Back to Energy’s Future? Jeffrey A. Mahn Nuclear Engineer (Retired) Albuquerque, NM USA jamahn47@gmail.com
Presentation Outline • • • • • •
Energy definition, forms, and facts A very brief history of energy Energy densities of resources used for electricity production Electricity-generation energy resource life cycle Accommodating electricity demand Electricity-generating facility performance – Electricity-generating efficiency – Facility capacity factor
• The problem with 100% “renewables”
Energy Defined • Energy – the ability to perform work (can be expressed in variety of units) • Conservation of energy – energy cannot be created or destroyed, only converted from one form to another • No work of any kind can be performed without expenditure of energy
Energy Forms
Energy Facts • Not all forms of energy can be converted completely into work, even under ideal conditions • Few energy conversion processes are 100% efficient • Available energy – portion of energy that can theoretically be converted into work • Useful energy – portion of energy actually converted into work • Energy conversion efficiency – ratio of useful energy to available energy
A Very Brief History of Energy Era Energy Resource Energy Density (kWh per kg)
Pre-Industrial Revolution Wind, Sun, Water, Animals, Humans < 0.001*
Industrial Revolution
Post-Industrial Revolution
Fossil Fuels
Uranium, Thorium
< 15
> 20 million
Resource Benefits
Familiar
24/7 electricity generation; major industrial development; vastly improved world economies; increased lifespan
Most reliable 24/7 electricity generation; essentially inexhaustible energy resource; safe, compact
Resource Shortcomings
Intermittent availability; very localized domains of use
Environmentally damaging waste; finite resources
Moderate waste impact on environment; public fear due to misinformation, poor education
* One hour’s work from 800 kg draft horse is about 0.0009 kWh/kg
Electricity Production • Common use of energy resources is electricity production • Only solar resource produces electricity directly • Other energy resources produce electricity indirectly by being converted into one or more other energy forms
Fossil Fuels (Chemical Energy) • Fuels formed over millions of years by natural processes such as decomposition of buried dead organisms • Examples – coal, oil, natural gas • Type of energy – chemical • Reaction of fossil fuels (hydrocarbons) with oxygen converts chemical energy to thermal energy • Generally used as heat source in steam cycle power plant to produce electricity
Chemical Reaction
Rearrangement of the atoms in this chemical reaction liberates about 50 kJ of energy per gram of CH4
Basic Steam Cycle
Nuclear Energy • Energy contained in nucleus of the atom • Heavy atom, such as uranium, can undergo nuclear reaction with free neutron causing it to split (fission) • Type of energy – nuclear • Uranium fission converts nuclear energy to thermal energy in nuclear reactor fuel elements • Generally used as heat source in steam cycle power plant to produce electricity
Fission of U-235 Nucleus
Splitting of the U-235 nucleus liberates about 200 MeV of energy (about 80 million kJ per gram of U-235)
Solar Energy • Transmitted to earth from sun in packets of energy called photons • Type of energy – radiant • Radiant energy (photons) incident on photovoltaic panel converted directly to electricity or to thermal energy (waste heat) depending on photon energy
Photon Absorption in Solar Cell
Wind Energy • Wind striking blades of wind turbine causes blades to move, causing wind turbine shaft to rotate • Type of energy – moving air mass has kinetic energy • Wind turbine converts wind (kinetic) energy to mechanical energy in rotating shaft, which drives a gearbox and electrical generator to produce electricity
Wind Energy Conversion
Water Energy • Water released from behind dam changes potential energy of water into kinetic energy • Type of energy – water elevated behind dam has potential (or gravitational) energy • Water turbine converts kinetic energy of water into mechanical energy in rotating shaft, which drives an electrical generator to produce electricity
Flowing Water Energy Conversion
No “Clean” Energy • Both positive and negative aspects to obtaining useful work from all energy resources • No energy resource is “free” or “clean” – Both direct and indirect costs associated with acquiring resources and manufacturing equipment and facilities to produce useful energy we consume in our daily lives – Entire life-cycle associated with using any energy resource to obtain useful energy results in byproducts and waste that can adversely affect the environment
Energy Resource Life-cycle
Electricity-Generating Facility Performance Two important performance parameters for electricitygenerating facilities • Efficiency ‒ Ratio of useful energy to available energy for any energy conversion device or system ‒ Can be calculated for electricity-generating systems using Energy Conversion Efficiencies chart (next slide)
• Capacity factor ‒ Ratio of actual electrical energy output over given period of time to maximum possible electrical energy output over that time period
Mechanical Mechanical Kinetic
Electrical Generator Efficiency Electricity generation efficiency will be investigated for the following power plants/facilities • • • • •
Coal-fired power plant Nuclear power plant Hydroelectric power plant Solar (Photovoltaic) power facility Wind turbine power facility
using energy conversion efficiencies from the previous slide.
Coal-fired Power Plant Efficiency (Conversion Device Minimum Efficiencies) Primary Energy Carrier Coal
Conversion Device
Conversion Device
Conversion Device
Boiler
Steam Turbine
Electrical Generator
Energy Conversion
Chemical to Thermal
Thermal to Mechanical
Mechanical to Electrical
Conversion Efficiency
0.85
0.40
0.95
System Efficiency
Electricity
Useful Output 0.32
Boiling Water Reactor Plant
Nuclear Power Plant Efficiency (Conversion Device Minimum Efficiencies) Primary Energy Carrier Uranium
Conversion Device Nuclear Reactor
Energy Conversion Conversion Efficiency
Nuclear to Thermal
0.90
Conversion Device
Conversion Device
Steam Turbine
Electrical Generator
Thermal to Mechanical
Mechanical to Electrical
0.40
0.95 System Efficiency
Electricity
Useful Output 0.34
Hydroelectric Power Plant
Hydroelectric Power Plant Efficiency (Conversion Device Minimum Efficiencies) Primary Energy Carrier Water
Conversion Device
Conversion Device
Conversion Device
Penstock
Water Turbine
Electrical Generator
Energy Conversion
Potential to Kinetic
Kinetic to Mechanical
Mechanical to Electrical
Conversion Efficiency
0.95*
0.86
0.95
* While there is minimal energy loss in a hydroelectric facility penstock, a minimum efficiency of 95% will be used.
System Efficiency
Electricity
Useful Output 0.77
Photovoltaic Facility
Inverter
Solar (Photovoltaic) Power Facility Efficiency (Conversion Device Minimum Efficiencies) Primary Energy Carrier Photon
Conversion Device
Conversion Device
PV Panel
Energy Conversion Conversion Efficiency
Inverter
Radiant to Electrical
DC Electrical to AC Electrical
0.20*
0.94* * See notes
Electricity
Useful Output System Efficiency
0.19
Wind Turbine
Wind Turbine Power Facility Efficiency (Conversion Device Maximum Efficiencies) Primary Energy Carrier Wind Conversion Device
Conversion Device Gearbox & Electrical Generator
Rotor Blades
Energy Conversion
Conversion Efficiency
Kinetic to Mechanical
Mechanical to Electrical
0.50*
Electricity
0.81* * See notes
Useful Output System Efficiency
0.40
Electrical Generator Efficiency Summary Summary of calculated electrical generator efficiencies: • • • • •
Coal-fired power plant – 32% Nuclear power plant – 34% Hydroelectric plant – 77% Photovoltaic facility – 19% Wind turbine facility – 40%
Efficiency for specific plant/facility may vary somewhat from these numbers depending upon age of energy conversion equipment and how well equipment is maintained
Electrical Generator Capacity Factor Conditions affecting plant/facility actual electrical energy output : • • • • •
Equipment failures Routine maintenance Electricity demand (e.g., load following units) Fuel availability (e.g., sunshine and wind) Environmental regulation (e.g., coal-fired units)
Typical energy system capacity factors shown on next slide
Energy System Capacity Factors Average Capacity Factor
Equivalent Full Power Days Per Year
Nuclear
92%
336
Geothermal
74%
270
Natural Gas
56%
204
Hydroelectric
41%
150
Coal
40%
146
Wind Turbines
35%
128
Photovoltaic
25%
91
Energy System
Source: Energy Information Administration, 2020
The Problem with 100% “Renewables”
Not All Energy Resources are Equal • Two types of demand, or loads, on electrical grid must be accommodated to meet residential and commercial needs – Base load electricity – minimum level of electricity demand required over period of 24 hours – Peak load electricity – maximum level of electricity demand exceeding base load level required over sustained period of time
• Solar and wind energy not suitable for generating base load electricity
Typical National Grid Daily Demand Profile
Typical California Daily Demand Load Profile
Source: California Load Profile for hot day in 1999, Lawrence Berkeley National Laboratory
PV Panel Efficiency vs Time of Day
“Renewables” Power Reality • We can only derive usable energy from “renewable” resources by using materials that aren’t renewable.1 – Old solar and wind electricity-generating equipment must be decommissioned, generating millions of tons of waste, much of it toxic. – Electric car batteries weighing about 1,000 pounds require mining, moving, and processing more than 500,000 pounds of raw materials somewhere on the planet. – Following a 7-year life, electric car batteries must be disposed of, with major toxic waste implications.
“Renewables” Power Reality (cont.) Eliminating fossil fuels and nuclear power would require a massive worldwide increase in mining for lithium, cobalt, copper, iron, aluminum, and numerous other raw materials. Producing wind turbines, solar arrays, and energy storage batteries requires mining, moving, and refining vast amounts of earth – far more than required to obtain the same amount of energy from coal, oil, and natural gas.1
“Renewables” Power Reality (cont.) • Building wind turbines and solar panels to generate electricity as well as batteries to fuel electric vehicles requires, on average, more than 10 times the quantity of materials compared with building machines for hydrocarbons to deliver the same amount of energy.1 • Hydrocarbons are needed to produce the concrete, steel, plastics, and purified minerals used to build “green” machines.
Minerals Used in Energy Technologies
“Renewables” Power Reality (cont.) Most equipment needed to mine and transport “green” energy materials must run on diesel fuel made from oil (they’re too big and heavy to be powered efficiently by batteries). Missing from the renewable energy discussion is the $0.5 trillion (or more) cost associated with 500,000 miles (or more) of new transmission lines required to connect the 50,000-plus wind and solar facilities for an all-renewables grid.1
The Battery Problem • Backup battery storage requirements for electricity demands of the entire U.S. would be absolutely staggering. Issues not being addressed include – How many batteries would be required to provide adequate backup electricity to the “green” grid when parts of the U.S. experience extended wind and sun “downtimes”? – Do sufficient raw materials even exist? – How would we dispose of huge amounts of toxic waste from battery manufacturing?
The Battery Problem (cont.) The battery problem not talked about Charging backup batteries requires off-grid wind and solar energy; i.e., energy not needed to satisfy immediate electricity demands.
Wind and solar facilities far in excess of that required to meet peak load demands would be necessary to charge all batteries that would be needed to provide electricity when wind and sun are not available.
The Battery Problem (cont.) Efficiency of storing and recovering wind and solar energy is 60%-70% for lead-acid storage batteries and 87%94% for lithium-ion batteries,1 which also adds to off-grid wind and solar facility requirements
Lithium batteries contain both oxidizers and fuel within the enclosed battery space, and therefore carry risk of fire and explosion in case of overcharging, over-discharging, excess current, or short circuits
Battery Storage Reality • The New York state Climate Leadership and Community Protection Act (CLCPA) requires 3,000 MW of battery storage to be built by 2030, at a cost of around $9 billion, which will provide about 10,000 MWh of electricity over four hours. • In 2019, average daily electricity consumption in the state was around 384,000 megawatt-hours (MWh).1 • So, on a typical NY winter day when the sun doesn’t shine and the wind doesn’t blow all of that battery storage would provide a little more than a half-hour’s worth of average daily use at current electricity consumption levels.
Battery Storage Reality (cont.) • The Tesla Megapack, a container-sized 3 MWh battery energy storage system, costs more than $1.2 million or more than $400 per kWh.1 • Due to the economy of scale, an installation of 100 Megapacks brings the cost down to around $280 per kWh.1 • For comparison, the U.S. average cost of electricity for the month of May 2021 was 13.71 cents per kWh for residential customers and 10.65 cents per kWh for all sectors of the economy.2
Battery Storage Reality (cont.) At the scale necessary to supplement on-demand “renewable” generated electricity, the cost of backup battery storage systems makes anything even close to 100% renewables economically impossible.1
The “Renewable” Energy Supply Chain Problem Share of top three producing countries in total production for selected minerals, 2019
The “Renewable” Energy Supply Chain Problem (cont.)
The “Renewable” Energy Supply Chain Problem (cont.) • Five of the world’s top-10 wind turbine manufacturers are Chinese-owned or operated. • Nine of the world’s top-10 solar panel manufacturers are Chinese-owned or operated. • China is responsible for 37% of passenger electric vehicles and 99% of e-buses sold globally since 2011.
The Bottom Line for “Renewable” Energy If all of America’s electricity is to be generated only by “renewable” energy resources, • America will always be dependent on foreign governments for the materials necessary for electricity production, and • electricity will necessarily be rationed; that is, brownouts and blackouts will be inevitable.
If all cars are to be electric vehicles only, there will not be enough electricity to keep them all charged.