Renewable Facts

Question 1

How much did renewable energy grow in the last decade?

Answer 1

Renewable energy has doubled in a decade, while the amount of capacity coming from wind and solar has quintupled, from 57 million megawatt hours in 2008, to 301 million megawatt hours in 2018. (EIA)

Question 2

After all that, what portion of electricity comes from renewables?

Answer 2

About 17.6% comes from renewables, including hydro (6.9%), wind (6.5%), solar (2.3%) and biomass/geo (1.9%).

Question 3

How much more clean energy did nuclear plants provide?

Answer 3

Nuclear provided 19% of U.S. electricity in 2018. The remainder of 63.4% came from fossil fuels. (EIA)

Question 4

If we include all energy, not just electricity, what portion came from renewables?

Answer 4

About 11% (U.S. Energy Information Administration)

Question 5

What is the average wind turbine capacity in the US?

Answer 5

Average capacity was 2.0 megawatts (MW) in 2015.

Question 6

How much installed onshore wind power was there globally by the end of 2015?

Answer 6

There was 433 gigawatts (GW) of installed wind by the end of 2015, with 74 GW of that in the US (145 GW installed in China).

Question 7

What are state-of-the-art potential game-changing wind technologies and how much better might they be?

Answer 7

High altitude wind, which requires an airborne energy harvester, such as proposed by Makani and KiteGen. While concepts are still in development, initial energy return on energy investment is estimated at >300, much higher than other renewables.

Question 8

How much solar power is there in 2015?

Answer 8

Global solar photovoltaics (PV) was 227 GW in 2015 and includes PV and concentrating PV (CPV).

Question 9

What are current PV technologies?

Answer 9

PV technologies include: 1) Mono and polycrystalline silicon (c-Si); 2) Gallium arsenide (GaAs), which is more efficient and more expensive; 3) III-V Multijunction, which stack multiple material layers that absorb at different wavelengths and increase efficiency; and 4) Thin-film designs, including thin film cadmium telluride (CdTe), copper indium gallium selenide (CIGS) and hydrogenated amorphous silicon (a-Si:H), thinner layers, less efficient but higher power to mass ratios.

Question 10

How does Concentrated Solar Photovoltaics work?

Answer 10

It uses concentrated solar energy as a thermal source, driving a steam turbine. It must track the sun with great stability, utilizing either single-axis or two-axis concentration designs, to maintain high operating temperatures, and is more expensive.

Question 11

How much hydropower is there?

Answer 11

Worldwide hydropower capacity was 1,064 GW in 2015, generating 3,940 TWh/year, or ~19% of total energy demand, led by China, Canada, Brazil and the US.

Question 12

Is hydropower considered green energy?

Answer 12

California does not count hydropower facilities as renewable unless they are <30 MW. In addition to displacing people and habitats when constructing reservoirs, dams may promote anaerobic decay of organic matter, generating the potent GHG methane.

Question 13

What is tidal power and what are its prospects?

Answer 13

Marine and hydrokinetic (MHK) technologies are distinct from hydropower, exploiting energy from waves, tides, and river and ocean currents. MHK is still immature and hence expensive, and has recently suffered technological and commercial setbacks.

Question 14

What is geothermal?

Answer 14

Large-scale geothermal energy is produced in high-temperature regions at shallow depths (typically >1 km), using either natural or injected water to extract heat from rock. This heat originates from residual energy of Earth’s formation supplemented by natural radioactive decay. In contrast to small-scale geothermal heat pump systems utilized widely for homes and buildings, attractive locations for large-scale electricity production are very limited geographically, and most conventional potential in OECD countries has already been exploited. Conventional geothermal technologies require steam above 150°C for economic operation but lower temp applications exist, such as for building heating, water purification and mineral recovery.

Question 15

How much geothermal is there?

Answer 15

Global geothermal generation is projected to grow from 12 GW in 2013 to 32–63 GW in 2035.

Question 16

Are there game-changing geothermal technologies?

Answer 16

Enhanced Geothermal Systems (ESG) are reservoirs engineered to create energy from hot dry rock that otherwise lacks the water and/or permeability to be utilized. EGS has the potential to access geothermal resources at greater depth and could add >100 GW of capacity in the United States. A key enabling technology is hydraulic fracturing to increase permeability, similar to that used to produce unconventional natural gas. Strongly supported by the DOE, the technology is still at a research and development (R&D) stage, with goals to demonstrate a 5 MW system by 2020, and a cost-reduction pathway from ∼240 to ∼60 USD/MWh by 2030.

Question 17

How much biomass electricity generation is there?

Answer 17

Biomass electricity comprised ∼11% of total biomass energy utilization in 2013 (1), with the balance going to fuels production (mainly ethanol, biodiesel, and biogas) and traditional uses for cooking. Nonetheless, biomass electricity produces nearly zero net GHG emissions, and it is often an excellent way to use biomass when feedstocks are abundant and economical to procure. Total global biomass electricity generation was 108 GW in 2013 and is projected to grow to 230–355 GW in 2035.

Question 18

What is the potential of Biomass?

Answer 18

Biomass is a diffuse resource, limited by collection cost and constrained by competing uses of land and water. However, using biomass with CCS (BECCS) has high potential for achieving negative net GHG emissions in a cost-effective way, relative to other technologies.