Hot air balloon with solar collector and heat-engine-driven fuel cell

Patent metadata

Field	Value
Publication number	US-9290258-B1
Application number	US-201414310161-A
Country	US
Kind code	B1
Filing date	Jun 20, 2014
Priority date	Jun 20, 2014
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

An example balloon system for long-duration flight can include an optically transparent envelope for solar greenhouse heating of lift gas within, a fuel cell inside a bladder within the envelope, and a solar collector beneath the bladder configured to concentrate solar energy in a focal region below the bladder. The fuel cell can include hydrogen gas, oxygen gas, and a water reservoir in a bottom portion of the bladder, and could be configured to generate electricity to run a heater to heat the lift gas during night-time hours. The example system can also include a heat engine configured with a hot side in the focal region and a cold side in the water reservoir. The heat engine could be configured to generate power by transferring heat from the hot side to the cold side, and the power could be used to recharge the fuel cell during daylight hours.

First claim

What is claimed is:

1. A balloon system comprising:
an optically transparent envelope configured for solar greenhouse heating of lift gas within the optically transparent envelope;
a bladder inside the optically transparent envelope;
a fuel cell system inside the bladder, wherein the fuel cell system includes a supply of hydrogen gas, a supply of oxygen gas, and a water reservoir in a bottom portion of the bladder, and wherein the fuel cell system is configured to generate electricity;
a reflective solar collector beneath the bladder configured to concentrate solar energy in a focal region inside the optically transparent envelope and below the bladder; and
a heat engine configured with a hot side in the focal region of the reflective solar collector and a cold side in the water reservoir, wherein the heat engine is configured to generate power by transferring heat from the hot side to the cold side, and wherein a portion of the transferred heat is used for causing at least a portion of the water in the reservoir to vaporize.

2. The balloon system of claim 1 , wherein the reflective solar collector is configured to concentrate solar energy in the focal region by being oriented with respect to the sun to concentrate solar energy in the focal region by a concentration factor in a range of 10 to 1,000, and
wherein the hot side of the heat engine is configured to be heated to a temperature in a range of 100° C. to 1,000° C. by the concentrated solar energy in the focal region.

3. The balloon system of claim 1 , wherein the reflective solar collector is one of a reflective parabolic surface having a focal region between its surface and the bladder, or a reflective spherical-section surface having a focal region between its surface and the bladder,
and wherein the reflective solar collector is configured to concentrate solar energy in the focal region by being caused to track the sun during times of daylight when the sun is above the local horizon of the balloon system.

4. The balloon system of claim 1 , wherein the heat engine is one of an thermo-mechanical heat engine, a thermo-acoustic heat engine, or a photo-voltaic device.

5. The balloon system of claim 1 , wherein causing at least the portion of the water in the reservoir to vaporize comprises:
disposing of surplus heat transferred from the hot side to the cold side of the heat engine, the surplus heat being a portion of excess transferred heat beyond that which is used for generating power with the heat engine; and
transferring a portion of the disposed surplus heat from the bladder to the lift gas in the optically transparent envelope.

6. The balloon system of claim 1 , wherein the balloon system is further configured for using a portion of the electrical power generated with the fuel cell to operate one or more electrically-powered devices of the balloon system.

7. The balloon system of claim 1 , wherein the bladder is optically transparent,
wherein the reflective solar collector is configured inside an optically transparent containment vessel within the optically transparent envelope and below the bladder,
and wherein the focal region of the reflective solar collector is configured to be located within the optically transparent containment vessel.

8. The balloon system of claim 7 , wherein the optically transparent envelope is configured for maintaining a gas pressure within the optically transparent envelope equal to atmospheric pressure outside of the optically transparent envelope,
and wherein each of the bladder and the optically transparent containment vessel is configured for maintaining an internal gas pressure that is higher than the gas pressure within the optically transparent envelope.

9. The balloon system of claim 1 , wherein the lift gas is atmospheric air drawn into the optically transparent envelope through an opening at the bottom of the optically transparent envelope,
wherein the balloon system is configured to increase its buoyancy by heating the lift gas within the optically transparent envelope,
and wherein the balloon system is configured to decrease its buoyancy by controllable release of at least portion of the lift gas from the optically transparent envelope through an adjustable vent in the optically transparent envelope.

10. The balloon system of claim 9 , wherein the balloon system is further configured to create a balance between increased buoyancy from heating the lift gas and decreased buoyancy from controllable release of the lift gas, wherein the balance comprises a net buoyancy for causing the balloon system to float at a given altitude.

11. The balloon system of claim 9 , wherein the balloon system is configured for heating the lift gas within the optically transparent envelope by solar greenhouse heating of the lift gas during times of daylight when the sun is above the local horizon of the balloon system,
and wherein the balloon system is configured for heating the lift gas within the optically transparent envelope by powering a heater with the electrical power generated with the fuel cell during night-time when the sun is below the local horizon of the balloon system.

12. The balloon system of claim 9 , wherein the balloon system is further configured for using a portion of the power generated with the heat engine to recharge the fuel cell system.

13. The balloon system of claim 12 , wherein using the portion of the power generated with the heat engine to recharge the fuel cell system comprises:
generating electricity with the portion of the power generated with the heat engine; and
using the generated electricity to run the fuel cell in reverse.

14. The balloon system of claim 12 , wherein the fuel cell system includes a supply of hydrogen gas, a supply of oxygen gas, and the water reservoir in the bottom portion of the bladder, and wherein the fuel cell system is configured to generate electricity by:
converting a portion of the hydrogen gas and a portion of the oxygen gas into produced water by a chemical process that generates electricity and releases heat; and
storing the produced water in the reservoir.

15. The balloon system of claim 14 , wherein using the portion of the power generated with the heat engine to recharge the fuel cell system comprises:
converting a portion of the water in the reservoir into recovered hydrogen gas and recovered oxygen gas by a chemical process that dissociates H 2 O into hydrogen gas and oxygen gas; and
storing the recovered hydrogen gas with the supply of hydrogen gas, and storing the recovered oxygen gas with the supply of oxygen gas.

16. A method comprising:
generating electrical power with a fuel cell system inside a bladder within an optically transparent envelope of a balloon system, the optically transparent envelope being configured for solar greenhouse heating of lift gas within the optically transparent envelope, and the balloon system including a reflective solar collector beneath the bladder;
orienting the reflective solar collector to concentrate solar energy in a focal region below the bladder and containing a hot side of a heat engine, the heat engine being configured with a cold side in a water reservoir of the fuel cell system in a bottom portion of the bladder;
generating power with the heat engine by heat transfer from the hot side of the heat engine to the cold side of the heat engine; and
vaporizing at least a portion of the water in the water reservoir using at least a portion of the transferred heat.

17. The method of claim 16 , wherein orienting the reflective solar collector to concentrate so

Assignees

• Google Inc

Inventors

• Devaul Richard Wayne

Classifications

• B64B1/40 Primary

  Balloons (B64B1/58 takes precedence; toy balloons A63H27/10) · CPC title

• B64D2041/005

  Fuel cells · CPC title

• Y02T90/40

  Application of hydrogen technology to transportation, e.g. using fuel cells · CPC title

• B64B1/62

  Controlling gas pressure, heating, cooling, or discharging gas · CPC title