resource.

For example, Midwest utilities mostly burn coal at night; if you own an electric vehicle there, you would have lower CO2 emissions if you deliberately charged it during the day. On the other hand, California’s electricity market has more efficient gas plants on the margin at night than during the day, so you should charge your electric vehicle (EV) in the evening to minimize your CO2 emissions.

And with an Internet-connected EV charger, you can cut emissions even further with micro-timing. For example, you can time the EV charging to shut down when less-efficient peaking plants briefly kick on (say when the wind subsides or a cloud passes over), and turn it back on five minutes later when the wind returns or the cloud moves on and the marginal generator is cleaner. 

The difference between average and marginal emissions factors can be very large, and quite important.

Things you can do when you account for carbon emissions correctly

Accounting for carbon emissions correctly unlocks a whole host of new emissions-management opportunities. You can:

  • Change the timing of energy use: As noted above, this is likely the easiest and largest source of untapped savings since it doesn’t take any additional investments or impact end-use quality. It simply takes advantage of emerging controls technology associated with Internet-connected devices. Thermostats, EV chargers, commercial-scale HVAC units and demand-response programs, for example, can all run with lower emissions rates with just a few lines of computer code.
  • Change the location of both electricity use and generation: By locating energy generating (or consuming) facilities in a particular place, you can affect which power plants they take offline or use. Each MWh produced by a wind farm in West Virginia reduces twice as much carbon as a MWh from an identical farm in California. Yet today, a corporate buyer of renewable energy would view these two wind projects identically. To help buyers start to understand these effects, RMI’s Business Renewables Center has begun to track emissions intensity — the differences in emissions reduction from different renewables projects.
  • Value different energy conservation measures based on their actual carbon reduction potential: Today, all so-called negawatts, or avoided energy generation, are valued equally. But negawatts should have different values, as the Ohio and Texas examples show. A negawatt that displaces a kilowatt of coal power does more good to the planet than a negawatt that displaces a kilowatt of natural gas, wind or hydropower. Valuing on-site energy conservation measures and distributed generation based on actual emissions reduction potential can support better decision-making.
  • Price carbon markets correctly: If we do move to a world in which carbon emissions have a price, it would be great if it has the right price. Currently, renewable energy credits (RECs) and carbon offsets are priced, but only on average carbon impacts. Differentiating highly carbon-reducing RECs will lead to more cost-effective emissions reduction.

RMI and WattTime are working together to measure carbon emissions correctly and reduce them cost-effectively.

WattTime is a California-based nonprofit that has developed software to accurately forecast carbon emissions on the margin, in real time. This data can be used to control the timing of device charging, apply carbon emissions data to the models that renewable energy developers use to site projects, provide strategic advice to corporations on how to most cost-effectively reduce emissions, and provide more accurate reporting and verification of emissions.

RMI is using this new technological tool to unlock new markets for carbon reduction, and to maximize the value of these reductions. This technology can be used to improve the profitability of distributed energy resource companies and retail energy providers by lowering customer acquisition costs, accelerating corporate sustainability efforts and improving the way that carbon emissions are measured and, ultimately, priced. 

For example, 240 EV customers nationwide are charging their EVs with cleaner energy than their neighbors. Thousands of thermostat customers in Chicago are learning that cooling their houses with fewer carbon emissions is as easy as pushing a button. By using WattTime, millions of independent devices can be seamlessly checking the emissions content of the grid and making small decisions about the timing of electricity use to lower carbon emissions.

A key founding principle at RMI is that people don’t want raw kilowatt-hours. They want hot showers, cold beer and illumination. Similarly, the planet doesn’t care how many kilowatt-hours we reduce. It cares how much we reduce CO2 emissions. So why not start measuring them directly? Together, we will help people and companies easily reduce their carbon emissions to help create a world that’s thriving, verdant, and secure, for all, forever.

This story first appeared on:

Rocky Mountain Institute Outlet blog

More on this topic