Value chain · CLM-1410
In plain terms
US government studies around 1980 thought crops might be grown under a receiving station, because its mesh lets most sunlight through and warms the ground only slightly. They also said it would make farming and repairs harder, needed design changes and had not been studied properly. One later survey suggested raising the station and screening the ground from microwaves, or building greenhouses under it.
The claim as recorded
The US assessments of 1978-81 judged farming under a rectenna possible but unproven. DOE's 1980 statement of findings says "The rectenna design permits passage of about 80% of this sunlight, which may allow multiple use (e.g., agricultural) of the rectenna site." The 1978 exclusion-mapping study, citing a NASA informant, gives 80 per cent of sunlight passing and a heat rise beneath of "approximately one degree centigrade", concludes "multiple use cannot be said to be precluded", warns that it "will pose cultivation problems, repair and maintenance problems and will require design modifications", and itself assumes the land beneath "will be lost from functional, if not physical, standpoint". DOE's 1981 emerging-technology survey says a rectenna "constructed sufficiently far above the ground", with the area beneath "shielded from microwaves", would make it "feasible to use the land area for growing crops, grazing cattle, etc.", and proposes a "Greenhouse Rectenna".
Evidence behind this: DOE programme assessment findings, a DOE siting contractor's report and a DOE emerging-technology survey; statements of possibility, not trials.
Scope and limits
NO MEASUREMENT: no crop, animal or microwave exposure under a rectenna was measured in any of these sources. The 80 per cent and 1 degree C figures come from an informant, not a study. The microwave level beneath the panels is CLM-1008's, and the sources disagree (up to 5 against 0.01 to 0.23 mW/cm2). SRC-544's condition "shielded from microwaves" is a design requirement it does not specify. SRC-544 PDF 91 says "at least 80 percent transparent"; SRC-409 and SRC-512 say about 80.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF 16 [4], raw: "The rectertna design permits passage of about 80% of this sunlight, which may allow multiple use (e,g,, agricultural) of the rectenna site." (layer's "rectertna", "e,g,,"). SRC-512 PDF 11 [3], raw: "this siting study assumes that the land area directly beneath the receiving antenna will be lost from functional, if not physical, standpoint." PDF 49 [43] to PDF 52 [46], the sentence running across the figure pages; PDF 52 render read (the text layer scrambles its word order): "According to [a NASA informant], 80% of the incident sunlight should pass through the rectenna and the expected heat rise beneath the rectenna should be approximately one degree centigrade. From this information, multiple use cannot be said to be precluded. However, the use of land area beneath a rectenna will pose cultivation problems, repair and maintenance problems and will require design modifications." SRC-544 PDF 38 [29], normalised: "if the rectenna were constructed sufficiently far above the ground, and if the area beneath it were shielded from microwaves, it would be feasible to use the land area for growing crops, grazing cattle, etc." PDF 91 [82], raw: "The Greenhouse Rectenna." and "A study is needed to determine the impact on rectenna design (e.g., elevation of the structure to allow sufficient greenhouse space beneath)".
Basis: per cent of sunlight passing the rectenna; temperature rise beneath in degrees C; uses named (agriculture, greenhouse)
Related records
- Answers question
- QST-007 not published in this release
Cite this
energyaperture.com/c/clm-1410
CLM-1410, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-409
- CLM-0076The 1980 programme report says the three-year programme was due to end in 1980, that the heating experiments still needed data to confirm...CLM-1446The 1977-80 US government programme did not decide for or against power satellites. It said questions on technology, environment and cost...
- Also from SRC-512
- CLM-1105The first look, in 1978, used a coarser grid and a bigger site than the 1980 study, ruled out half to five-sixths of the country depending...
- Also from SRC-544
- CLM-1480A 1981 survey for the US energy department says that a beam steered by a signal from the ground cannot form without that signal. If the...