Intergovernmental Panel on climate Change Working Group 3 (Mitigation) has produced their update from 2007. This post looks at electricity technologies.
Summary, also comments
• Improving efficiency much more rapidly in all sectors (energy production, distribution, and use) is crucial.
• Carbon capture and storage (CCS) is the single biggest addition to business as usual, if our goal is to keep atmospheric levels of CO2-equivalent below 450 ppm, or even 550. Plans for research and development, and deployment, should proceed rapidly and aggressively. (This will be aided by adding a cost to greenhouse gas emissions to cover their cost to society.)
• Bioenergy is the next most important technology. The “limited bioenergy” scenario increases bioenergy use to 5.5 times 2008 levels by 2050, and it will be very costly if we restrict bioenergy to that level. There are a number of concerns about how sustainable this path will be, and with larger increases in temperatures, the quantity of biomass available for electricity and fuels.
• If we don’t get our act together a few years ago, we will be using bioenergy and carbon capture and storage together. Bioenergy will take carbon dioxide out of the atmosphere and CCS will put it into permanent storage. This will cost several hundred dollars/ton CO2, and is relatively cheap compared to the alternative (climate change), although much more expensive than getting our act together.
• To the extent that we add nuclear, wind, and solar as rapidly as makes sense, we reduce dependence on bioenergy.
• Given the relative importance of carbon capture and storage, it may make sense for nations (e.g., Germany) and states (e.g., California) that want to jump start technologies to focus more on CCS than on renewables.
• Do all solutions, now.
Which solutions for electricity are important?
IPCC provides an answer by calculating the cost of failing to use the solution.
Efficiency remains the single largest technology solution, along with shifting to best available technologies: more efficient power plants, cars, buildings, air conditioners, and light bulbs. Since so many buildings are being constructed, and power plants built, with a lifetime of decades, early implementation of efficiency makes the task possible. The cost of failing to add efficiency sufficiently rapidly isn’t calculated in the Summary for Policymakers, but assume it’s more than we want to pay.
Nuclear and Solar + Wind
Can we do without renewables or nuclear power? Looking at only the attempt to reduce greenhouse gas emissions from electricity, IPCC found that opting out of nuclear power would increase costs by 7% in the 450 parts per million CO2-equivalent goal, and limiting wind and solar would increase costs by 6%. To stay below 550 ppm CO2-eq, costs would go up 13% (of a much smaller cost) without nuclear, and 8% without solar and wind. Crossing either off the list looks pretty unattractive.
Go to Working Group 3 for the full report, and the technical summary. IPCC also has an older report, Special Report on Renewable Energy Sources and Climate Change Mitigation.
Caveats re nuclear:
Nuclear energy is a mature low-GHG emission source of baseload power, but its share of global electricity generation has been declining (since 1993). Nuclear energy could make an increasing contribution to low-carbon energy supply, but a variety of barriers and risks exist (robust evidence, high agreement). Those include: operational risks, and the associated concerns, uranium mining risks, financial and regulatory risks, unresolved waste management issues, nuclear weapon proliferation concerns, and adverse public opinion (robust evidence, high agreement). New fuel cycles and reactor technologies addressing some of these issues are being investigated and progress in research and development has been made concerning safety and waste disposal.
I’m not sure what risks are associated with uranium mining.
Caveats re renewable energy (RE), excluding bioenergy:
Regarding electricity generation alone, RE accounted for just over half of the new electricity generating capacity added globally in 2012, led by growth in wind, hydro and solar power. However, many RE technologies still need direct and/or indirect support, if their market shares are to be significantly increased; RE technology policies have been successful in driving recent growth of RE. Challenges for integrating RE into energy systems and the associated costs vary by RE technology, regional circumstances, and the characteristics of the existing background energy system (medium evidence, medium agreement).
Note: the capacity factor for intermittents like wind and solar (and sometimes hydro), the percentage of electricity actually produced compared to what would be produced if the source ran at maximum capacity 24/7, is dramatically less than for nuclear and other sources of electricity. Added capacity (gigawatts brought online) does not communicate how much electricity, GWh, was added. The increase in coal in 2012 was 2.9% (see coal facts 2013). Since coal was 45% of 2011 electricity, the increase in coal was far greater than the increase in wind and solar combined.
The use of bioenergy increases dramatically in all scenarios. If we limit bioenenergy to 5.5 x 2008 levels, costs rise 64% (18% of a smaller number for 550 ppm scenario). Bioenergy, using plants for fuels and power (electricity) dominates high renewables scenarios.
Caveats re bioenergy:
Bioenergy can play a critical role for mitigation, but there are issues to consider, such as the sustainability of practices and the efficiency of bioenergy systems (robust evidence, medium agreement). Barriers to large scale deployment of bioenergy include concerns about GHG emissions from land, food security, water resources, biodiversity conservation and livelihoods. The scientific debate about the overall climate impact related to landuse competition effects of specific bioenergy pathways remains unresolved (robust evidence, high agreement). Bioenergy technologies are diverse and span a wide range of options and technology pathways.
There are many concerns about the amount of bioenergy—biopower and biofuels. With so many demands on land facing an increasing population wishing to supply food, fiber, green chemicals, etc in a world with a rapidly changing climate, sustainability is not foreordained. The Special Report on Renewable Energy Sources and Climate Change Mitigation estimates the net effect on yields to be small worldwide at 2°C, although regional changes are possible. By mid-century, temperature increase over pre-industrial could be more than 2°C, and yields are more uncertain.
Note: fusion energy is not mentioned in this short summary, but such strong dependence on bioenergy gives an idea why there is so much research on somewhat speculative sources of energy.
Carbon Capture and Storage
Carbon capture and storage (CCS) provides even more of the solution—costs go up 138% if we do without carbon capture and storage for the 450 ppm scenario (39% of a smaller number for 550 ppm scenario). Part of the attraction of CCS is that it can help deal with all the electricity currently made using fossil fuels. A number of countries are heavily invested in fossil fuel electricity, and a smaller number of countries, from China to Germany, are adding coal plants at a rapid rate, and will likely be reluctant to let expensive capital investments go unused. Additionally, as International Energy Agency (IEA) points out, almost half of carbon capture and storage is aimed at decarbonizing industry: steel, aluminum, oil refineries, cement, and paper mills use fossil fuel energy directly. Nuclear is often not practical in such situations, and wind and solar rarely are.
BECSS—Bioenergy and CCS
One of the cheaper ways to take carbon out of the atmosphere is to combine bioenergy and carbon capture and storage. Using plant matter to make electricity is nearly carbon neutral, as plants take carbon dioxide out of the atmosphere to grow, and release it back when they are burned for electricity or fuel. However, CCS can store that CO2 permanently. Cheaper is relative to the costs of climate change, as the cost is expected to be several hundred dollars/ton. This method is much more expensive than other methods of addressing climate change that are currently underutilized.
The International Energy Association booklet, Combining Bioenergy with CCS, discusses the challenges of ascertaining whether the biomass was grown sustainably.
Note: IEA gives some sense of how rapidly CCS should come online:
Goal 1: By 2020, the capture of CO2 is successfully demonstrated in at least 30 projects across many sectors, including coal- and gas-fired power generation, gas processing, bioethanol, hydrogen production for chemicals and refining, and DRI. This implies that all of the projects that are currently at an advanced stage of planning are realised and several additional projects are rapidly advanced, leading to over 50 MtCO2 safely and effectively stored per year.
Goal 2: By 2030, CCS is routinely used to reduce emissions in power generation and industry, having been successfully demonstrated in industrial applications including cement manufacture, iron and steel blast furnaces, pulp and paper production, second-generation biofuels and heaters and crackers at refining and chemical sites. This level of activity will lead to the storage of over 2 000 MtCO2/yr.
Goal 3: By 2050, CCS is routinely used to reduce emissions from all applicable processes in power generation and industrial applications at sites around the world, with over 7 000 MtCO2 annually stored in the process.
How much more low-GHG electricity is needed?
IPCC says 3 – 4 times today’s level by 2050. About 33% of today’s electricity is low-GHG, so by mid-century, more electricity than we make today will need to come from fossil fuel and bioenergy with CCS, nuclear, hydro, wind, solar, and other renewables.
For some of the challenges to rapidly increasing reliance on any energy source, see David McKay’s Sustainable Energy—Without the Hot Air.